Patent Publication Number: US-2023152095-A1

Title: Surveying method, surveying system, and recording medium storing surveying program

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority from Japanese Patent Application No. 2021-186003, filed Nov. 15, 2021; the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a surveying method, a surveying system, and a recording medium storing a surveying program. 
     “Batter boards” are set to determine the positions of columns and walls before the start of construction. Batter boards are temporary frameworks prepared by placing stakes and beams at necessary points prior to foundation construction in order to set the horizontal lines or other indicators of the foundations of concrete or other buildings. After setting up the batter boards, for example, marking of foundation points based on design information is performed, in foundation construction of a building. For example, Japanese Patent No. 3784763 discloses such a technique that light emitters are placed at candidate points assumed to be true marking points, light emitted from the light emitters at the candidate points is detected using transits, and deviations between detected values of the candidate points and values of the marking point are calculated out as a difference in latitude and longitude. 
     SUMMARY 
     It is required that a building be constructed with a margin of a predetermined distance from a land boundary. Sometimes an actual land boundary at a construction site would be inconsistent with, for example, design information obtained in advance by a contractor, so that the distance between the building and the boundary would be different from the design information. There would thus be a case that requires checking whether the positional relationship (e.g., the distance) between the marking point and the boundary is appropriate at the stage of foundation construction. For example, according to Japanese Patent No. 3784763 described above, a light emitter placed at a point assumed as a marking point to be surveyed is detected by transits with reference to two benchmarks on boundary lines. However, obtaining the relative positional relationship between a reference line drawn by connecting marking points and a boundary line is not easy. 
     One aspect of the present disclosure was achieved in view of the above. It is an object of the present disclosure to provide a surveying method, a surveying system, and a recording medium storing a surveying program that allow an operator to efficiently acquire a position at a site. 
     In order to achieve the object, a surveying method according to the present disclosure uses a surveying system including a surveying device and a terminal, the surveying method including: receiving, by the terminal, a result of selecting a survey target foundation point from among a plurality of consecutive foundation points; obtaining an intersection between a reference line and a boundary side set in advance, the reference line connecting the survey target foundation point and an adjacent foundation point adjacent to the survey target foundation point; and outputting, in association with the survey target foundation point, a relative positional relationship between the intersection and a survey target device surveyed by the surveying device for the survey target foundation point. 
     In order to achieve the object, a surveying system according to the present disclosure includes a surveying device and a terminal, the terminal including: an input unit configured to receive a result of selecting a survey target foundation point from among a plurality of consecutive foundation points; a control unit configured to obtain an intersection between a reference line and a boundary side set in advance, the reference line connecting the survey target foundation point and an adjacent foundation point adjacent to the survey target foundation point; and outputting, in association with the survey target foundation point, a relative positional relationship between the intersection and a survey target device surveyed by the surveying device for the survey target foundation point. 
     In order to achieve the object, a recording medium storing a surveying program according to the present disclosure is a recording medium storing a surveying program using a surveying system including a surveying device and a terminal, the surveying program causing a computer to execute: receiving, by the terminal, a result of selecting a survey target foundation point from among a plurality of consecutive foundation points using the terminal; obtaining an intersection between a reference line and a boundary side set in advance, the reference line connecting the survey target foundation point and an adjacent foundation point adjacent to the survey target foundation point; and outputting, in association with the survey target foundation point, a relative positional relationship between the intersection and a survey target device surveyed by the surveying device for the survey target foundation point. 
     The surveying method, the surveying system, and the recording medium storing the surveying program according to the present disclosure allow an operator to efficiently acquire a position at a site. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates an example construction site with batter boards. 
         FIG.  2    is a configuration diagram of a surveying system according to an embodiment of the present disclosure. 
         FIG.  3    is a configuration diagram of design information. 
         FIG.  4    is a configuration diagram of surveying information. 
         FIG.  5    is a flowchart showing a process of measuring a relative position of a foundation point. 
         FIG.  6    shows an example screen for measuring the relative position of the foundation point. 
