Patent Publication Number: US-2023160694-A1

Title: Survey assistance system and survey assistance method

Description:
CROSS-REFERENCE TO RELATED APPLICATION, BENEFIT CLAIM, AND INCORPORATION BY REFERENCE 
     The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-190479 filed Nov. 24, 2021. The contents of this application are incorporated herein by reference in their entirely. 
     TECHNICAL FIELD 
     The present invention relates to a survey assistance system and a survey assistance method, more specifically, to a survey assistance system and a survey assistance method using an eyewear display device. 
     BACKGROUND ART 
     Conventionally, before performing a surveying work, a process chart and a drawing describing positions of instrument installation points, a measurement order, and surveying instruments to be used are prepared so that a desired surveying work can be performed as efficiently as possible in consideration of various circumstances including structural objects, visibility of the instrument installation points, reference points, etc., drawn on the drawing of a survey site, kinds and types, etc., of owned surveying instruments. At the survey site, the surveying work is performed while the process chart and the drawing are confirmed. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Published Unexamined Patent Application No. 2021-77127 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, performing a surveying work while confirming a process chart and a drawing at a survey site is burdensome. In particular, attention is required for an inexperienced worker in performing a survey at the time of selection and installation of surveying instruments to be used for surveys at instrument installation points. 
     Meanwhile, Patent Literature 1 discloses an eyewear display system which uses an eyewear display device, and manages 3D CAD (Three-Dimensional Computer Aided Design) design data of a site created in an absolute coordinate system and information on a position and a direction of the eyewear display device in the same coordinate space (system) so that the data created in the absolute coordinate system can be superimposed and observed on a site landscape. 
     The present invention was made in view of these circumstances, and an object thereof is to provide a survey assistance system which reduces a burden of confirming a process chart and a drawing at a survey site by using an eyewear display system. 
     Solution to Problem 
     In order to achieve the object described above, a survey assistance system according to a first aspect of the present invention is a survey assistance system including a measuring instrument including a communication unit and configured to measure a three-dimensional coordinate of a measuring object, an eyewear display device including a display, a relative position sensor configured to detect a position of the device itself, and a relative direction sensor configured to detect a direction of the device itself, and at least one processor configured to match coordinate spaces of the eyewear display device, the measuring instrument, and an absolute coordinate system, to enable information of a position and a direction of the eyewear display device and information of a position and a direction of data created in the absolute coordinate system to be managed in a space with an origin set at a common reference point, and configured to display an image in the absolute coordinate system created by the processor on the display to enable observation of the image superimposed on a site landscape observed with the eyewear display device being worn. The processor is configured to read out survey process data including at least instrument information of at least one surveying instrument to be used, three-dimensional position information of instrument installation points in the absolute coordinate system, and a measurement order of the instrument installation points, create a work assistance image based on the survey process data, and transmit the work assistance image to the eyewear display device and display the work assistance image on the display, and the work assistance image includes the instrument installation points and images of the surveying instrument to be used showing installed states at the instrument installation points, and the eyewear display device enables observation of the work assistance image by superimposing the work assistance image on the site landscape. 
     A survey assistance method according to a second aspect of the present invention is a survey assistance method using a measuring instrument including a communication unit and configured to measure a three-dimensional coordinate of a measuring object, and an eyewear display device including a display, a relative position sensor configured to detect a position of the device itself, and a relative direction sensor configured to detect a direction of the device itself. The method includes matching coordinate spaces of the eyewear display device, the measuring instrument, and an absolute coordinate system, to enable information of a position and a direction of the eyewear display device and information of a position and a direction of data created in the absolute coordinate system to be managed in a space with an origin set at a common reference point; displaying an image in the absolute coordinate system on the display to enable observation of the image superimposed on a site landscape observed with the eyewear display device being worn; reading-out survey process data including at least instrument information of at least one surveying instrument to be used, three-dimensional position information of instrument installation points in the absolute coordinate system, and a measurement order of the instrument installation points; creating a work assistance image based on the survey process data; and transmitting the work assistance image to the eyewear display device and displaying the work assistance image on the display, wherein the work assistance image includes the instrument installation points and images of the surveying instrument to be used showing installed states at the instrument installation points, and the eyewear display device enables observation of the work assistance image by superimposing the work assistance image on the site landscape. 
     Benefits of Invention 
     According to the aspects described above, a survey assistance system and a survey assistance method which reduce a burden of confirming a process chart and a drawing at a survey site can be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic external view of a survey assistance system according to a first embodiment of the present invention. 
         FIG.  2    is a configuration block diagram of the same survey assistance system. 
         FIG.  3    is a configuration block diagram of a surveying instrument (measuring instrument) constituting the same survey assistance system. 
         FIG.  4    is an external perspective view of an eyewear display device constituting the same survey assistance system. 
         FIG.  5    is a configuration block diagram of the same eyewear display device. 
         FIG.  6    is a configuration block diagram of a data management device constituting the above survey assistance system. 
