Patent Publication Number: US-7583414-B2

Title: Image input system

Description:
This application is a divisional of application Ser. No. 10/865,729, filed Jun. 10, 2004, now U.S. Pat. No. 7,321,453, which is a continuation of Ser. No. 08/603,611, filed Feb. 21, 1996 now U.S. Pat. No. 6,768,563, which priority under 35 U.S.C. §120 is claimed and which are hereby incorporated by reference herein in their entirety as if fully set forth herein. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a camera control system and, more particularly, to a camera control system in which at least one operator remotely operates at least one camera. 
   A video transmission system has been proposed in which large numbers of cameras and computers are arranged in a building and connected in a network to enable transmission of images or conversations using images and voices between two (or three or more) arbitrary points. For example, this system is expected to be used as a video conference system or a remote monitoring system. For these purposes, cameras whose direction and zooming can be externally controlled are already commercially available. In such a video transmission system each operator can remotely operate a given camera from a given place and/or display an image taken by a given camera on the screen of his or her computer. 
   In a video transmission system in which remote control of a given camera is possible, as the number of cameras to be operated increases it is more and more necessary to allow each operator to readily know the location of each camera. The present applicant has already proposed a system in which camera symbols indicating individual cameras are superposed on a map image which shows the installation sites of these cameras. The present applicant has also proposed a system in which the direction of each camera is indicated by the direction of a corresponding camera symbol. 
   The following problem arises when further improvements of a camera control system of this sort are attempted. That is, any user using the system can freely remotely operate cameras connected to other hosts and see images taken by these cameras. However, persons in the sensing enable ranges of the cameras to be remotely operated feel as if they were being monitored, and this may give them a strong unpleasant feeling. That is, under this condition the privacy of each person in the imaging range of a camera is invaded. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to solve the above conventional problem and provide a camera control system in which the protection of privacy is taken into consideration. 
   That is, it is an object of the present invention to provide a camera control system in which a range within which imaging is not permitted, i.e., an imaging inhibited range, can be set for each camera, and an image in this imaging inhibited range cannot be physically or essentially taken by a remote operation. 
   It is another object of the present invention to provide a camera control system in which each operator can easily recognize the imaging inhibited range of each camera which he or she intends to remotely operate. 
   It is still another object of the present invention to provide a camera control system which can rapidly set the imaging direction or the magnification of an image. 
   To achieve the above objects, a camera control system of the present invention has the following arrangements. 
   An image input system comprising: 
   image pick-up means for picking-up an image in a predetermined area; 
   setting means for setting an imaging inhibited area in which imaging is inhibited in the predetermined area; 
   input means for inputting an image of a desired area excluding the imaging inhibited area set by the setting means from the predetermined area picked-up by the pick-up means; and 
   display means for displaying the input image from the input means. 
   An image input system for displaying an input image, comprising: 
   at least one camera for picking-up an image of an object; 
   camera moving means for moving the camera by one or both of panning and tilting; 
   map display means for displaying a map showing a position of the camera and a direction in which the camera can be aimed by the camera moving means; 
   setting means for setting an imaging inhibited area in which image-picking-up is inhibited on the map displayed by the map display means; and 
   display means for displaying an image picked-up by a desired at least one of the at least one camera. 
   An image input system for displaying an input image, comprising: 
   at least one camera for picking-up an image of an object; 
   camera moving means for moving the camera within a predetermined range by one or both of panning and tilting; 
   direction designating means for designating a direction of a desired camera of the at least one camera; 
   message display means for displaying a message indicating that the camera cannot be moved, when the direction designated by the direction designating means falls outside the predetermined range; and 
   image display means for displaying an image picked-up by the desired camera. 
   An image input system for displaying an input image, comprising: 
   at least one camera for picking-up an image of an object; 
   camera moving means for moving the camera within a predetermined range by one or both of panning and tilting; 
   direction designating means for designating a direction of a desired camera of the at least one camera; 
   control means for aiming the camera at a position closest to the direction designated by the direction designating means, when the direction designated by the direction designating means falls outside the predetermined range; and 
   image display means for displaying an image picked-up by the desired camera. 
   An image input system for displaying an input image, comprising: 
   at least one camera for picking-up an image of an object; 
   region designating means for designating a partial region having a desired size and a desired position from an input image picked up by a desired camera of the at least one camera; and 
   display means for displaying the partial region designated by the region designating means. 
   An image display method of displaying an image picked-up by image pick-up means, comprising: 
   a setting step of setting an imaging inhibited area in which imaging is inhibited in a predetermined area; 
   an input step of inputting an image of a desired area excluding the imaging inhibited area set by the setting step from the predetermined area picked-up by the pick-up means; and 
   a display step of displaying the input image from the input step. 
   An image display method of displaying an image picked-up by at least one camera moved by one or both of panning and tilting by camera moving means, comprising: 
   a map display step of displaying a map showing a position of the camera and a direction in which the camera can be aimed by the camera moving means; 
   a setting step of setting an imaging inhibited area in which image picking-up is inhibited on the map displayed by the map display step; and 
   a display step of displaying an image picked-up by a desired one of the at least one camera. 
   An image display method of displaying an image picked-up by at least one camera moved within a predetermined range by one or both of panning and tilting by camera moving means, comprising: 
   a direction designating step of designating a direction of a desired camera of the at least one camera; 
   a message display step of displaying a message indicating that the camera cannot be moved, when the direction designated by the direction designating step falls outside the predetermined range; and 
   an image display step of displaying an image picked-up by the desired camera. 
   An image display method of displaying an image picked-up by at least one camera moved within a predetermined range by one or both of panning and tilting by camera moving means, comprising: 
   a direction designating step of designating a direction of a desired camera of the at least one camera; 
   a control step of aiming the camera at a position closest to the direction designated by the direction designating step, when the direction designated by the direction designating step falls outside the predetermined range; and 
   an image display step of displaying an image taken by the desired camera. 
   An image display method of displaying an image picked-up by at least one camera, comprising: 
   the region designating step of designating a partial region having a desired size and a desired position from an input image taken by a desired camera of the at least one camera; and 
   the display step of displaying the partial region designated by the region designating step. 
   A computer readable memory storing a program of displaying an image taken by image pick-up means, comprising: 
   codes of a process of setting an imaging inhibited area in which imaging is inhibited in a predetermined area; 
   codes of a process of inputting an image of a desired area excluding the imaging inhibited area set by the setting step from the predetermined area; and 
   codes of the display step of displaying the input image from the input step. 
   A computer readable memory of the present invention has the following arrangements. 
   A computer readable memory storing a program of displaying an image taken by at least one camera moved by one or both of panning and tilting by camera moving means, comprising: 
   codes of a process of displaying a map showing a position of the camera and a direction in which the camera can be aimed by the camera moving means; 
   codes of a process of setting an imaging inhibited area in which imaging is inhibited on the map displayed by the map display step; and 
   codes of a process of displaying an image taken by a desired one of the at least one camera. 
   A computer readable memory storing a program of displaying an image taken by at least one camera moved within a predetermined range by one or both of panning and tilting by camera moving means, comprising: 
   codes of a process of designating a direction of a desired camera of the at least one camera; 
   codes of a process of displaying a message indicating that the camera cannot be moved, when the direction designated by the direction designating step falls outside the predetermined range; and 
   codes of a process of displaying an image taken by the desired camera. 
   A computer readable memory storing a program of displaying an image taken by at least one camera moved within a predetermined range by one or both of panning and tilting by camera moving means, comprising: 
   codes of a process of designating a direction of a desired camera of the at least one camera; 
   codes of a process of aiming the camera at a position closest to the direction designated by the direction designating step, when the direction designated by the direction designating step falls outside the predetermined range; and 
   codes of a process of displaying an image taken by the desired camera. 