         FIG.  7    illustrates the relationship between a batter board stake and the altitude of a benchmark. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present disclosure will be described below with reference to the drawings.  FIG.  1    illustrates an example construction site with batter boards  3 . “Batter boards” are for determining the positions of columns and walls before the start of construction and are temporary frameworks prepared by placing stakes and beams at necessary points prior to foundation construction in order to set the horizontal lines or other indicators for the foundations of buildings, which are made from concrete or the like. A series of operations using the batter boards  3  is also referred to as “setting batter boards”. The batter boards  3  become unnecessary after setting marks, such as reference marks, on an immovable object as a reference, and are eventually removed. For example, the batter boards  3  are corner batter boards arranged in a substantially L-shape in a plan view. For example, a batter board  3  at a foundation point MPH 2  in  FIG.  1    includes batter board stakes  31 A,  31 B, and  31 C (collectively  31 ) and batter board beams  32  and  32 A and  32 B (collectively  32 ). Such corner batter boards are placed at four corners of a building, in the case where the building is rectangular. Across the facing corner batter boards, leveling strings (not shown) are stretched out. In the present disclosure, the batter board stakes  31 A to  31 C have the same functions and are collectively referred to as the “batter board stakes  31 ” without distinction. Similarly, the batter board beams  32  and  32 A to  32 D are also collectively referred to as “batter board beams  32  and  32 .” 
     The batter board stakes  31  are stakes driven into the ground for setting a batter board  3 , and may be referred to as Mizukui or Kentokui in Japanese. Each batter board stake  31  is provided with a mark LM drawn thereon, the mark LM indicating the position of a beam top  321  (the upper end of a batter board beam  32 ). This mark LM is also referred to as a “horizontal mark.” The mark LM indicates the altitude of the foundation of the building. The batter board beam  32  is a horizontal plate, which is placed with its upper end aligned with the mark LM on the batter board stake  31  so as to indicate the altitude of the foundation. 
     Inside the batter boards  3 , the leveling strings (not shown) are horizontally stretched across the batter board beams  32  and  32  facing with each other, so that the leveling strings are provided along reference lines ML 11  and ML 12  (collectively ML 10 ). The reference line ML 11  includes a reference side ML 1  and an extension (e.g., an imaginary extension VL 1 ) of the reference side ML 1 , while the reference line ML 12  includes a reference side ML 2  and an extension (e.g., an imaginary extension VL 2 ) of the reference side ML 2 . The leveling strings may be nylon or polyethylene strings or piano wires. The leveling strings indicate a height which is the altitude of the building foundation. Reference sides ML 1  to ML 4  shown in  FIG.  1    are imaginary lines indicating the positions at which the leveling strings need to stretch as design information  121  set in advance. The reference sides ML 1  to ML 4  are worked out to connect foundation points MPH 1  to MPH 4  (see also  FIG.  6   ) given as the design information  121 . These foundation points MPH 1  to MPH 4  can be start points or end points of the reference sides ML 1  to ML 4 . 
     The leveling strings are stretched out across the facing batter board beams  32  and  32  by being fixed to fixing points on the batter board beams  32  and  32  by nailing or any other suitable means. For example, a leveling string is stretched out between the batter board beam  32 A and the batter board beam  32 D facing thereto. The leveling strings stretched substantially horizontally are at substantially the same height as the marks LM. 
       FIG.  2    is a configuration diagram of a surveying system  1  according to the embodiment of the present disclosure. The surveying system  1  includes a surveying device  200 , a terminal  100 , and a survey target device  300 . 
     The surveying device  200  is a surveying instrument of a total station (TS)-equivalent light wave type on known coordinates, for example. Examples of the “TS-equivalent light wave type” include, in addition to the TS, non-telescopic light wave-based measurement instruments capable of performing measurement equivalent to that is performed by the TS equipped with an automatic tracking function. The surveying device  200  can automatically track the survey target device  300  as a survey target, so that, by tracking the survey target device  300 , the surveying device  200  can survey a desired point at a construction site at which the survey target device  300  is placed. The survey target device  300  includes an optical element that reflects light radiated from the surveying device  200  back to the surveying device  200 . This optical element is what is called a “retroreflective prism”  301  (see also  FIG.  7   ) with retroreflective properties. The survey target device  300  may be a surveying pole, which is a pole  302  with a known length and with the retroreflective prism  301  provided thereon. 