         FIGS.  7 A and  7 B  are diagrams illustrating an example of survey process data to be used in the same survey assistance system. 
         FIG.  8    is a diagram illustrating an example of work assistance data to be used in the same survey assistance system. 
         FIG.  9    is a flowchart describing processing of a survey assistance method using the same survey assistance system. 
         FIG.  10    is a view describing detailed steps of synchronization of position and direction information (conversion of coordinate systems) to be performed as initial settings of the same processing. 
         FIGS.  11 A,  11 B,  11 C, and  11 D  are diagrams illustrating examples of work assistance image in the same survey assistance method. 
         FIG.  12    is a diagram illustrating an example of work assistance data to be used in a modification of the same survey assistance system. 
         FIG.  13    is a diagram illustrating an example of a work assistance image in a survey assistance method according to the same modification. 
         FIG.  14    is a diagram illustrating an example of work assistance data to be used in another modification of the survey assistance system. 
         FIG.  15    is a view illustrating an example of a work assistance image in a work assistance method according to the same modification. 
         FIG.  16    is a view illustrating an image of point cloud data that a general laser scanner can acquire. 
         FIGS.  17 A,  17 B, and  17 C  are diagrams illustrating a method for calculating an observation route in survey process data to be used in a survey assistance system according to a second embodiment of the present invention. 
         FIGS.  18 A and  18 B  are diagrams illustrating an example of a calculated observation route. 
         FIG.  19    is a configuration block diagram of an eyewear device and a data processing device of the survey assistance system according to the second embodiment. 
         FIG.  20    is a flowchart describing processing of a survey assistance method using the same survey assistance system. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, however, the present invention is not limited to these. The same configurations common to the respective embodiments and modifications are provided with the same reference signs, and overlapping descriptions will be omitted as appropriate. The same configurations in terms of hardware are provided with the same reference signs, and overlapping descriptions will be omitted as appropriate. 
     I First Embodiment 
     1. Configuration of Survey Assistance System  100   
       FIG.  1    is an external schematic view of a survey assistance system (hereinafter, simply referred to as “system”)  100  according to an embodiment of the present invention. The system  100  includes a surveying instrument  2 , an eyewear display device (hereinafter, referred to as “eyewear device”)  4 , and a data management device  6 .  FIG.  2    is a configuration block diagram of the system  100 . 
     2. Surveying Instrument  2  (Measuring Instrument) 
       FIG.  3    is a configuration block diagram of the surveying instrument  2  according to the present embodiment. The surveying instrument  2  includes a three-dimensional coordinate measuring unit  21 , a display unit  22 , an operation unit  23 , a storage unit  24 , an external storage device  25 , a communication unit  26 , and an arithmetic processing unit  27 . In the illustrated example, the surveying instrument  2  is a motor-driven total station to be installed at a survey site via a tripod. 
     The three-dimensional coordinate measuring unit  21  includes a distance-measuring unit  21   a , an angle-measuring unit  21   b , and a rotation driving unit  21   c . The distance-measuring unit  21   a  is an electro-optical distance meter that emits distance-measuring light and receives reflected light of the distance-measuring light, and obtains a distance to a measuring object by the arithmetic processing unit  27  based on received light signals of the reflected distance-measuring light and internal reference light obtained by partially splitting the emitted distance-measuring light. 
     The distance-measuring unit  21   a  is provided in a telescope that is rotated around two axes that are vertical and horizontal axes (V-V axis and H-H axis in  FIG.  1   ) by the rotation driving unit  21   c . The distance-measuring unit  21   a  measures angles of the measuring object by detecting a collimation direction of the telescope by the angle-measuring unit  21   b  that is a rotary encoder. 
     The display unit  22  is, for example, a liquid crystal display. The operation unit  23  includes a power key, numeric keys, a decimal key, a plus/minus key, an execution key, and a scroll key, etc., and enables a worker to operate the surveying instrument  2  and input information into the surveying instrument  2 . 
     The storage unit  24  is, for example, a hard-disc drive (HDD), and stores programs for executing functions of the arithmetic processing unit  27 . 
     The external storage device  25  is, for example, a memory card, etc., and stores various data acquired by the surveying instrument  2 . 
     The communication unit  26  is a communication control device such as a network adapter, a network interface card, a LAN card, or a Bluetooth (registered trademark) adapter, and connects the surveying instrument  2  to the eyewear device  4  and the data management device  6  by wire or wirelessly. The arithmetic processing unit  27  transmits and receives information to and from the eyewear device  4  and the data management device  6  through the communication unit  26 . 
     The arithmetic processing unit  27  is a control arithmetic unit including at least one processor (for example, CPU (Central Processing Unit)), and at least one memory (for example, SRAM (Static Random Access Memory)), DRAM (Dynamic Random Access Memory), etc. The processor reads out necessary data and program from the storage unit  24  into the memory and executes processing for realizing functions of the surveying instrument  2 . The arithmetic processing unit  27  measures a distance and angles to the measuring object by controlling the three-dimensional coordinate measuring unit  21 , and calculates three-dimensional position coordinates of the measuring object. 