   The camera control system and method of the present invention with the above arrangements can designate an imaging inhibited area and thereby protect the privacy of a user. Additionally, since the imaging inhibited area can be set in a map window, the operation is easy and the imaging inhibited area can be clearly designated. 
   Also, even if a direction in which a camera is to be aimed is outside the movable range of the camera, the movement of the camera is restricted within the camera movable range. This prevents a damage to the camera. 
   Furthermore, an operator can set an imaging inhibited area and designate the direction of a camera while monitoring the view angle of the camera. This facilitates the operation. 
   The directions or the magnifications of a camera can be instantaneously switched. 
   Images such as are obtainable when a plurality of cameras are used can be obtained by using a single camera physically. 
   Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is a schematic block diagram showing the basic configuration of a computer system according to one embodiment of the present invention; 
       FIG. 2  is a schematic block diagram showing the hardware configuration of the embodiment in a network; 
       FIG. 3  is a schematic block diagram showing the software configuration of the embodiment in a network; 
       FIG. 4  is a view showing an example of a camera display control panel displayed on a display  35  by a camera control client  56 ; 
       FIG. 5  is a view for explaining setting of an imaging inhibited area; 
       FIG. 6A  is a flow chart showing processing of setting an imaging inhibited area; 
       FIG. 6B  is a flow chart showing the basic operation of a camera management server  50  with respect to the setting of an imaging inhibited area; 
       FIG. 7  is a detailed flow chart of step S 2  in  FIG. 6B ; 
       FIG. 8  is a schematic view showing the correspondence between an imaging inhibited area and an imaging inhibited direction; 
       FIG. 9  is a view showing an example of a camera status table; 
       FIGS. 10A and 10B  are schematic views showing the relationship between the pan enable direction and the imaging inhibited direction in case 1; 
       FIG. 11  is a schematic view showing the relationship between the pan enable direction and the imaging inhibited direction in case 2; 
       FIG. 12  is a schematic view showing the relationship between the pan enable direction and the imaging inhibited direction in case 3; 
       FIG. 13  is a schematic view showing the relationship between the pan enable direction and the imaging inhibited direction in case 4; 
       FIG. 14  is a schematic view showing the relationship between the pan enable direction and the imaging inhibited direction in case 5; 
       FIG. 15  is a detailed flow chart of step S 15  in  FIG. 7 ; 
       FIG. 16  is a view showing an example of a permitted host information file; 
       FIG. 17  is a view for explaining another method of setting an imaging inhibited area; 
       FIG. 18  is a view showing an example of a file for connecting set imaging inhibited areas and objective cameras; 
       FIG. 19  is a block diagram showing a common configuration applied to the second to fourth embodiments of a video camera controller according to the present invention; 
       FIG. 20  is a view showing a common graphic user interface applied to the second to fourth embodiments; 
       FIG. 21  is a view showing a common video camera control screen applied to the second to fourth embodiments and particularly explaining the second embodiment; 
       FIG. 22  is a view showing an example of determination of the camera movable range; 
       FIG. 23  is a flow chart showing the operation of the second embodiment; 
       FIGS. 24A and 24B  are views showing an outline of the operation of the third embodiment; 
       FIG. 25  is a view for explaining the operation of the third embodiment; 
       FIG. 26  is a flow chart for explaining the operation of the third embodiment; 
       FIG. 27  is a view showing an outline of the operation of the fourth embodiment; 
       FIG. 28  is a view for explaining the operation of the fourth embodiment; 
       FIG. 29  is a flow chart for explaining the operation of the fourth embodiment; 
       FIG. 30  is a block diagram showing an outline of the configuration of the fifth embodiment of the present invention; 
       FIG. 31  is a view showing an example of the screen in the fifth embodiment; 
       FIG. 32  is a view for explaining an input image and an extraction range; 
       FIG. 33  is a flow chart of the fifth embodiment; 
       FIG. 34  is a view showing an example of the screen when four extraction ranges are set; 
       FIG. 35  is a view for explaining four extraction ranges set in an input image; 
       FIG. 36  is a view showing a correspondence table of the extraction ranges and camera windows; 
       FIG. 37  is a flow chart for explaining an operation when N virtual cameras are included in a system; and 
       FIG. 38  is a view showing an example of a user interface for operating and displaying the extraction ranges. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present invention will be described below with reference to the accompanying drawings. 
   First Embodiment 
     FIG. 1  is a block diagram showing an outline of the configuration of a computer system in which a plurality of video communication terminals, i.e., cameras, which are basic elements in this embodiment of the present invention, are connected. One or more computers having the configuration shown in  FIG. 1  and/or one or more computers having a similar configuration are interconnected with each other via a computer network. 
   In  FIG. 1 , camera control circuits  12  ( 12 - 1 ,  12 - 2 ,  12 - 3 , . . . ) directly control, e.g., panning, tilting, zooming, focus adjustment, and aperture of video cameras  10  ( 10 - 1 ,  10 - 2 ,  10 - 3 , . . . ) in accordance with external control signals. A camera input selector  14  selects a video camera  10  to be controlled and inputs an output signal from the camera. RS-232C is an example of a control signal line. However, the present invention is obviously not limited to this interface. Note that although an output signal is usually a video signal, a video signal and an audio signal are output if a camera with a microphone is used. In the following description it is assumed that only a video signal is output. 
   A video communication terminal  20  sends a control command to a desired camera control circuit  12  via the camera input selector  14  and controls a video camera  10  connected to the camera control circuit  12 . Also, the video communication terminal  20  transmits an image picked-up by the selected camera to the network and receives images from the network. A CPU  22  controls the overall system by executing programs stored in a main storage  24  and a secondary storage (e.g., a hard disk drive)  26 . A mouse  28  is a pointing device. The mouse  28  and a keyboard  30  are used by an operator as input devices. 
   An I/O port  32  connects the camera input selector  14  and supplies camera control commands to the camera input selector  14 . A video board  34  inputs an output video signal from a video camera  10  selected by the camera input selector  14  and displays various images on a bit map display  35 . A network interface  36  connects the video communication terminal  20  to a computer network or a communication network. A system bus  38  interconnects the devices from the CPU  22  to the network interface  36 . Through the network interface  36  it is possible to send a camera control signal from a remote place to the video communication terminal  20  via the network and thereby control a given camera  10 . 
   The camera input selector  14  selects one of the control signal lines and one of the video outputs connected to the camera control circuits  12 . The camera input selector  14  supplies the selected video output to the video board  34  and logically connects the selected control signal line to the I/O port  32 . An NTSC signal which is a luminance/color-difference separation type signal is an example of the video signal format. The video board  34  inputs the video output selected by the camera input selector  14 . The input video signal is displayed as a dynamic image in a predetermined window of the bit map display  35  and/or transmitted to another terminal. 
   The secondary storage  26  stores various information, e.g., camera position information data and camera graphic data, pertaining to the cameras  10  and other cameras connected via the network. Details of these pieces of information will be described later. 
   If only one camera  10  is connected, the camera input selector  14  is unnecessary and one camera control circuit  12  is directly connected to the I/O port  32 . Also, if no video signals are transmitted, the cameras  10 , the camera control circuits  12 , and the camera input selector  14  are unnecessary. 
   The apparatus shown in  FIG. 1  is connected as a communication terminal to a network as illustrated in  FIG. 2 . Not all communication terminals need to have the configuration shown in  FIG. 1 . For example, the network can include a communication terminal to which only one camera is connected or a terminal to which no camera is connected (i.e., a terminal having a function of only remotely operating cameras connected to other terminals and displaying images from these cameras). Generally, communication terminals having such various configurations simultaneously exist in a single network. As the network used in this embodiment, a LAN or a WAN having an enough transmission band width to transmit digital dynamic image data and camera control signals is assumed. Dynamic image data is usually compressed before being transmitted. In this embodiment, however, a detailed description of the dynamic image compression method will be omitted since various existing methods are usable. 
   The video board  34  has the video capture function as described above. The video board  34  supplies input video data to the bit map display  35  to display images on it and also supplies the data to the CPU  22  through the bus  38 . The CPU  22  packetizes the video data and outputs the packet to the network via the network interface  36 . Packets of, e.g., a camera operation instruction and a camera switch instruction also are sent from the network interface  36  to the network. Additionally, packets of information pertaining to the overall system are sent to the network. These pieces of information are transmitted to either specified terminals or all terminals in accordance with the contents of data to be transmitted and with the necessity. 
   Reception is done in a similar fashion. That is, upon receiving packets of video data, a camera operation instruction, and a camera switch instruction, each video communication terminal  20  processes the received video data in the same manner as for internal capture data and processes the received camera operation and camera switch instructions in the same way as for analogous internal instructions. The information pertaining to the overall system is used to update system display of a user interface (to be described later). 
