Abstract:
A method and system of rendering buildings in three-dimensional space first renders a respective floor, then adds objects and finally walls to bound each of the floors. The result, a three-dimensional rendering of a building illustrates the position of objects within the building in addition to presenting the overall shape of the building. The rendering can be discontinuously rotated, about an axis, in response to user inputs.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This is a continuation-in-part of U.S. patent application Ser. No. 11/274,443 filed Nov. 15, 2005, entitled “SYSTEMS AND METHODS FOR RENDERING BUILDING SPACES” which is incorporated by reference herein. 

   FIELD 
   The invention pertains to the creation and presentation of three-dimensional images on two-dimensional graphical displays. More particularly, the invention pertains to systems and methods for generating three-dimensional renderings of building spaces and rotating same with stepped rotation on two-dimensional graphical display devices. 
   BACKGROUND 
   Known software and hardware is available for rendering various types of three-dimensional images including building spaces. Known methods and systems at times do not clearly or accurately depict the location of objects in a rendered image of a building. Further, at times the positional relationships of objects to one another, when the objects are located on multiple floors, are not always clearly depicted. 
   Known systems include the use of graphics hardware to attempt to generate accurate three-dimensional images. Other known methods seek to improve accuracy by rendering the back walls first. The objects in the floors are then drawn. Finally, the front walls are rendered. Such processes can suffer from performance penalties other drawbacks. Some systems use animation software to implement rotations of the displayed spaces. 
   Known systems and methods often do not accurately render transparency and depth simultaneously in a three-dimensional structure unless the polygons used to create the images are rendered from back to front. However, in such processes, sorting of polygons can be either inefficient or unfeasible due to time and depth processing requirements. Thus, errors can arise from currently used techniques for transparency which ignore depth or techniques for testing depth which ignore transparency. 
   Increasingly, 3D models of large buildings are being used in graphical displays to support situation awareness in a variety of domains including firefighting, building security, asset tracking and HVAC management. For example, a semi-transparent 3D model of a building can be used to provide a birds-eye perspective view of the building, outside looking in, and the locations of activated smoke and heat detectors in three-dimensional space. From such a display, the firefighter can comprehend the spread of the fire at a glace, particularly the vertical spread between floors of the building. Also, it is a very intuitive way for the firefighter to visualize a path to the fire and to view the locations of his or her team members. 
   One of the advantages of 3D graphics for buildings is the possibility created for the user to view the building, outside looking in, from different perspectives. Rotating the building on its axis around a 360 degree radius reveals new and valuable relationships between objects embedded in the building and features such as doors, elevators, water sources, etc. However, as noted above, continued rotation of the building in graphics requires animation and is computationally demanding. 
   Rotation also can give rise to problems of user spatial disorientation (“What side of the building am I looking at now? How do I get back to the front door or lobby side?”) A method clearly is needed that will provide some of the advantages of perspective change created by 360 degree rotation while keeping the computational load to a minimum and providing orientation anchors for the user. 
   There thus continues to be an ongoing need for systems and methods for rendering and rotating multi-dimensional building spaces without requiring animation software. Additionally, it would be desirable to be able to provide orientation indicators for the user so as to minimize partial disorientation. Finally, it will be preferable to be able to continue to accurately locate objects on the respective floor or floors as well as accurately render transparency and depth simultaneously without having to sort polygons. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is block diagram of a system in accordance with the invention; 
       FIGS. 2A , B taken together are a flow diagram of a method in accordance with the invention; 
       FIG. 3  is an image presented by the method of  FIGS. 2A , B; 
       FIG. 4  illustrates another step of the method of  FIGS. 2A , B; 
       FIG. 5  illustrates a third step of the method of  FIGS. 2A , B; 
       FIG. 6  illustrates another step of the method of  FIGS. 2A , B; 
       FIG. 7  illustrates yet another step of the method of  FIGS. 2A , B; 
       FIG. 8  illustrates yet another step of the method of  FIGS. 2A , B; 
       FIG. 9  illustrates yet another step of the method of  FIGS. 2A , B; 
       FIG. 10  illustrates yet another step of the method of  FIGS. 2A , B; 
       FIG. 11  illustrates yet another step of the method of  FIGS. 2A , B; and 
       FIG. 12  illustrates yet another step of the method of  FIGS. 2A , B. 