     The surveying instrument  2  corresponds to the measuring instrument in claims accompanying the present description. The measuring instrument is not limited to the illustrated total station, and only has to be a surveying instrument including the communication unit  26  and a three-dimensional coordinate measuring unit capable of acquiring three-dimensional position coordinates of a measuring object. For example, the surveying instrument may be a laser scanner further including a turning mirror that causes distance-measuring light to scan 360° in the vertical direction in a vertical rotation driving unit of the three-dimensional coordinate measuring unit  21 , or, for example, a camera that includes two cameras and can acquire three-dimensional position coordinates of a measuring object by photo survey as illustrated in Patent Literature 1. 
     3. Eyewear Device  4   
       FIG.  4    is an external perspective view of the eyewear device  4 , and  FIG.  5    is a configuration block diagram of the eyewear device  4 . The eyewear device  4  is a wearable device to be worn on the head of a worker. The eyewear device  4  includes a display  41  and a control unit  43 . The control unit  43  includes a communication unit  44 , a relative position detection sensor  45 , a relative direction detection sensor  46 , a storage unit  47 , an operation switch  48 , and an arithmetic processing unit  49 . 
     The display  41  is a goggles-lens-shaped transmissive display that covers the eyes of a worker when the worker wears the eyewear device. As an example, the display  41  is an optical see-through display using a half mirror, and displays an image received by the control unit  43  by superimposing the image on a site landscape. Alternatively, the display  41  may be a video see-through display, and display an image received by the control unit  43  by superimposing the image on a front landscape image acquired in real time by a camera (not illustrated). As a projection method, a virtual image projection method may be used, or a retina projection method may also be used. In this way, a worker can observe a work assistance image created by survey process data  91  and work assistance data  92 , superimposed on a site landscape. The survey process data  91  and the work assistance data  92  will be described later. 
     When the display  41  is a video see-through display, its camera includes an image sensor, for example, a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), etc., and takes a front landscape image of the eyewear device  4  in real time. The image sensor has an orthogonal coordinate system with an origin set at a camera center, and local coordinates of each pixel are identified. A positional relationship between the camera center and a center of the eyewear device  4  is known, and the eyewear device  4  can convert a coordinate space of an image acquired by the camera into a coordinate space of the eyewear device  4  and manage the image. 
     The communication unit  44  is a communication control device similar to the communication unit  26 . The eyewear device  4  is connected wirelessly to the Internet and a communication network such as a mobile telephone network. The arithmetic processing unit  49  can transmit and receive information to and from the surveying instrument  2  and the data management device  6  through the communication unit  44  and the communication network. 
     The relative position sensor  45  detects a position (own position) of the eyewear device  4  in an observation site by performing radio determination from an antenna for a GNSS (Global Navigation Satellite System), a Wi-Fi (registered trademark) access point, and an ultrasonic oscillator, etc., installed at the observation site. 
     The relative direction sensor  46  consists of a combination of a triaxial accelerometer or gyro sensor and a tilt sensor. The relative direction sensor  46  detects a tilt (own direction) of the eyewear device  4  by defining the up-down direction as a Z-axis direction, the left-right direction as a Y-axis direction, and the front-rear direction as an X-axis direction. 
     The storage unit  47  is, for example, a memory card. The storage unit  47  stores programs for the arithmetic processing unit  49  to execute functions. 
     The operation switch  48  is, for example, as illustrated in  FIG.  4   , push buttons provided on an outer surface of the display  41 . The operation switch  48  includes, for example, a power button  48   a  for turning ON/OFF a power supply of the eyewear device  4 , and function buttons  48   b  that enable a worker to input selections and instructions, etc., in collaboration with display on the display  41 . In the present embodiment, as described later, by pressing a function button  48   b  at a position corresponding to a display button displayed on the display  41 , a worker is enabled to input a selection, confirmation, instruction, etc. 
     The arithmetic processing unit  49  is a control arithmetic unit configured by, for example, mounting at least one processor (CPU) and at least one memory (SRAM, DRAM, etc.) on an integrated circuit. The arithmetic processing unit  49  outputs information on a position and a direction of the eyewear device  4  detected by the relative position sensor  45  and the relative direction sensor  46  to the data management device  6 . In addition, the arithmetic processing unit  49  synchronizes a coordinate system of assistance display data received from the data management device  6  with the eyewear device  4  and displays the data on the display  41 . 
     4. Data Management Device  6   
       FIG.  6    is a configuration block diagram of the data management device  6  according to the present embodiment. The data management device  6  is an information processing device, and is typically a personal computer, a server computer, etc., or may be a tablet terminal, a smartphone, etc. In the illustrated example, the data management device  6  is a laptop computer. The data management device  6  may be one computer or a computer system in which a plurality of computers dispersively perform processing, or may logically use a part of processing resources of one or more computers. The data management device  6  may be configured as a portion of the eyewear device  4 , or may be configured as a portion of the surveying instrument  2 . A part of processing of the data management device  6  may be performed by the eyewear device  4 , and a part of the processing may be performed by the surveying instrument  2 . 