     The surveying device  200  includes a horizontal rotation driving unit and a telescope unit on the horizontal rotation driving unit with a vertical rotation driving unit interposed therebetween. The horizontal rotation driving unit is supported by a tripod and drives horizontal rotation. The vertical rotation drive unit is vertically rotatable. The surveying device  200  includes an angle measurement unit  212   a  including horizontal angle detector and a vertical angle detector (the details are not shown). The horizontal angle detector detects the horizontal rotation angle, whereas the vertical angle detector detects the vertical rotation angle. With these horizontal and vertical angle detectors, the surveying device  200  can measure the horizontal and vertical angles of the collimation direction, respectively. 
     The surveying device  200  further includes a distance measurement unit  211  that measures a slope distance to the survey target device  300 . The distance measurement unit  211  may be an electro-optical distance meter, for example. For the sake of convenience, these angle and distance measurement units  212  and  211  are collectively referred to as a “surveying unit  210 .” 
     The surveying device  200  includes the surveying unit  210 , a surveying storage unit  220 , a surveying communication unit  230 , a surveying control unit  240 , and a tracking control unit  250 . 
     The surveying storage unit  220  stores, in advance, various programs for the surveying, tracking, or other controls; or information (e.g., the altitude) on the ground, design information  121 , or other information, which are used at a construction site or the like. The surveying storage unit  220  also stores surveying information  122 . The surveying device  200  includes a computer for executing programs. 
     The surveying communication unit  230  has a function capable of communicating with external devices, such as the terminal  100 , and may be any suitable wireless or wired communication means, for example. 
     The surveying control unit  240  controls the functions, such as surveying, of the surveying device  200 . More specifically, the surveying control unit  240  automatically or manually collimates the survey target device  300 . The surveying control unit  240  detects the horizontal angle, the vertical angle, and the slope distance between the surveying device  200  and the survey target device  300  using the angle measurement unit (i.e., the horizontal and vertical angle detectors)  212  and the distance measurement unit  211  described above. If the survey target device  300  is a surveying pole including a pole  320  and a retroreflective prism  301 , the distance from the retroreflective prism  310  to the distal end (i.e., upper or lower end) of the pole  320  is known in advance. Accordingly, the surveying control unit  240  can correct the surveyed position of the retroreflective prism  301  determined by the angle measurement unit  212  and the distance measurement unit  211  to calculate out the position of the distal end (i.e., upper or lower end) of the pole  320  as a result of surveying. 
     The tracking control unit  250  controls a tracking unit including a light source and is configured to control the drive of the horizontal and vertical rotation driving units in such a way that tracking light emitted from the tracking unit and then reflected from the survey target device  300  is continuously received by the tracking unit, thereby causing the surveying device (telescope unit)  200  to track the survey target device  300 . 
     The terminal (terminal device)  100  may be, for example, a smartphone, a feature phone, a tablet, a handheld computer device (e.g., a personal digital assistant (PDA)), a wearable terminal (e.g., a glasses-type device, a watch-type device), or any other suitable device. As an alternative, the terminal  100  can be implemented by installing application software in a general-purpose device. The terminal  100  may be, for example, a portable terminal easily carriable at a work site. Therefore, it is easy for an operator to view a display unit  150 , carrying the terminal  100  in a hands-free way or carrying the terminal  100  in one hand. 
     The terminal  100  includes a terminal control unit  110 , a terminal storage unit  120 , a terminal communication unit  130 , an input unit  140 , and the display unit  150 . 
     Although not shown, the terminal control unit  110  executes functions and/or methods implementable by codes or commands included in programs stored in the terminal storage unit  120 . The terminal  100  includes a computer for executing the programs. Examples of the terminal control unit  110  include a central processing unit (CPU), a microprocessor unit (MPU), a graphics processing unit (GPU), a microprocessor, a processor core, a multiprocessor, an application specific integrated circuit (ASIC), and a field-programmable gate array (FPGA), and the like. The terminal control unit  110  may include a logic circuit or a dedicated circuit formed in an integrated circuit, for example, to execute the processing disclosed in the embodiment. These circuits may be one or more integrated circuits. A single integrated circuit may execute plural steps of the processing described in the embodiment. The terminal control unit  110  may also include a main storage unit that temporarily stores therein a program read out from the terminal storage unit  120  and provides a workspace for the program. 