   

   DETAILED DESCRIPTION 
   While this invention is susceptible of embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
   A method in accordance with the invention, as described below, provides stepped rather than continuous rotation of an image of a building about its axis. The present method and system are advantageous in that eliminating the need for continuous animation in connection with the rotation substantially reduces computational demands. Additionally, indicia are provided to maintain user orientation. 
   In one aspect of the invention, a user can rotate an image of a building about its axis in fixed steps on the order of 30 degrees or 60 degrees to the right or left. The intermittent or stepped rotation is carried out by means of a plurality of command buttons presented on the same display as image of the building is being presented on. For example, a complete trip around the exterior periphery of a building, looking into a selected floor thereof, can be carried out in six steps using a sixty degree rotation button. Alternately, it can be carried in twelve steps using a 30 degree rotation button. 
   Orientation of the operator or user is reinforced or supported by the availability of a “front” button which immediately rotates the image such that the user use the image from a front or forward orientation. 
   In another aspect of the invention, the user or operator can switch between two dimensional floor plan views or three dimensional perspective-type views illustrating multiple floors. When switching back and forth between two dimensional views or three dimensional views, orientation is reinforced or supported since the new view has the same orientation as the prior view. 
     FIG. 1  illustrates a system  10  which might be distributed throughout a plurality of floors of a building B 1  for purposes of monitoring various conditions throughout the building. Representative conditions could include fire, smoke, gas, operation of a HVAC systems, illumination systems, and/or security systems all without limitation. 
   System  10  could incorporate a plurality of ambient condition detectors scattered throughout the building indicated generally at  14  for purposes of monitoring various conditions throughout the building of B 1 . Signals that pertain to outputs from detectors  14  could be coupled to a fire situation control and display unit  18 . The unit  18  could be in wired or wireless communication with various of the detectors  14  scattered throughout the building B 1 . 
   Information pertaining to conditions within the building B 1  could be presented one or more local visual displays. Such displays could provide information pertaining to the state of one or more of the members  14   i  of the plurality  14  of ambient condition detectors. 
   Unit  18  can be implemented with control circuits  20   a  which could include one or more programmable processors. It will be understood that the processors need not all be located physically near one another. They could communicate via one or more networks. 
   Unit  18  can also include control and monitoring software  20   b  executable by one or more of the processors of control circuits  20   a . The software  20   b  implements communications with the plurality of ambient condition detectors  14 , as well as other displaced devices via a wired and/or wireless medium indicated generally at  20   c - 1 . Communications can be provided to other sites via a wired or wireless medium  20   c - 2 . 
   The unit  18  can also include software  20   d , discussed in more detail subsequently, for presenting one or more renderings of the building B 1 . The renderings in 2D or 3D form, can be presented locally on a two-dimensional visual display unit  20   e . The unit  20   c  can be viewed by first responders in the vicinity for purposes of understanding the layout of the building B 1 , including location of stairways and elevators in the building, location and arrangement of the members of the plurality of detectors  14 . Those detectors which are emitting indications of an alarm condition can be highlighted. 
   As those of skill in the art will understand, a variety of software is available to create renderings of the various floors of the building B 1 . A preferred system and process are disclosed and claimed in the parent hereto, U.S. patent application Ser. No. 11/274,443 incorporated by reference herein. Other forms of rendering come within the spirit and scope of the invention. 
     FIGS. 2A ,  2 B taken together illustrate a method  100  in accordance with the invention. In a step  102  a two dimensional plan view of a selected floor, see  FIG. 3 , is illustrated on a display  20   e  for the user. As illustrated in  FIG. 3 , two dimensional plan views are activated by control element or button  40   a . Three dimensional views are activated by a control element or button  40   b.    