     The data management device  6  includes at least a communication unit  61 , a display unit  62 , an operation unit  63 , a control arithmetic unit  64 , and a storage unit  65 . 
     The communication unit  61  is a communication control device such as a network adapter, a network interface card, a LAN card, or a Bluetooth (registered trademark) adapter, and enables the data management device  6  to communicate with the surveying instrument  2  and the eyewear device  4  by wire or wirelessly. The control arithmetic unit  64  can transmit and receive information to and from the surveying instrument  2  and the eyewear device  4  through the communication unit  61 . The data management device  6  may be installed in a local environment to make communication with the surveying instrument  2  and the eyewear device  4 , and may be realized as a so-called cloud environment to make communication with the surveying instrument  2  and the eyewear device  4  through a communication means such as the Internet. 
     The display unit  62  is, for example, a liquid crystal display. The operation unit  63  is, for example, a keyboard, a mouse, etc., and can input various instructions, selections, and determinations, etc., by a worker. 
     The control arithmetic unit  64  is a control arithmetic unit including, for example, at least one processor (for example, CPU) and at least one memory (DRAM, SRAM, etc.). By reading out data and programs stored in the storage unit  65  into the memory and executing the programs by the processor, functions of the functional units can be executed. At least a part of the control arithmetic unit  64  may be mounted by using a dedicated circuit. 
     The control arithmetic unit  64  includes, as functional units, a synchronous-measuring unit  641 , a survey process data reading unit  642 , a work assistance image creating unit  643 , and a work assistance image display unit  644 . 
     The synchronous-measuring unit  641  receives information on a position and a direction of the surveying instrument  2  and information on a position and a direction of the eyewear device  4 , converts a coordinate space of the surveying instrument  2  and a coordinate space of three-dimensional position information created in the absolute coordinate system so that these coordinate spaces match a coordinate space of the eyewear device  4  which has an origin set at a common reference point, and transmits the information to the eyewear device  4 . Accordingly, the information acquired by the surveying instrument  2  and the three-dimensional position information created in the absolute coordinate system can be managed in the same coordinate space as the coordinate space of the eyewear device  4 . 
     In the present description, “synchronization” means, as described above, matching coordinate spaces of information on positions and directions in devices or design data with different coordinate spaces, and managing relative positions and relative directions related to the respective devices in a common coordinate space with an origin set at a common reference point. 
     The survey process data reading unit  642  reads out survey process data  91  stored in the storage unit  65 .  FIG.  7 A  illustrates an example of the survey process data  91 , and  FIG.  7 B  is a diagram schematically illustrating the survey process data  91  illustrated in  FIG.  7 A  as a plan view of a survey site for understanding. 
     The survey process data  91  is data corresponding to a process chart and a working drawing in the surveying work in question. The working drawing generally means a drawing necessary for performing a work at a site of construction, however, here, it means a drawing obtained by adding information necessary for performing a surveying work to a design drawing. The working drawing is created based on a design drawing of the survey site created based on three-dimensional CAD data in the absolute coordinate system. Therefore, information related to positions in the survey process data  91  included in the working drawing is position information in the absolute coordinate system. 
     The survey process data  91  includes at least three-dimensional position information of instrument installation points in the absolute coordinate system, type information of a surveying instrument to be used, and a measurement order of the instrument installation points. As illustrated in  FIG.  7 A , the type information of a surveying instrument to be used may include a type code and a model number. Here, the model number is a number assigned by a manufacturer according to functions and a version. In addition, the survey process data  91  may include type and model number information of accessory (for example, a tripod, etc.) to be used together with the surveying instrument in addition to the surveying instrument. The survey process data  91  may include a design drawing of a survey site. The survey process data may include information on a measurement point as a measuring object, and information on a measurement range of a scanner when the surveying instrument is the scanner. Information on a measurement point and information on a measurement range of a scanner are information related to positions. 
     Those included in the survey process data  91  can be determined as appropriate such as items expected to be displayed as a work assistance image  93  (hereinafter, also simply referred to as “work assistance image”). In the present description, the surveying instrument includes various kinds of surveying instruments to be used for surveying works. Specifically, the surveying instrument includes total stations, three-dimensional scanners, electronic levels, theodolites, and GNSS devices, etc. 
     In the survey process data  91 , information related to positions of instrument installation points P1, P2 . . . (hereinafter, referred to as instrument installation points P unless they are distinguished), a measurement point Q1 and measurement areas A, B, C . . . includes three-dimensional position information in the absolute coordinate system.  FIG.  7 B  illustrates information in a plan view, however, information related to positions are included as three-dimensional position information in the absolute coordinate system as described above, so that the survey process data  91  is created as three-dimensional data. The survey process data  91  is created in advance according to a plan of the survey in question. 
     Concerning work processes at instrument points in the survey process data  91 , the work assistance image creating unit  643  creates a work assistance image reflecting three-dimensional position information of the instrument points, etc., and a surveying instrument to be used by using work assistance data  92  stored in the storage unit  65 . 