     FIG. 3  is a block diagram showing the software configuration in the system of this embodiment. Referring to  FIG. 3 , the video communication terminals  20  and a camera management server  50  are connected to a computer network  52 . A camera control server  54 , a camera control client  56 , and image transmitting/receiving software  58  are installed in each video communication terminal  20 . The camera control server  54  controls the camera  10  in accordance with a camera control signal (including a select signal if a plurality of cameras are connected) entered from the self-terminal or transmitted from another terminal. The camera control client  56  remotely operates the camera  10  of the self-terminal or another terminal. The image transmitting/receiving software  58  supplies an image from the camera  10  of the self-terminal to other terminals via the network  52  and supplies images transferred from other terminals via the network  52  and an image from the camera  10  of the self-terminal to the display  35  of the self-terminal. 
   The camera management server  50  is software for managing all cameras  10  available (or connected) to the network  52  and holds information such as the camera name, host name, installation position, and current status of each camera. The camera management server  50  also manages registration of a camera which is newly made usable via the network  52  and delete of a camera disconnected from the network  52 . Additionally, the camera management server  50  periodically informs all camera control clients  56  of the management information of all cameras. The camera management server  50  need only be stored in one of the terminals connected to the network  52 . 
   The camera control client  56  displays the locations and directions of the camera  10  of the self-terminal and all cameras usable via the network  52  on the screen of the display  35  of the self-terminal by superposing predetermined camera symbols on a map. The camera control client  56  also updates the display state of each camera symbol in real time on the basis of the camera information periodically sent from the camera management server  50 . 
   The camera control server  54 , the cameral control client  56 , the camera image transmitting/receiving software  58 , and the camera management server  50  are realized when the CPU  22  executes respective predetermined programs. 
     FIG. 4  shows an example of a camera display control panel displayed on the display  35  by the camera control client  56 . On a map showing the installation locations of operable cameras, a map window  60  superposes camera icons indicating the locations and directions of these cameras. A camera image window  62  displays an image from one selected camera. A camera operation panel  64  includes various camera control buttons and controls panning, tilting, and zooming of a selected camera. In this embodiment, it is assumed that a window display system capable of simultaneously displaying a plurality of windows is operating. 
   The map window  60  displays a map showing, e.g., the arrangement of seats in an office. On this map camera icons  66  indicative of the locations of individual cameras arranged in the office are superposed. Each camera icon  66  is displayed in the same position as the location of the corresponding camera and points in almost the same direction as the current camera direction. These camera icons  66  are displayed in different colors to distinguish between a camera which is currently selected to display an image or to be remotely operated, cameras used by other users, and cameras not used by anybody. 
   The operation panel  64  is displayed below the camera image window  62 . The operation panel  64  includes rotation operating buttons for panning and tilting and two buttons for a zoom operation. By operating these buttons, a user can operate rotation (panning and tilting) and zooming of a given designated camera. If an operation of a selected camera is impossible (e.g., if the camera is already being operated by some other user), the rotation operating buttons and the zoom operating buttons are displayed in an operation disable state. 
   For instance, when a certain user desires an access to (in this case a remote operation of) a certain camera, the user double-clicks the camera icon indicating the camera of interest. In accordance with this double-click, the camera control client  56  requests the camera management server  50  to issue the access right to that camera. If there is no user currently operating that camera, the camera management server  50  grants a permission to perform a remote operation (including display of an image) of the camera. If there is a user operating the camera, the camera management server  50  denies the access right. If the access right is granted, an output image from the camera is displayed in the camera image window  62  and operations (panning, tilting, and zooming) from the camera operation panel  64  are enabled. 
   Below the operation panel  64 , a set button  68  for setting an imaging inhibited area and a clear button  70  for canceling the set imaging inhibited area are displayed. In this embodiment, sensing a scene of an imaging inhibited area by the cameras is inhibited. The imaging inhibited area can be set in a camera control system which remotely operates a desired camera within an entire range in which the camera is operable. The imaging inhibited area is set for designated cameras or all cameras under the camera control system. A camera for which an imaging inhibited area is set cannot be remotely operated via the network to point in a direction in which the imaging inhibited area is sensed. 
   The processing of setting an imaging inhibited area in this embodiment will be described in detail below. 
   When a user clicks the imaging inhibited area set button  68 , the camera control client  56  draws vertical and horizontal lines partitioning the map window  60  into a mesh as illustrated in  FIG. 5 . Areas divided by these vertical and horizontal lines are set units of an imaging inhibited area. On the map window  60 , the user designates one or more divided areas in which he or she wants to inhibit sensing. The designated divided area (e.g., an area  92  in  FIG. 5 ) is enclosed by, e.g., red so as to stand out clearly from other divided areas. When a desired divided area is selected as an imaging inhibited area, the user double-clicks the mouse button on the selected divided area. Consequently, an imaging inhibited area is set. To cancel the imaging inhibited area, it is only necessary to click the clear button  70  by using the mouse. 
   When the imaging inhibited area is set or changed, this information is supplied to the camera management server  50 . The camera management server  50  changes the direction of a camera whose sensing range (field of view) includes the set or changed imaging inhibited area so that the imaging inhibited area is not sensed. Also, the direction of the corresponding camera icon  66  is similarly changed on the map window  60 . That is, the camera control client  56  operating in the communication terminal  20  in which the imaging inhibited area is set informs the camera management server  50  that the imaging inhibited area is set, and sends coordinate information of the set imaging inhibited area to the server  50 . 
     FIG. 6A  is a flow chart of the processing of the camera control client when an imaging inhibited area is set. This setting is done as described above. 
     FIG. 6B  is a basic flow chart of the camera management server  50  with respect to the setting and change of an imaging inhibited area. The camera management server  50  acquires coordinate information (coordinates of opposite corners of a rectangle) of the set imaging inhibited area (step S 1 ). The camera management server  50  searches for a camera whose current sensing range includes even a portion of the set imaging inhibited area. The camera management server  50  issues to the corresponding camera a camera control command for changing the direction of the camera to a direction in which the imaging inhibited area moves out of the sensing range, thereby changing the imaging direction of the camera (step S 2 ). Also, the camera management server  50  informs all camera control clients  56  of the changed direction of the camera whose direction is thus changed, and updates the direction of the corresponding camera icon  66  on the map window  60  (step S 3 ). 
     FIG. 7  shows a detailed flow chart of step S 2  in  FIG. 6B . First, a camera whose direction is to be changed and a camera whose rotatable angle is to be changed are selected (step S 11 ). Assume that cameras in a self-station locally connected to a host in which the imaging inhibited area is set are objective cameras. The camera management server selects these cameras by referring to host information of each camera. 
   The direction and the rotatable angle of each selected camera are changed. That is, of the cameras selected in step S 11 , a camera i of interest (whose zoom lens is set to the telephoto side) is selected in step S 12 . From the coordinates of the installation position of the camera i and the coordinates of the imaging inhibited area, an imaging inhibited angle θd (d&lt;θd&lt;D) in case that the optical system of the camera i is set to the widest angle is calculated as illustrated in  FIG. 8  (step S 13 ). Angles  d  and D are centered around the camera i at the two ends of the imaging inhibited area on the map plane. Camera control of the camera i is temporarily locked so that no user operates the camera i before the camera i is completely updated (step S 14 ). From a camera status table (to be described later) and the imaging inhibited angle calculated in step S 13 , the pan enable angle of the camera i is changed so that the camera i does not aim in the imaging inhibited direction. If the camera i is currently pointing in the imaging inhibited direction, a camera control command which changes the direction of the camera so that the camera moves out of the imaging inhibited angle is transmitted to a corresponding camera control server  54  (step S 15 ). Details of this change processing will be described later. When the necessary change processing is completed, camera control lock of the camera i is released (step S 16 ). 
   The processing from step S 13  to step S 15  is executed for all of the cameras selected in step S 11  by changing the camera of interest in steps S 17  and S 18 . 
     FIG. 9  shows an example of a camera status table  901  storing fixed information and current information of each individual camera. The table  901  consists of information such as camera numbers, camera names, host names, the coordinates of the camera installation positions on the map, initial directions upon start-up, pan enable angles θp. (a&lt;θp&lt;A), and current directions. The two ends of the pan enable angle are angles  a  and A, similar to  d  and D, represented by clockwise angles in a direction  x  (a predetermined direction on the map plane). 