     The terminal communication unit  130  has a function capable of communicating with the surveying communication unit  230  of the surveying device  200 . The terminal communication unit  130  is capable of receiving, for example, a surveying result obtained by surveying the survey target device  300  by the surveying device  200  or positional information (a horizontal angle, a vertical angle, and a slope distance to the pole end) calculated by the surveying control unit  240 . The calculation of the positional information according to the surveying results may be performed by the surveying device  200  or by the terminal  100 . The communications between the surveying device  200  and the terminal  100  may be established by wire or wirelessly. Any communication protocol may be used to establish the communications between the surveying device  200  and the terminal  100 , as long as mutual communications can be established therebetween. 
     The input unit  140  may have any suitable configuration capable of receiving inputs from an operator  2  who is the user of the device  100  and transmitting information related to the inputs to the terminal control unit  110 . Examples of the input unit  140  include, in addition to a hardware input means such as buttons, a software input means displayed on the display unit  150 , such as a touch panel, a remote controller, or an audio input means such as a microphone. 
     The display unit  150  may have any suitable configuration capable of displaying images (screens). Examples of the display unit  150  include a flat display such as a liquid crystal display or an organic light-emitting diode (OLED) display, a curved display, a folding screen on a foldable terminal, a head-mounted display, and a device displayable through projection (including aerial projection) on an object using a small projector. 
     The terminal storage unit  120  has a function of storing various necessary programs (e.g., a surveying program, which will be described later) or various data. In addition, the terminal storage unit  120  can store therein the surveying information  122  received by the terminal communication unit  130  and the positional information calculated based on the surveying information  122 . The terminal storage unit  120  can store therein information (e.g., the altitude) on the ground for the construction etc., design information  121 , or any other suitable information. The terminal storage unit  120  may be a storage medium, such as a hard disk drive (HDD), a solid-state drive (SSD), or a flash memory. 
     The design information  121  includes design drawings necessary for construction works, for example. Examples of the construction works include constructions of structures such as buildings, roads, railroads, tunnels, bridges, ditches, waterways, and rivers. The terminal storage unit  120  according to this embodiment includes, as the design information  121 , data on a plurality of foundation points MPH 1  to MPH 4  and a plurality of boundary points DPK 1  to DPK 5  (here, the suffixes of MP and DP indicate identification information  121   a  and  122   a  on foundation points MP and the boundary points DP) in such a way that identification information  121   a , coordinate information  121   b , and other information are stored in association with each other (see  FIG.  3   ). 
       FIG.  3    is a configuration diagram of the design information  121 . The design information  121  includes the identification information  121   a  and the coordinate information  121   b  on the foundation points MP and/or the boundary points DP stored in association with each other. The identification information  121   a  includes foundation point identification information  121   a   1  associated with the foundation points MP and boundary point identification information  121   a   2  associated with the boundary points DP. In this embodiment, the foundation point identification information  121   a   1  and the boundary point identification information  121   a   2  are each composed of an alphabet and a number. For example, the numbers of the foundation point identification information  121   a   1  are assigned as serial numbers along reference sides ML. On the other hand, the numbers of the boundary point identification information  121   a   2  are also assigned as serial numbers along boundary sides DL. That is, identification numbers are assigned to the plurality of foundation points MP and boundary points DP in a sequential order. The design information  121  may include information other than the information illustrated in  FIG.  3   . 
       FIG.  4    is a configuration diagram of the surveying information  122 . The surveying information  122  includes the identification information  122   a  assigned to the results of surveying the foundation points MP or the boundary points DP, coordinate information  122   b , a deviation  122   c , and a distance  122   d  stored in association with each other. The identification information  122   a  includes foundation point identification information  122   a   1  associated with the foundation points MP and boundary point identification information  122   a   2  associated with the boundary points DP. The foundation point identification information  122   a   1  and the boundary point identification information  122   a   2  are set in association with the foundation point identification information  121   a   1  and the boundary point identification information  121   a   2  of the design information  121 . In this embodiment, a suffix “+STK” is added to the foundation point identification information  121   a   1  and the boundary point identification information  121   a   2 . With respect to the results of surveying, the identification numbers are assigned to the plurality of foundation points MP and boundary points DP in a sequential order. The surveying information  122  may also include information other than the information shown in  FIG.  4   . 
     The terminal storage unit  120  stores therein, as application software programs, an imaginary extension calculation section  123 , a boundary side calculation section  124 , an intersection calculation section  125 , a relative position calculation section  126 , a beam top position calculation section  127 , a leveling string guide section  128 , and other sections that fulfill various functions. 