     The work assistance data  92  is, for example, as illustrated in  FIG.  8   , a database arranged by linking appearance images of various surveying instruments to type information. An appearance image of a surveying instrument is taken by using at least two cameras so as to create three-dimensional data having actual dimensions through a photo survey method. 
     The work assistance image creating unit  643  creates a work assistance image  93  as three-dimensional data synchronized with the eyewear device  4  based on an appearance image of a surveying instrument obtained as three-dimensional data on the assumption that the surveying instrument is installed at the instrument installation point P. 
     The work assistance image  93  is an image reflecting three-dimensional position information of the instrument installation points, etc., and a surveying instrument to be used. Specifically, for example, when an instrument to be used at the instrument installation point P2 is a scanner S 07 , the work assistance image is displayed as an image to indicate a state where the scanner S 07  is installed on the instrument installation point P2. 
     The work assistance image display unit  644  transmits the work assistance image  93  created by the work assistance image creating unit  643  to the eyewear device  4 , and displays it on the display  41 . 
     The storage unit  65  is, for example, an HDD or SSD (Solid State Drive). In the storage unit  65 , the above-described survey process data  91  and work assistance data  92  are stored. In addition, in the storage unit  65 , in the case where the respective functional units of the control arithmetic unit  60  are realized as software, programs for executing respective functions are stored. 
     5. Survey Assistance Method 
       FIG.  9    is a flowchart illustrating an example of processing of the control arithmetic unit in a survey assistance method using the survey assistance system  100 . In the survey assistance method using the survey assistance system  100 , first, as initial settings, Steps S 01  to S 03  are executed.  FIG.  10    is a work image view of Steps S 01  to S 03 . 
     First, in Step S 01 , a worker sets a reference point and a reference direction at an observation site. Specifically, a known point and an arbitrary point in the site are selected, and a position of the eyewear device  4  in a state where the worker stands while wearing the eyewear device is set as the reference point. In the site, a characteristic point (for example, a corner of a structural object, etc.) different from the reference point is arbitrarily selected, and a direction from the reference point to the characteristic point is set as a reference direction. 
     The processing shifts to Step S 02 , and the worker synchronizes the surveying instrument  2 . Specifically, the worker installs the surveying instrument  2  at an arbitrary point in the site, and by a known method such as backward intersection method including the reference point and the characteristic point, grasps absolute coordinates of the surveying instrument  2 , and grasps absolute coordinates of the reference point and the characteristic point selected in Step S 101 . The surveying instrument  2  transmits the acquired absolute coordinates of the surveying instrument  2 , the reference point, and the characteristic point to the data management device  6 . 
     Next, the processing shifts to Step S 03 , and the worker synchronizes the eyewear device  4 . Specifically, the worker installs the eyewear device  4  at the reference point, matches a center of the display  41  with the reference direction, and sets (x, y, z) of the relative position sensor  45  to (0, 0, 0) and sets (roll, pitch, yaw) of the relative direction sensor  46  to (0, 0, 0). After that, with respect to information from the eyewear device  4 , the synchronous-measuring unit  641  of the data management device  6  manages a relative position and a relative direction of the eyewear device  4  in a space with an origin set at the reference point. For synchronization of the eyewear device  4 , it is also preferable that the eyewear device  4  is provided with a laser device for indicating a center and a directional axis of the eyewear device  4 , and the center and the directional axis are matched with the reference point and the reference direction by using a laser as a guide. 
     Through the work described above, the eyewear device  4  can manage image data having three-dimensional position information created in the same absolute coordinate system as the reference point in a space with an origin set at the reference point, and superimpose and display the image data on the site landscape in accordance with a position and a direction of a site landscape. 
     Next, in Step S 04 , for example, when the worker pushes the function button  48   b  corresponding to a function button displayed on the display  41  to start execution of survey assistance, in Step S 05 , the survey process data reading unit  642  reads out the survey process data  91  stored in the storage unit  65 . 
     Next, in Step S 06 , the work assistance image creating unit  643  creates a work assistance image by using the work assistance image data. 
     Next, in Step S 07 , the work assistance image display unit  644  transmits the work assistance image created by the work assistance image creating unit  643  to the eyewear device  4 , and displays the work assistance image on the display  41 . The display is updated according to changes in direction and position of the eyewear device  4 . 
     Next, in Step S 08 , when an instruction to end is input by the operation switch, the processing is ended. 
       FIGS.  11 A,  11 B,  11 C, and  11 D  are diagrams illustrating examples of the work assistance image. In the figures, portions indicated by dashed lines represent a site landscape, and portions indicated by solid lines represent the work assistance image  93  created by the work assistance image creating unit  643 . As illustrated in  FIG.  11 A , the eyewear device  4  displays, as the work assistance image  93 , instrument installation points P, images of a surveying instrument installed at the instrument installation points P, and information on the surveying instrument such as a type and a model number, etc., of the surveying instrument, superimposed on the site landscape. An accessory of the surveying instrument may also be displayed in the same manner. The images of the surveying instrument have actual dimensions in the absolute coordinate system, and on the display  41 , these images are enlarged or scaled down according to distances from the eyewear device  4 . 