   The camera management server  50  constantly checks the camera status table and so monitors that the individual cameras do not rotate beyond the respective pan enable angles. Also, the camera management server  50  periodically sends the contents of the camera status table to the camera control clients  56 . On the basis of the information from the camera management server  50 , each camera control client  56  updates the direction of each camera icon  66  in the map window  60  displayed on the display  35 . 
   The relationships between the pan enable angle θp (a&lt;θp&lt;A) and the imaging inhibited angle θd (d&lt;θd&lt;D) are classified into five cases described below. 
   In case 1, A&gt;a&gt;D&gt;d or a&lt;A&lt;d&lt;D as illustrated in  FIGS. 10A and 10B . In this case the pan enable angle and the imaging inhibited angle do not overlap at all. 
   In case 2, d&lt;a&lt;D&lt;A as shown in  FIG. 11 . In this case a portion of the imaging inhibited angle overlaps the pan enable angle. 
   In case 3, a&lt;d&lt;D&lt;A as shown in  FIG. 12 . In this case the imaging inhibited angle is entirely contained in the pan enable angle. 
   In case 4, a&lt;d&lt;A&lt;D as shown in  FIG. 13 . In this case a portion of the imaging inhibited angle overlaps the pan enable angle. 
   In case 5, d&lt;a&lt;A&lt;D as shown in  FIG. 14 . In this case the pan enable angle is entirely contained in the imaging inhibited angle. 
     FIG. 15  shows the details of step S 15  in  FIG. 7 . The camera status table  901  and the direction of the camera of interest are changed as follows in accordance with the five cases described above. Assume the current direction of the camera of interest is N. 
   First, in step S 21  which of the five cases is the current case is checked. 
   If case 1 is determined, this means that the imaging inhibited angle and the pan enable angle do not overlap each other. Accordingly, no change is made (step S 22 ). 
   If case 5 is determined, this means that the pan enable angle is entirely contained in the imaging inhibited angle. Therefore, control and display of the camera are turned off (step S 23 ). 
   If case 2 is determined, the current direction N of the camera is checked (step S 24 ). If a&lt;N&lt;D is determined (YES in step S 25 ), this means that the camera is currently aiming in the imaging inhibited area, and so the direction of the camera also needs to be changed. Accordingly, in the camera status table  901  the angle D outside the imaging inhibited angle is substituted into the information of the current camera direction N and into the end portion  a  of the pan enable angle (step S 26 ). Thereafter, a pan command for aiming the camera in the angle D is issued (step S 27 ). 
   Cases 3 and 4 are basically the same as case 2. In these cases, the pan enable angle is so changed as not to contain the imaging inhibited angle, and the direction of a camera pointing to the imaging inhibited angle is so changed that the camera does not aim at the imaging inhibited angle (steps S 28  to S 36 ). If a camera is pointing to the imaging inhibited angle in case 3, the camera is aimed at the angle D. However, it is also possible to point the camera to the angle  d  or to a larger end portion by comparing (A-D) with (d-a). 
   In the above embodiment, the imaging inhibited area is chosen from equally divided areas on the map. However, it is evident that a rectangle with a given size drawn on the map by dragging the mouse can also be set as an imaging inhibited area. In this case each user can set an imaging inhibited area with a given size. 
   In the above embodiment, after the imaging inhibited area is set, only cameras connected to the local host are chosen as a camera whose pan enable angle and direction of the cameras are to be changed. Accordingly, it is possible to impose limitations on the directions of the cameras in the self-station. Consequently, other users cannot remotely aim the cameras in the self-station in the direction of an area set as the imaging inhibited area. However, if only local cameras are the objects, the number of cameras whose camera operations can be restricted is limited. In situations where a large number of cameras exist, therefore, even if an imaging inhibited area is set it is sometimes possible to take an image of this imaging inhibited area from a camera of another host. Also, it is sometimes necessary to limit the operation of a certain camera from other hosts rather than a local host. 
   This objective or demand can be achieved by making an extension such that cameras connected to other hosts can also be set as a camera whose pan enable direction and imaging direction are changed in accordance with setting (or change) of an imaging inhibited area. This extension is made as follows. 
   Camera access permitted hosts are predetermined for each camera. As an example, a permitted host information file as shown in  FIG. 16  is formed. If an imaging inhibited area is set on the map of host  1 , for example, all cameras connected to all hosts to which a remote operation by host  1  is permitted are retrieved from the permitted host information file and set as objects to be changed. If all host names are set for a certain camera, it is of course possible to inhibit any camera from being aimed at the imaging inhibited area. If this is the case, the imaging inhibited area can never be imaged. 
   It is unnecessary to select an imaging inhibited area from equally divided areas on the map. For example, as illustrated in  FIG. 17 , it is possible to preset several areas with arbitrary sizes which may be set as an imaging inhibited area, store the position information of these areas, and, when an imaging inhibited area is to be set (changed), display these areas on the map so that any area can be selected. Accordingly, areas which can be set as an imaging inhibited area and areas which cannot can be distinguished in accordance with the user. As an example, a common place which is strongly public cannot be set as an imaging inhibited area when an imaging inhibited area is set (changed), if the place is not set as a candidate of an imaging inhibited area. 
   It is also possible to limit cameras (or hosts) whose operations are limited by an imaging inhibited area for each set imaging inhibited area. If this is the case, as illustrated in  FIG. 18 , a file connecting objective cameras to each set imaging inhibited area is formed. In  FIG. 18 , if area  1  is chosen as an imaging inhibited area, cameras  1 ,  2 ,  3 , and  5  are set as cameras whose pan is limited. This allows a rapid retrieval of cameras covering the imaging inhibited area. 
   In the above description, general users can freely set and cancel an imaging inhibited area. However, it is naturally also possible to permit only a specific manager to do these works. For example, a system manager or a direct manager of an objective camera (e.g., the user of a video communication terminal connected to the camera) can set an imaging inhibited area of each camera under the management and can change and cancel the setting. However, general users cannot set imaging inhibited areas of cameras which they do not manage and cannot change and cancel already set imaging inhibited areas. 
   As can be readily understood from the above explanation, in the present invention an imaging inhibited area which is inhibited from being imaged by a camera can be set on a map showing the arrangement of cameras. This makes it possible to protect the privacy of each user. Also, an operation for this purpose can be done by a readily understandable interface. 
   Second Embodiment 
   The second embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 
     FIG. 19  is a block diagram showing a video communication terminal of this embodiment. A display  100  as a display unit displays a video camera control window  10 ,  FIG. 20 . A video camera  101  incorporating a zoom lens can be panned and tilted by a panhead  109  which incorporates a motor (not shown). The motion of the video camera  101  is controlled by a video camera controller  102 . An image controller  103  encodes and decodes image signals. A communication controller  104  exchanges image information and video camera control information with a video camera controller installed in a remote place. A system controller  105  controls the overall system. An operation unit  106  as a designating means includes a keyboard, a mouse, and a digitizer and inputs designations to the system controller  105 . These controllers constitute a control means according to this embodiment. 
   The configuration in  FIG. 19  is equivalent to setting one video camera and omitting the camera input selector  14  in the configuration in  FIG. 1 . That is, the system controller  105 , the video camera controller  102 , the image controller  103 , and the communication controller  104  correspond to the video communication terminal  20 , the camera control circuit  12 , the video board  34 , and the network I/F  36 , respectively. Accordingly, a plurality of cameras can also be controlled by adding the camera input selector  14  to the configuration in  FIG. 19 . 
     FIG. 20  shows a graphical user interface (GUI) on a screen  100   a  of the display  100 . 
   A video camera control window  110  includes an image display screen  111 , a video camera control screen  112 , camera direction control buttons  113 ,  114 ,  115 , and  116 , and sensing range (field of view) control buttons  117  and  118 . The image display screen  111  displays an image currently being picked-up by the video camera  101 . The video camera control screen  112  is used to control the motion of the video camera  101 . The camera direction control buttons  113 ,  114 ,  115 , and  116  are used to change the camera direction upward, to the left, downward, and to the right, respectively, without using the video camera control screen  112 . The sensing range control buttons  117  and  118  are used to enlarge and reduce (zoom in and zoom out), respectively, an image of an object. The control window  110  also displays a cursor  119  for operating the control window  110 . This cursor  119  is operated by the operation unit  106  ( FIG. 1 ). The control window  110  further includes a button  107  for designating an imaging inhibited range and a clear button  108  for canceling the range designated by the button  107 . 
     FIG. 21  is an enlarged view of the video camera control screen  112 . Referring to  FIG. 21 , a sensing enable area  112   a  indicates a range which can be sensed by the video camera  101  when the zoom magnification is minimized (to the widest angle) and panning and tilting are performed over the entire range. The sensing enable area  112   a  has the same size as the video camera control screen  112 . A video camera movable area  112   b  indicates a range within which the optical axis of the video camera  101  can move. A sensing range display area  112   c  indicates a position and a range in the sensing enable area  112   a  which the video camera  101  is currently sensing. Although the size of the sensing enable area  112   a  is fixed, the sensing range display area  112   c  changes its size in accordance with the zoom magnification. 
   The video camera control screen  112  is displayed in place of the map display window  60  in the first embodiment. In the apparatus of this embodiment, it is assumed that one camera is connected to one video communication terminal. Accordingly, by displaying the sensing angle based on the visual field of the connected camera, the sensing enable range and the camera rotatable angle can be shown to the user. 