     FIG. 3  illustrates a plan view of the third floor of the building B 1  looking toward the front of the building as indicated by orientation indicator  40   c . The floor to be displayed can be selected from a plurality of control elements or buttons indicated generally at  42 . 
   An alarm list can be displayed via control element or button  46 . 
   In a step  104  the user can press the “3D” control element or button  40   b . In response thereto, the software  20   d  displays a rendering of the building B 1  indicated in  FIG. 4 , step  106 . As illustrated in  FIG. 4 , the viewer or operator continues to see an image looking to the front of the building. Indicators  44   a  and  44   b  at the right side of the display of  FIG. 4  can be used to change the viewing perspective or “pitch” of the view. 
   The floor selected from the plurality  42 , namely floor  3 , is emphasized in the display of  FIG. 4 . The display of  FIG. 4  not only presents the configuration of the third floor, as well floors above and below that, but it displays location of a variety of detectors, alarm indicting devices, elevators, stairs and the like all without limitation. 
   In addition to the display specifying buttons  40   A, B  the display of  FIG. 4  also provides additional control buttons  40 - 1  . . .  40 - 5  which can be used to control the orientation and produce rotation of the image present on the display  20   e . For example, if the user activates button  40 - 2 , step  110 , requesting 30 degree clockwise rotation, the rendering software  20   d  rotates the image of  FIG. 4  30 degrees clockwise as illustrated in  FIG. 5 , step  112 . The display of  FIG. 5  presents the building B 1  with the requested orientation while still carrying and showing the appropriate relative locations of the various detectors, alarm output devices, stairways, elevators and the like all without limitation. 
     FIG. 6  illustrates the image of the building B 1  where the user has again activated the command or control button  40 - 2  requesting another 30 degree clockwise rotation which produces a total of 60 degrees of rotation relative to the front of the building. Alternately, instead of activating the button  40 - 2  twice, in step  116 , the user activate control element or button  40 - 1  requesting a sixty degree clockwise rotation of the image which in addition to the previously provided 30 degree rotation results in a total of a ninety degree rotation relative to the front of the building step  118 . 
   In the event that the user activates the “front” control element or button  40 - 3 , step  122 , the image of the building B 1  is rotated back to its original orientation with the user or operator viewing the image from the front of the building, see  FIG. 7 , step  124 . 
   As illustrated in  FIG. 8 , if the operator or user activates the control element or button  40 - 4 , step  128 , requesting a 30 degree counterclockwise rotation, the image of the building B 1  is rotated accordingly, and as illustrated in  FIG. 8 , continues to display the various detectors, output devices, stairways or elevators for example, with the appropriate relative location, step  130 . Similarly, if the user continues to activate the 30 degree counterclockwise rotation button or control element  40 - 4 , see  FIGS. 9 ,  10 , the image of the building B 1  presented on the display  20   e  will rotate counterclockwise with the requested 30 degree increments. 
   In the event that the user desires to view the building B 1  with the orientation at  FIG. 10  but relative to a different floor, another floor can be selected from the plurality  42  and displayed as illustrated in  FIG. 11 . Finally, if the user selects or activates  2 D display element or button  40   a , the selective floor, floor  6 , will be presented as a plan view, see  FIG. 12 , step  136  with the same orientation relative to the front of the building as previously presented in the last three dimensional view,  FIG. 11 . 
   As illustrated in  FIG. 12 , in the plan view the sixth floor includes the stair and elevator icons  50   a,b  and could include other icons such as detectors and alarm indicating output devices such as  48   a,b  with the proper orientation relative to floor  6  and also relative to the front of the building. It will also be understood that a variety of other symbols indicating other information of use or importance to first responders could also be incorporated into the displays of  FIGS. 3-12  including the locations of sprinkler heads, and which sprinkler heads have become active, if known. Other information includes which of detectors such as  48   a  are indicting an alarm condition. Other indicators of temperature or air quality could also be included in the images of  FIGS. 3-12  along with either color or numeric indicia indicative of the state of those particular detectors. All such variations come within the spirit and scope of the present invention. 
   From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.