     In this way, in the present embodiment, as the work assistance image  93 , at least the instrument installation points P and images of the surveying instrument to be used installed at the instrument installation points P are superimposed and displayed on a site landscape, so that a worker can easily recognize positions of the instrument installation points P and a surveying instrument to be installed on the instrument installation points P. In particular, the surveying instrument is displayed by using a photo image. Therefore, it can be identified according to its color and shape, etc. Accordingly, without special attention, the worker can select an instrument to be installed among instruments that the worker brought. In addition, information on the type and model number, etc., is displayed in parallel, so that the information can be confirmed as necessary. 
     As illustrated in  FIGS.  11 A to  11 C , the work assistance image  93  is switchable among a display mode (display mode 1:  FIG.  11 A ) in which the whole of the work assistance image  93  is displayed, a partial display mode (display mode 2:  FIG.  11 B ) in which only instrument points in the work assistance image  93  are displayed, and a non-display mode (non-display mode:  FIG.  11 C ) in which the work assistance image  93  is not displayed. 
     In the illustrated example, by pressing the function button  48   b  corresponding to a display  94  of a mode changeover button, the mode can be switched in order. 
     In addition, in the work assistance image  93 , instead of simultaneous display of the images of the instrument at all instrument installation points, the display may be updated so that the images of the instrument at the instrument installation points P are displayed one by one in order according to the process, and then, each time a work at an instrument installation point is completed, by pressing the function button  48   b  corresponding to a display  95  of a “Next” button illustrated in  FIG.  11 D , an instrument at the next instrument installation point P is displayed. At this time, a gauge  96  indicating current progress relative to the entire process may be displayed on the display  41 . 
     According to the configuration described above, a worker can confirm an instrument necessary for the next work without confirming the process chart again. In addition, just by following a guidance on the display, the worker can execute a work as planned in the process chart. In particular, by displaying a gauge indicating progress of the process, the worker can easily grasp the progress of the entire process. 
     6. Modification 1 
       FIG.  12    illustrates work assistance data  92 A of a survey assistance system  100 A according to Modification  1 . Although not illustrated in the figure, the hardware configuration of the system  100 A is similar to that of the system  100  illustrated in  FIG.  6   . In the system  100 A, the storage unit  65  includes the work assistance data  92 A instead of the work assistance data  92 . The work assistance data  92 A includes, in addition to content of the work assistance data  92 , information on precautions for measurement according to the type of the instrument. Specifically, information on a precaution according to characteristics of the type is included in a manner such that, when the total station TS 01 XYX1 is a device required high measurement accuracy, information on precautions such as “Measure in state with less fog (visibility: approximately 20 km), an appropriate amount of sunshine, and no heat haze” is included. When the total station TS04 YYX3 is a device using a radio, information on precautions such as “Measure in state with no obstacles, no radio disturbance in the vicinity, and no influences from noise” is included. Information on precautions may include other various cautions for measurement. 
     When performing the survey assistance method, as illustrated in  FIG.  13   , the work assistance image creating unit displays a precaution  98  for measurement according to the type of the instrument on a work assistance image  93 A in addition to the type information. For example, as illustrated in  FIG.  13   , the type information “S07 XZ21” and precaution information “Measure in state with less fog (visibility: approximately 40 km), cloudy, and no heat haze” are displayed. The worker confirms whether the current conditions meet the conditions prescribed in the precaution, and when the conditions are not met, takes a measure such as waiting until the start of the measurement conditions are met. 
     An experienced worker has acquired such precautions as rules of thumb, however, it is difficult for an inexperienced worker to memorize these for all of various kinds of surveying instruments. The above-described configuration enables even an inexperienced worker to perform a surveying work while paying attention to appropriate precautions. 
     7. Modification 2 
       FIG.  14    illustrates work assistance data  92 B of a survey assistance system  100 B according to Modification 2. A hardware configuration of the system  100 B is similar to that of the system  100 , however, the work assistance data  92 B includes, for each detailed process at each instrument installation point, an image of a surveying instrument describing work content of the process. As in the work assistance data  92  in the system  100 , an image of a surveying instrument describing work content is created as three-dimensional data. The image describing work content may be a still image or a moving image. 
     A work assistance image creating unit  643 B (not illustrated) creates, as an image of a surveying instrument describing work content, three-dimensional data not of an image showing a state where the surveying instrument is installed at the instrument installation point P, but of an image describing work content in a state where the surveying instrument is installed at a position offset a predetermined distance from the instrument installation point P. 
       FIG.  15    illustrates an example of the work assistance image  93 B created based on the work assistance data  92 B. As the work assistance image  93 B, an image describing work content (here, describing a work to set a bubble of a bubble tube at a center by rotating a leveling screw for leveling) is displayed next to an actual surveying instrument in the same visual field. 