   Designation of an imaging inhibited range is done by the button  107 . The button  107  has the same function as the button  68  in the first embodiment. When the button  107  is depressed, the map window  60 ,  FIG. 5 , in which the arrangement of cameras and already divided areas are drawn is displayed, and an imaging inhibited area is designated on this map. In the same fashion as in the first embodiment, an angle at which cameras are inhibited from being aimed is calculated as shown in  FIG. 8  and registered as a camera status table  901 ,  FIG. 9 . Although the table in  FIG. 9  does not contain a camera tilt angle, in this embodiment it is assumed that the camera status table contains the tilt angle. 
   When the imaging inhibited area is thus designated, an angle at which a camera is rotatable is displayed on the camera control screen  112 , in place of the map window  60 , on the basis of the contents of the camera status table. In this case the camera movable area  112   a  is determined on the basis of a pan enable angle (a, A) registered in the camera status table  901 . Note that the pan enable angle and the tilt enable angle excluding the imaging inhibited angle will be collectively referred to as a camera movable range hereinafter. 
     FIG. 21  shows an example in which no imaging inhibited area is designated. If an imaging inhibited area is designated, as shown in  FIG. 22 , a permitted camera movable range is obtained by projecting the pan enable range of the camera onto a plane. This corresponds to the position and length in the horizontal direction of the camera movable area  112   b  and determines the positions of vertical lines  112   b - 1  and  112   b - 2  of the area  112   b.    
   An imaging inhibited area also can be designated on the camera control screen  112  in  FIG. 21 . That is, the camera movable area is directly designated by an operator by dragging the vertical line  112   b - 1  or  112   b - 2  and moving the line to a desired position by using the mouse. In this case the angles (A, a) at the two ends of the pan enable angle are calculated from the permitted camera movable area by a procedure which is the reverse of the procedure in  FIG. 22 . 
   A control procedure performed by the system controller  105  when an operator operates the camera on the camera control screen  112  thus obtained will be described below with reference to the flow chart in  FIG. 23 . 
   The user operates the video camera control screen  112 , the camera direction control buttons  113  to  116 , or the sensing range control buttons  117  and  118  in the video camera control window  110  by using the cursor  19 , thereby controlling the video camera  110  to take an image of a desired location (step S 230 ). 
   The coordinates of the selected camera direction are detected (step S 231 ). An area on the camera control screen in which the selected coordinates are present is checked (step S 232 ). 
   In this embodiment, if the user selects a position outside the video camera movable area on the video camera control screen  112  in  FIG. 21  by using the cursor  119  ( 119 - 1 ), an error is determined because the selected position is outside the video camera movable area, and nothing is done for the operation control of the video camera  101 . Preferably, to inform the user that the selection is an error, a message “position outside camera movable area is selected” is displayed on the video camera control screen  112  (step S 234 ). It is also possible, without displaying this message, to inform the user that the position cannot be selected, by replacing the cursor  119 - 1  indicating the position outside the video camera optical axis movable area with a symbol indicated by reference numeral  119 - 2 , which is a cursor with a mark “x” on it. 
   On the other hand, if the designated direction is within the camera movable area, the camera is aimed in that direction, and the camera status table is updated (steps S 233  and S 237 ). If the object camera to be operated is a remote-controlled camera, control information for rotating the camera is transmitted to a system control unit of the object camera (step S 236 ). 
   With the above control it is possible to prevent a damage to the panhead  109  even if the selected position is outside the video camera movable area. Also, an error message is displayed although the video camera  101  does not move, so the user can instantly know that the selection is an error. 
   It is readily possible to determine that the selected place is outside the video camera movable area, when the system controller  105  calculates the coordinates of the selected place and detects that the calculated coordinates are outside the video camera movable area  112   b  and inside the imaging enable area  112   a . More specifically, a method in the third embodiment is applicable. If the system controller  105  detects that the selected place is outside the video camera movable area, the message described above can be displayed on the display  100  via the image controller  103 . 
   In the above embodiment, the video camera  101  is not operated if the selected place is outside the video camera movable area. However, the following effect can be obtained by operating the video camera controller  102  to set zooming of the video camera  101  to the widest-angle without panning and tilting the camera. That is, the user selected the place because he or she wanted to see the place. Therefore, it is desirable that the selected place be displayed even though the place is not displayed in the center of the screen. If the optical axis of the video camera  101  positions at the edge portion of the video camera movable area  112   b , an image of the selected place (outside the camera movable area, in this case) can sometimes be displayed by setting zooming of the camera to the widest-angle. If this is the case the desire of the user is satisfied. 
   Third Embodiment 
   In this embodiment, the content in step S 235  of  FIG. 23  in the second embodiment is changed. In the second embodiment, as described above, even if the place selected by the user is outside the video camera movable area, the user selected the place because he or she wanted to see the place. Therefore, it is desirable that the selected place be displayed even though the place is not displayed in the center of the screen. In this embodiment, this desire is positively satisfied. This embodiment will be described in detail below with reference to the accompanying drawings. Note that the system configuration is identical with that of the second embodiment shown in  FIG. 19  and the GUI is also similar to that of the second embodiment shown in  FIG. 20 , and so detailed descriptions thereof will be omitted. 
     FIGS. 24A and 24B  illustrate operations on a video camera control screen  112 .  FIG. 24A  shows a normal operation in which the user selects a position inside a video camera movable area  112   b  as a new object to be sensed.  FIG. 24B  shows a case where the user selects a position outside the video camera movable area  112  as a new object to be sensed. 
   Referring to  FIG. 24A , a cursor  119  is moved by an operation unit  106  such as a mouse to select a predetermined position, a coordinate point  120  in this case, thereby moving an imaging range display area from an area  112   c  to an area  112   d . An image in this new area  112   d  is displayed on an image display screen  111  ( FIG. 20 ). In this case the zoom magnification is not altered and the imaging direction of a video camera  101  is so changed that the selected coordinate point  120  is displayed in the center of the screen. 
   In  FIG. 24B , as in the case of  FIG. 24A , the sensing range display area is moved from the area  112   c  to the area  112   d  by selecting the coordinate point  120 . Since the selected coordinate point  120  is outside the video camera movable area  112   b , it is not possible to change the sensing direction of the video camera  101  toward that position. Therefore, an intersection  123  of a straight line  122  connecting a central coordinate point  121  of an imaging enable area  112   a  and the selected coordinate point  120  and the frame of the video camera movable area  112   b  is set as a new imaging screen center. However, if the camera direction is changed without changing the zoom magnification, the selected coordinate point  120  (in  FIG. 24B ) sometimes does not come into the sensing range as indicated by the positional relationship between the sensing range display area  112   d  and the selected coordinate point  120 . Therefore, the zoom magnification is minimized (to the widest angle). By the above control, the selected coordinate point  120  is contained in an area  112   e  broader than the sensing range display area  112   d , and this makes sensing at the selected coordinate point  120  possible. 
   Details of the operation of the video camera control method in this third embodiment will be described below with reference to  FIGS. 25 and 26 .  FIG. 25  illustrates the sensing enable area  112   a  as a plane having a size of m×n. Coordinates are written in this plane, and the plane is divided into a plurality of areas. Reference numerals in  FIG. 25  are the same as in  FIG. 24B .  FIG. 26  is a flow chart showing the operation of a system controller  105 . Corresponding step numbers are given in parentheses. 
   The user operates the operation unit  106  to move the cursor  119  in a video camera control window  110  on a screen  110   a  of a display  100 , selecting a place to be sensed (step S 100 ). 
   The system controller  105  detects coordinates (Xp,Yp)  120  of the position of the cursor  119  when the place to be sensed is selected in step S 100  (step S 101 ). 
   The system controller  105  checks which of areas A, B, C, D, and E the selected coordinate point (Xp,Yp)  120  belongs to (step S 102 ). 
   If the system controller  105  determines in step S 102  that the selected coordinate point (Xp,Yp)  120  is within the area A, i.e., the video camera movable area  112   b , it is unnecessary to change the zoom value. Accordingly, the system controller  105  calculates the moving amount of the video camera (step S 103 ). 
   On the other hand, if the system controller  105  determines in step S 102  that the selected coordinate point (Xp,Yp)  120  is in any of the areas B, C, D, and E outside the video camera movable area  112   b , the system controller  105  calculates coordinates of a new sensing center  123  (step S 104 ). For example, if it is determined that the selected coordinate point (Xp,Yp)  120  is in the area B as illustrated in  FIG. 25 , the new sensing center (the position of the optical axis of the video camera  101 )  123  is calculated as follows. 
   That is, assuming the coordinates of the center in the sensing enable area  112   a  are (Xc,Yc), the straight line  122  passing the selected coordinate point (Xp,Yp)  120  and the central coordinate point (Xc,Yc)  121  is given by
 