     According to the configuration described above, a worker can perform a work while viewing the work assistance image  93 B displayed next to an actual surveying instrument. In the same visual field range, the worker can confirm an image describing work content with his/her hands free, so that even an inexperienced worker can perform the work without stress. 
     The work assistance data  92 B and the work assistance image creating unit  643 B (not illustrated), and the work assistance data  92  and the work assistance image creating unit  643 , are not alternatives, but both of these may be provided. 
     II. Second Embodiment 
     1. Observation Route Calculation Method 
     Before describing a survey assistance system  200  according to a second embodiment, positions and a measurement order of instrument installation points included in the survey process data  91  will be described. In the first embodiment, the description is simply given that positions and a measurement order of instrument installation points are planned in advance. 
     In the case of point cloud observation using a scanner, positions and a measurement order of the instrument installation points need to be set so that measurement ranges from the respective instrument installation points overlap each other to achieve a desired point cloud density. For convenience, a route unicursally connecting such instrument installation points in order of measurement is referred to as an observation route  97 . 
     It is considered that such an observation route can be calculated by an information processing device such as a personal computer based on instrument information of the scanner (coordinates of instrument center, pulse interval setting, and scanning rotation speed setting) and three-dimensional CAD design data of a survey site. 
       FIG.  16    is a view three-dimensionally illustrating an image of a point cloud data acquirable region K of the scanner.  FIGS.  17 A,  17 B, and  17 C  are plan views schematically illustrating instrument installation point settings for calculation of an observation route.  FIG.  18 A  illustrates an example of a calculated observation route  97 , and  FIG.  18 B  illustrates an example of display of the observation route  97  on the display  41 . 
     In the present embodiment, the scanner is a three-dimensional laser scanner which further includes a turning mirror that causes distance-measuring light to scan 360° in the vertical direction in the vertical rotation driving unit of the three-dimensional coordinate measuring unit  21  of the surveying instrument  2 , and capable of acquiring three-dimensional point cloud data of the periphery by performing scanning with distance-measuring light in the vertical direction and the horizontal direction. 
     Therefore, as illustrated in  FIG.  16   , the point cloud data acquirable region K is a substantially semispherical region A centered at an instrument center C of the scanner. For convenience of drawing, the instrument center C is illustrated as being on the ground, however, in actuality, the instrument center C is positioned higher by an instrument height of the scanner than the ground. 
     A density of points to be acquired by the scanner becomes higher as the pulse interval of the distance-measuring light becomes narrower, and becomes lower as the scanner rotation speed becomes higher, and becomes lower with increasing distance from the instrument center of the scanner. In this way, the point cloud density depends on pulse interval setting of the distance-measuring light of the scanner, rotation speed setting of the scanner, and the distance from the instrument center of the scanner. 
     In point cloud data observation, a required point cloud density is set according to the purpose of observation and a request from a client. A scanner observation range includes a region K 1  in which the required point cloud density can be satisfied by one measurement, and a region K 2  in which the required point cloud density cannot be satisfied by one measurement, but can be satisfied by overlapping with measurement from other points. Therefore, to design the observation route  97 , for example, as illustrated in  FIG.  17 A , the instrument installation points P need to be set so as to satisfy the required point cloud density in the entire observation site. 
     However, the point cloud data observation is a survey for acquiring three-dimensional data of three-dimensional structural objects at an observation site, so that at an observation site, three-dimensional structural objects (for example, three-dimensional structural objects S 1 , S 2 , and S 3  in  FIGS.  17 A,  17 B, and  17 C ) are present. When three-dimensional structural objects are present, for example, as illustrated in  FIG.  17 B , when the three-dimensional structural object S 1  is irradiated with (reflects) distance-measuring light from the scanner installed at the instrument installation point P, the distance-measuring light does not reach a portion B at an opposite side of the scanner with respect to the three-dimensional structural object, and point cloud data cannot be acquired. The same occurs three-dimensionally. 
     Therefore, by performing a computer simulation in consideration of the pulse interval setting of the distance-measuring light of the scanner, the rotation speed setting of the scanner, the distance from the instrument center of the scanner, and positional relationships with the three-dimensional structural objects by using the three-dimensional CAD design data of the survey site, as illustrated in  FIG.  17 C , positions of least instrument installation points that can cover the entire observation range at the required point cloud density are calculated. That is, point cloud data acquirable regions are calculated by excluding portions B at opposite sides of the scanner with respect to three-dimensional structural objects from the point cloud data acquirable regions K of the scanner, and by overlapping these calculated point cloud data acquirable regions, positions of least instrument installation points P that cover the entire observation site are obtained while the required point cloud density is achieved. 
     Further, a shortest route unicursally connecting the calculated instrument installation points P is calculated as illustrated in  FIG.  18 A . Accordingly, a shortest observation route  97  connecting the instrument installation points arranged so as to cover the entire observation site at the required point cloud density is calculated. 