( y−Yc )( Xp−Xc )=( x−Xc )( Yp−Yc )
 
Since the frame of the video camera movable area  112   b  in contact with the area B is
 
y=Yb
 
the coordinates of the new imaging center  123  as an intersection of the straight line  122  and the frame of the video camera movable area  112   b  are calculated by
 
((Yb−Yc)(Xp−Xc)/(Yp−Yc)+Xc,Yb)
 
   The system controller  105  then calculates the amount of movement to the new sensing center  123  calculated in step S 104 . If an operation of minimizing the zoom magnification (to the widest angle) is also to be performed, the system controller  105  performs a calculation for the operation (step S 105 ). 
   Subsequently, the system controller  105  checks whether the video camera  101  as an object to be controlled is connected to a video camera controller in a remote place or can be controlled by the controller  105  (step S 106 ). 
   If the system controller  105  determines in step S 106  that the video camera  101  is connected to a video camera controller in a remote place, the system controller  105  transmits the video camera control information calculated in step S 103  or S 105  to the video camera controller in the remote place via a communication controller  104  (step S 107 ). 
   If the system controller  105  determines in step S 106  that the video camera  101  can be controlled by the controller  105 , the system controller  105  moves the camera direction and changes the zoom magnification of the video camera  101  on the basis of the control information of the video camera  101  calculated in step S 103  or S 105  (step S 108 ). 
   By repeating the operation from step S 100  to step S 108  described above, it is possible to pick-up an image of a given object located in the sensing enable range of the video camera  101  as an object to be controlled. 
   In the processing of this embodiment, interrupt is accepted. Interrupt occurs when the user completes the operation of the system (step S 109 ), and the processing is ended. 
   In this embodiment as described above, even if a place selected by the user is outside the video camera movable area, the video camera  101  is moved to the limit toward the position selected by the user and stopped at that limiting position, and an image corresponding to the field of view of the video camera  101  is displayed. Accordingly, no additional load is applied on the camera driver and an image of the selected place or of the selected place and its vicinity is taken (displayed). Consequently, the desire of the user to see the selected place can be satisfied. Also, the camera cannot be pointed to the designated imaging inhibited area even if the user attempts to aim the camera in that direction. 
   Furthermore, when the zoom magnification is minimized (to the widest angle), an image of the selected place can be reliably taken (displayed). 
   Fourth Embodiment 
   The fourth embodiment is obtained by further improving the third embodiment. This fourth embodiment will be described below with reference to the accompanying drawings. The configuration, GUI, and video camera control screen of a video camera controller are the same as in the second and third embodiments, and so  FIGS. 19 ,  20 , and  21  are again used for these parts. 
   An outline of the operation of a video camera control method according to the fourth embodiment will be described with reference to  FIG. 27 .  FIG. 27  shows an operation on the video camera control screen,  FIG. 21 . Note that an operation when the user selects a video camera movable area as a new object to be imaged is the same as the operation,  FIG. 24A , explained in the third embodiment, and so a detailed description thereof will be omitted. 
     FIG. 27  shows an example when the user selects a position outside the video movable area as a new object to be sensed. In  FIG. 27 , it is impossible to change the direction of a video camera  101  such that a selected coordinate point  130  comes to the center of the screen, since the selected coordinate point is outside a video camera movable area  112   b . Therefore, a point  131  on the frame of the video camera movable area  112   b , which is closest to the selected coordinate point  130 , is set as the center of a new sensing range. However, if the camera direction is changed without changing the zoom magnification, the selected coordinate point  130  sometimes does not come into the sensing range as indicated by the positional relationship between a sensing range display area  112   d  and the selected coordinate point  130 . Therefore, the zoom magnification is minimized (to the widest angle). By the above control, the selected coordinate point  130  is included in a sensing range display area  112   e , and this makes scene sensing possible. 
   Details of the operation of the video camera control method according to the fourth embodiment will be described below with reference to  FIGS. 28 and 29 .  FIG. 28  illustrates a sensing enable area  112   a  as a plane having a size of m×n. Coordinates are written in this plane, and the plane is divided into a plurality of areas. Reference numerals in  FIG. 28  are the same as in  FIG. 27 .  FIG. 29  is a flow chart showing the operation of a system controller  105 . 
   The user operates an operation unit  106  to move a cursor  119  in a video camera control window  10  on a screen  100   a  of a display  100 , selecting a place to be sensed (step S 200 ). 
   The system controller  105  detects the coordinates (Xp,Yp) of the position of the cursor  119  when the place to be sensed is selected in step S 200  (step S 201 ). 
   Subsequently, the system controller  105  checks which of areas A, B, C, D, E, F, G, H, and I the selected coordinate point  130  (Xp,Yp) belongs to (step S 202 ). 
   If the system controller  105  determines in step S 202  that the selected coordinate point (Xp,Yp) is within the area A, i.e., the video camera movable area  112   b , it is not necessary to change the zoom value. Accordingly, the system controller  105  calculates only the moving amount of the video camera  101  (step S 203 ). 
   If the system controller  105  determines in step S 202  that the selected coordinate point  130  (Xp,Yp) is within any of the areas B, C, D, E, F, G, H, and I outside the video camera movable area  112   b , the system controller  105  calculates the coordinates of the center  131  of the new sensing range (step S 204 ). A method of calculating the center  131  of the new sensing range when it is determined that the selected coordinate point  130  (Xp,Yp) is in the area B as illustrated in  FIG. 28  is as follows. 
   The point  131  on the frame of the video camera movable area  112   b , which is closest to the selected coordinate point  130  (Xp,Yp), can be easily obtained by
 
(Xp,Yb)
 
since the point  131  is the intersection of a boundary line
 
y=Yb
 
between the area B and the video camera movable area  112   b  and a perpendicular
 
x=Xp
 
from the selected coordinate point  130  (Xp,Yp) to the straight line y=Yb. That is, when the area B is selected, the X coordinate of the new position of the video camera  101  can be determined from the selected coordinate point  130  (Xp,Yp), and the Y coordinate is unconditionally Yb. Similarly, when the area F is chosen the Y coordinate is unconditionally Yf. When the areas D and H are chosen, the X coordinates are unconditionally Xd and Xh, respectively, although the Y coordinates are respective designated values.
 
   When the selected coordinate point  130  belongs to any of the areas C, E, G, and I, the coordinate point at the corner of the video camera movable area  112   b , which is closest to the selected coordinate point  130 , is unconditionally set as the new center point  131  without performing the above calculations. For example, if the coordinate point (Xp,Yp) is contained in the area C, a corner point  133  is set as the imaging center. 
   The system controller  105  then minimizes the zoom magnification (to the widest angle) and calculates the amount of movement to the new center point  131  calculated in step S 204  (step S 205 ). 
   Subsequently, the system controller  105  checks whether the video camera  101  as an object to be controlled is connected to a video camera controller in a remote place or can be controlled by the controller  105  (step S 206 ). 
   If the system controller  105  determines in step S 206  that the video camera is connected to a video camera controller in a remote place, the system controller  105  transmits the video camera control information calculated in step S 203  or S 205  to the video camera controller in the remote place via a communication controller  104  (step S 207 ). 
   If the system controller  105  determines in step S 206  that the video camera  101  can be controlled by the controller  105 , the system controller  105  changes the camera direction and the zoom magnification of the video camera  101  on the basis of the control information of the video camera  101  calculated in step S 203  or S 205  (step S 208 ). 
   By repeating the operation from step S 200  to step S 208  described above, it is possible to take an image of a given object located in the sensing enable range of the video camera  101  as an object to be controlled. 
   In the processing of this embodiment, interrupt is accepted. Interrupt occurs when the user completes the operation of the system (step S 209 ), and the processing is ended. 
   In this embodiment as described above, even if a place selected by the user is outside the video camera movable area, the video camera  101  is moved to the limit toward the position selected by the user and stopped at that limiting position, and the zoom magnification of the video camera  101  is minimized (to the widest angle). Accordingly, no additional load is applied on the camera driver and an image of the selected place is picked-up (displayed). Consequently, the desire of the user to see the selected place can be satisfied. Also, the camera cannot be pointed in an imaging inhibited area. 
   In the systems of the first to fourth embodiments as described above, even if a place selected by the user is outside the video camera movable area, the driver for changing the direction of a video camera is not damaged. Also, the user can limit the camera movable range, and the camera cannot be pointed in that direction. 
   Additionally, the user can instantly know that the selection is an error even though the video camera does not move. 
   Furthermore, even if a place selected by the user is outside the video camera movable area, the video camera is moved to the limit toward the position selected by the user and stopped at that limiting position, and an image corresponding to the view angle of the video camera is displayed. Accordingly, no additional load is applied on the camera driver and an image of the selected place or of the selected place and its vicinity is picked-up (displayed). Consequently, the desire of the user to see the selected place can be satisfied. 
   An image of the selected place can be reliably picked-up (displayed). 
   An area outside the video camera movable area can be processed as four portions, and this facilitates the processing. 
   An area outside the video camera movable area can be divided into a plurality of areas, and each individual area can be unconditionally processed. 
   Fifth Embodiment 
   The fifth embodiment of the present invention will be described in detail below with reference to the accompanying drawings. This embodiment relates to a technique by which an object to be sensed is changed without moving a camera in the systems of the first to fourth embodiments. 
     FIG. 30  is a block diagram showing an outline of the configuration of the fifth embodiment of the present invention. Referring to  FIG. 30 , a CPU  22  for controlling the overall system, a main storage  24  of the CPU  22 , a bit map display  35 , a mouse  28 , a network interface  36 , and a frame memory  320  are connected to a bus  38 . 
   A video capture unit  326  converts an output video signal from a video camera  10  into a digital signal and outputs the signal to the frame memory  320 . An object lens of the video camera  10  is a high-resolution, wide-angle lens capable of picking-up an image of large area within the field of view of the lens. An image pick-up means of the video camera  10  is desirably a Highvision camera or a device with a higher resolution. 
     FIG. 31  shows an example of the display screen of the display  35 . A window system capable of displaying a plurality of overlapped windows is operating on the display  35 . In  FIG. 31 , an image display window  330  and an operation panel  332  are displayed. The image display window  330  displays a portion of an image picked-up by the video camera  10 . The operation panel  332  is used to designate which portion of the input image from the video camera  10  is to be displayed on the image display window  330 , and to designate the magnification at which the selected image portion is displayed. The operation panel  332  includes a button  338  for designating an imaging inhibited area and a clear button  339 . The operation panel  332  further includes a position designation panel  334  and a magnification designation panel  336 . The position designation panel  334  is used to designate a portion of the input image from the video camera  10  which is to be displayed in the image display window  330 . The magnification designation panel  336  is used to designate the magnification of the image displayed in the image display window  330 . 
   In this embodiment, designation of the imaging inhibited area is done in the same manner as in the fourth embodiment. Therefore, a detailed description of a procedure of the designation will be omitted. 
     FIG. 32  shows the relationship between an image (input image) picked-up by the video camera  10  and stored in the frame memory  320  and an image (display image) displayed in the image display window  330 . Reference numeral  340  denotes an input image, i.e., an image which is picked-up by the video camera  10  and stored in the frame memory  320  by the video capture unit  326  and from which an imaging inhibited area is excluded. Reference numeral  342  denotes an area extracted from the input image  340  and displayed in the image display window  330 . If the extraction area  342  is outside the input image  340 , fixed-color data or the like is displayed in this outside portion. This allows a user to readily recognize on the screen that he or she is attempting to see a portion outside the sensing range or a portion outside the imaging inhibited area. Therefore, except in such a case or portion, the extraction area  342  generally coincides with the display image. 
   Assuming that the vertical and horizontal directions on the imaging screen of the camera  10  are  x  and  y  axes, respectively, the angles in the  x  and  y  directions are represented by θ and ø, respectively, and θ=0, ø=0, x=0, and y=0 in the center of the input image, the central coordinates (xl,yl) of the display image are represented by
 
xl=L tan θ
 
yl=L tan ø
 
where L is a constant. The display area to be extracted from the input image is determined by this origin coordinate point (xl,yl) and the display magnification. The higher the display magnification the smaller the vertical and horizontal dimensions of the extraction area.
 