     2. Survey Assistance System  200   
     The survey assistance system  200  includes an eyewear device  204  and a data management device  206  instead of the eyewear device  4  and the data management device  6  of the system  100 .  FIG.  19    is a configuration block diagram of the eyewear device  204  and the data management device  206  constituting the system  200 . 
     3. Eyewear Device  204   
     The eyewear device  204  includes a camera  42  in addition to the eyewear device  4 . 
     The camera  42  includes an image sensor, for example, a CCD, CMOS, etc., and takes a front landscape image of the eyewear device  4  in real time. The image sensor has an orthogonal coordinate system with an origin set at a camera center, and local coordinates of each pixel are identified. A positional relationship between the camera center and a center of the eyewear device  4  is known, and the eyewear device  4  can convert a coordinate space of an image acquired by the camera  42  into a coordinate space of the eyewear device  4  and manage the image. When the display  41  is a video see-through type and the eyewear device  4  includes a camera, the camera may be provided as a common camera. 
     4. Data Management Device  206   
     The data management device  206  includes, in addition to the data management device  6 , in a control arithmetic unit  264 , an image acquiring unit  645 , a three-dimensional converting unit  646 , a difference calculating unit  647 , and an observation route recalculating unit  648 , and includes a work assistance image creating unit  643 A instead of the work assistance image creating unit  643 . 
     The image acquiring unit  645  acquires a plurality of landscape images of the site taken by the camera  42 . The landscape images are acquired so that at least the entire survey site is imaged from two or more different points in the survey site. 
     The three-dimensional converting unit  646  converts the plurality of landscape images acquired by the image acquiring unit  645  into three-dimensional data in the absolute coordinate system by using a photo survey method. Three-dimensional data of the survey site obtained from the acquired images is referred to as site three-dimensional data. 
     The difference calculating unit  647  calculates a difference between the site three-dimensional data and CAD design data included in the survey process data  91 . 
     The observation route recalculating unit  648  recalculates the observation route  97  when there is a difference between the site three-dimensional data and the CAD design data (when a difference between them is more than a predetermined threshold). 
     A recalculated route reflecting unit  649  creates work assistance data  692  by reflecting the recalculated observation route  97  (instrument installation points and a measurement order) in the work assistance data  92 . 
     The work assistance image creating unit  643 A creates a work assistance image based on the work assistance data  692  in which the recalculation is reflected. 
       FIG.  20    is a flowchart of processing of the control arithmetic unit  60  in a survey assistance method using the survey assistance system  200 . 
     In Steps S 101  to S 103 , as in Steps S 01  to S 03 , the surveying instrument  2  and the eyewear device  204  are synchronized. 
     When survey assistance starts in Step S 104 , the survey process data reading unit  642  reads out the survey process data  91  in Step S 105 . 
     In Step S 106 , a worker takes photos of the entire landscape of the survey site from at least two or more points by using the camera  42 . The image acquiring unit  645  acquires a plurality of landscape images. 
     Next, in Step S 107 , the three-dimensional converting unit  646  converts the plurality of landscape images acquired by the image acquiring unit  645  into site three-dimensional data in the absolute coordinate system by a photo survey method. 
     Next, in Step S 108 , the difference calculating unit  647  calculates a difference between the site three-dimensional data and CAD design data included in the survey process data  91 . 
     Next, in Step S 109 , the observation route recalculating unit  648  recalculates the observation route  97  when there is a difference between the site three-dimensional data and the CAD design data (when a difference between them is more than a predetermined threshold). 
     Next, in Step S 110 , the recalculated route reflecting unit  649  creates the work assistance data  692  by reflecting the recalculated observation route  97  (instrument installation points and a measurement order) in the work assistance data  92 . 
     Subsequently, in Step S 111 , the work assistance image creating unit  643 A creates a work assistance image based on the work assistance data  692  in which the recalculation is reflected. The subsequent processing is the same as Steps S 07  and S 08 . 
     According to the configuration described above, even when there is a difference between a working drawing based on a CAD design drawing and CAD design data, and an actual site, after reflecting the difference in the survey process data  91 , the survey assistance method can be performed, so that a plan change at the site can be quickly reflected. 
     Preferred embodiments of the present invention have been described above, and the embodiments described above are just examples of the present invention, and can be combined based on the knowledge of a person skilled in the art, and such a combined embodiment is also included in the scope of the present invention. 
     REFERENCE SIGNS LIST 
       2 : Surveying instrument
   4 ,  204 : Eyewear display device
   21 : Three-dimensional coordinate measuring unit
   26 : Communication unit
 
       41 : Display 
       42 : Camera 
       44 : Communication unit
   45 : Relative position detection sensor
   46 : Relative direction detection sensor
   61 : Communication unit
   64 ,  264 : Control arithmetic unit
   91 : Survey process data
   93 ,  93 A,  93 B: Work assistance image
 
       96 : Gauge 
       100 ,  100 A,  100 B,  200 : Survey assistance system
   641 : Synchronous-measuring unit
   642 : Survey process data reading unit
   643 ,  643 A,  643 B: Work assistance image creating unit
   644 : Work assistance image display unit