   The pixel density of the image extracted from the extraction area  342  is so converted as to meet the number of pixels in the image display window  330 . Assuming, for example, that the numbers of pixels in the image display window  330  are H (vertical)×W (horizontal) and the numbers of pixels in the area extracted from the input image are h (vertical)×w (horizontal), H and W rarely equal h and w, respectively. Generally, the pixel data in the extraction range is interpolated and thinned so as to meet the number of pixels in the image display area of the image display window  330 . Various known methods are usable as this pixel density conversion method. 
   The center (xl,yl) of the extraction area  342  can be freely designated by operating four-direction keys on the position designation panel  334  by using the mouse. Also, an arbitrary display magnification can be designated on the magnification designation panel  336 . The vertical (h) and horizontal (w) dimensions of the extraction range  342  are determined by the magnification designated on the magnification designation panel  336  and the vertical and horizontal dimensions of the image display window  330 . 
   The image in the extraction area  342  is displayed on the display  35  or transmitted to a remote place via the network interface  36 . 
   In this embodiment, tilt(θ), pan(ø), and zoom(z), the same commands as used in a camera operation command system, are used in a command system for changing the center of the extraction area  342 . Tilt(θ) is a command for tilting in the vertical direction, pan(ø) is a command for panning in the horizontal direction, and zoom(z) is a command for zooming. 
   That is, the tilt command is assigned to the vertical keys on the position designation panel  334 . While these keys are depressed, the CPU  22  increases or decreases the angle θ to generate a tilt(θ) command. The pan command is assigned to the horizontal keys on the position designation panel  334 . While these keys are depressed, the CPU  22  increases or decreases the angle ø to generate a pan(ø) command. The zoom command is assigned to the scroll bar on the magnification designation panel  336 . In accordance with the movement of this scroll bar, the CPU  22  generates a zoom(z) command of a magnification  z  meeting the movement. 
   The tilt and pan commands change the center of the area  342  extracted from the frame memory  320 , and the zoom command changes the size of the extraction area  342 . These commands can be transmitted to a remote plate via the network  36 . That is, it is possible to remotely change the area extracted from a frame memory in an apparatus with the same configuration as in  FIG. 30  installed in a distant place. 
     FIG. 33  shows the flow of a procedure from imaging to image display in this embodiment. A dynamic image can be reproduced and displayed if this procedure is executed within one frame cycle of a dynamic image. 
   Referring to  FIG. 33 , steps S 334  and S 335  correspond to a control procedure done by a video communication controller  20 . When an image is input from the camera  10  (step S 331 ), the video capture unit  326  writes the image data into the frame memory  320  (steps S 332  and S 333 ). In accordance with the tilt angle, pan angle, and zoom magnification designated on the panels  334  and  335 , the extraction area  342  is determined and the image is extracted as shown in  FIG. 32  (step S 334 ). The extracted image is converted to meet the size of the window  330  in which the image is to be displayed (step S 335 ). The converted image is then output and displayed (step S 336 ). 
   The above procedure is executed for a local camera or by a client in a remote place. To operate a camera in a distant place, the tilt, pan, and zoom commands are generated and transmitted to a controller of the camera in that place. 
   If the pan, tilt, and zoom operations are performed for the same camera, it is only necessary to execute steps S 334  and S 335 . 
   As described above, the display direction and width can be changed by electronically changing the area  342  extracted from the frame memory  320 . Accordingly, it is possible to obtain essentially the same effect as when the direction and the zoom magnification of a single camera are instantaneously changed. 
   Remote control is made possible by transmitting an image extracted from the extraction area  342  of the frame memory  320  to a terminal in a distant place via the network and transmitting the individual commands described above from the terminal in the distant place. The remote control is basically the same as when panning, tilting, and zooming of a camera are remotely operated. 
   In this embodiment, an image extracted from the extraction area  342  of the frame memory  320  is displayed in the image display window  330  of the bit map display  35  and output to the network where necessary. However, it is obvious that the image can also be written into a file. That is, any output form is usable as long as the processing speed is sufficiently high. The image also can be compressed by the JPEG or MPEG coding scheme before being transferred. 
   It is also evident that if the video camera  10  includes a memory means which can be externally controlled, this memory means can be used instead of the frame memory  320 . 
   Although one extraction area  342  is set for an input image in the above embodiment, a plurality of extraction ranges also can be set. If this is the case, each extraction range is provided with a camera window having an image display window for displaying an image extracted from the extraction range and an operation panel for setting the extraction area.  FIG. 34  shows an example of a screen having four camera windows  350 ,  352 ,  354 , and  356 .  FIG. 35  shows an example of setting of corresponding extraction areas  358 ,  360 ,  362 , and  364  in the frame memory  320 . Images extracted from the extraction areas  358 ,  360 ,  362 , and  364  are displayed in image display windows  350   a ,  352   a ,  354   a , and  356   a  in the camera windows  350 ,  352 ,  354 , and  356 , respectively. Operation panels  350   b ,  352   b ,  354   b , and  356   b  in the camera windows  350 ,  352 ,  354 , and  356  are used to operate the positions and sizes of the extraction ranges  358 ,  360 ,  362 , and  364 , respectively. 
   The correspondence between the camera windows  350 ,  352 ,  354 , and  356  and the extraction areas  358 ,  360 ,  362 , and  364  is managed by a table as illustrated in  FIG. 36 . Virtual camera numbers directly correspond to the extraction areas  358 ,  360 ,  362 , and  364 . In accordance with an operation on the operation panels  350   b ,  352   b ,  354   b , and  356   b , the corresponding values of θ, ø, and zoom magnification in the row of the corresponding operation panel ID are updated, and the corresponding extraction area is reset in accordance with these new values. 
     FIG. 37  is a flow chart of an operation of capable of setting a plurality of extraction areas. This flow chart is formed by extending the flow chart shown in  FIG. 33  so as to correspond to each entry in the table in  FIG. 36 . The flow chart in  FIG. 37  differs from the flow chart in  FIG. 33  only in that loop processing is added. Assuming the frame rate of a dynamic image is F (frame/sec), N images can be extracted from an input image from a single camera so long as a procedure from step S 311  to step S 319  is executed within 1/F second. To transfer the images to the network, virtual camera numbers are added to the image data to be transmitted in order to be able to identify which image is extracted from which extraction area. A plurality of images with different virtual camera numbers can be displayed as if images from a plurality of cameras are displayed. 
   In this way it is possible by physically using a single camera to obtain images in various directions at various zoom magnifications, as if a plurality of cameras were used. It is of course possible to independently and instantaneously change the directions and zoom magnifications of the individual images. 
   By the use of a graphical user interface shown in  FIG. 38 , one or more extraction areas can be set more visually. Reference numeral  370  denotes an operation window for setting extraction areas. The size of this operation window is proportional to the size of an image obtained by excluding an imaging inhibited area from an input image to the frame memory  320 . In the window  370 , rectangular frames  372 ,  374 ,  376 , and  378  indicating extraction areas with desired positions and sizes are set. These rectangular frames  372  to  378  are expandable and movable within the area of the window  370 . The position and size of each rectangular frame in the window  370  represent the position and size of the corresponding extraction area. When the rectangular frames  372  to  378  are initially set, the points at opposing corners of each rectangular frame are designated by using, e.g., a mouse. As shown in  FIG. 38 , a portion of an input image to which each extraction area corresponds to can be clearly seen. 
   As can be readily understood from the above description, in this embodiment the same effect as one obtainable when a plurality of cameras are used can be obtained by physically using a single camera. That is, it is possible to instantaneously change the direction and the zoom magnification of the virtual camera and to simultaneously obtain images in various directions at various zoom magnifications. 
   This embodiment can be combined with any of the second to fourth embodiments. 
   In a case where the second embodiment is applied, if a designated extraction frame overlaps an imaging inhibited area, this designation is neglected and an error message is displayed. 
   In a case where the third or fourth embodiment is applied, if a designated extraction frame overlaps an imaging inhibited area, the entire extraction frame is moved by an amount corresponding to the overlapped portion. More specifically, the extraction frame is moved toward the inside of an input image by amounts corresponding to the overlapped lengths in both the X- and Y-axis directions. 
   The systems of the first to fifth embodiments described above can also be realized by connecting a camera to a general-purpose apparatus such as a personal computer and supplying programs for performing the control in these embodiments from a storage medium. 
   In this case, the program codes read from the storage medium realize the functions according to the embodiments, and the storage medium storing the program codes constitutes the invention. 
   Further, the storage medium, such as a floppy disk, a hard disk, an optical disk, a magneto-optical disk, CD-ROM, CD-R, a magnetic tape, a non-volatile tape memory, and ROM can be used for providing the program codes. 
   Furthermore, besides aforesaid functions according to the above embodiments are realized by executing the program codes which are read by a computer, the present invention includes a case where an OS (Operating System) or the like working on the computer performs a part or entire processes in accordance with designations of the program codes and realizes functions according to the above embodiments. 
   Furthermore, the present invention also includes a case where, after the program codes read from the storage medium are written in a function expansion card which is inserted into the computer or in a memory provided in a function expansion unit which is connected to the computer, CPU, or the like contained in the function expansion card or unit performs a part or entire process in accordance with designations of the program codes and realizes functions of the above embodiments. 
   In a case where the present invention is applied to the aforesaid storage medium, the storage medium stores program codes corresponding to the flowcharts described in the embodiments.