     The imaginary extension calculation section  123  has a function of calculating an imaginary extension VL which is an extension of a reference side (i.e., a foundation reference side) ML indicating where a leveling string is to be stretched out. The boundary side calculation section  124  has a function of calculating the boundary sides (boundary reference sides) DL indicating the boundary lines of a site based on the boundary points DP. The intersection calculation section  125  has a function of calculating intersections (e.g., intersections CP 1  and CP 2 ) between the boundary sides DL and the imaginary extensions VL. The relative position calculation section  126  has a function of calculating a relative positional relationship between the surveyed position of the survey target device  300  and the intersection on the boundary side corresponding to the selected survey target foundation point, and a relative positional relationship between the surveyed position and the selected foundation point MP (survey target foundation point). 
     The beam top position calculation section  127  has a function of calculating a difference in height from the stake top  311  of a batter board stake  31  to a reference height of a foundation (i.e., the beam top  321 , which will be described later with reference to  FIG.  7   ) stored in advance and displaying the difference on the display unit  150 . The calculation is performed based on the reference height of the foundation, the altitude of a benchmark BM measured by the surveying device  200 , and the altitude of the stake top  311  of the batter board stake  31 . The leveling string guide section  128  has a function of causing the terminal  100  to display, at the time of stretching a leveling string, the distances between the coordinates of the survey target foundation point (e.g., the coordinate information  121   b  of the design information  121 ) and the surveyed position of the survey target device  300  corresponding to the survey target foundation point. 
     Relative Position Measurement Function 
     Now, an outline of a relative position measurement function will be described, which is one aspect of the surveying method, the surveying system, and the surveying program according to one embodiment of the present disclosure. 
     According to laws, the foundation of a building needs to be constructed at a certain distance from a boundary line of a site. It is thus preferable to check the distance from a foundation point MP through which a leveling string stretches to the site boundary line (e.g., a boundary side DL) before setting a batter board  3 , for example. However, it is not easy to measure the boundary-based distance, which is the distance to the site boundary line, while grasping the foundation point MP. A boundary side DL 1  shown in  FIG.  1    is a side connecting the boundary point DPK 1  and the boundary point DPK 2 . An off-site structure  4 , such as a wall, may be present outside the boundary side DL 1 . The relative positional relationship in interest to be found out here is, for example, the boundary-based distance between the foundation point MPH 2  and the boundary side DL 1  on the X-Y coordinate plane (i.e., the coordinates on the horizontal plane). In order to measure the distance, the surveying system  1  calculates out an imaginary extension VL passing through a survey target foundation point selected from among the foundation points MP, and calculates out an intersection CP between the imaginary extension VL and a boundary side DL. The display unit  150  of the terminal  100  displays, for example in real time, a relative distance between the survey target device  300  and an intersection CP 2  and a relative distance between the survey target device  300  and the foundation point MPH 2 . Accordingly, the operator can easily move the survey target device  300  toward the survey target foundation point, via checking the display unit  150 . 
     In the following, the steps of measuring the relative positional relationship between a reference side (specifically, a foundation point MP) and the survey target device  300  or the site boundary line will be described.  FIG.  5    is a flowchart illustrating the flow of processing in a surveying method and a surveying program using the surveying system  1  according to this embodiment.  FIG.  6    shows an example screen for measuring relative positions of foundation points. 
     First, in step S 101 , an operator places the surveying device  200  at a site, thereby setting the device point of the surveying device  200 . The surveying device  200  surveys boundary points DP (e.g., boundary points DPK 1  to DPK 5 ) on the land boundary. The surveying control unit  240  records the coordinates (i.e., the X-, Y-, and Z-coordinates) of the surveyed boundary points DP in the surveying storage unit  220  as the surveying information  122  in such a way that the boundary point identification information  122   a   2  is associated with the coordinate information  122   b . Thereafter, the surveying device  200  records the surveying information  122  in the terminal storage unit  120  of the terminal  100  via the surveying communication unit  230  and the terminal communication unit  130 . Therefore, the boundary sides DL 1  to DL 5  displayed on the display unit  150  in step S 102  are set in advance through surveying performed by the surveying device  200 . 
     In step S 102 , the terminal control unit  110  reads out the design information  121  and the surveying information  122  from the terminal storage unit  120 , and displays positional information including the foundation points MP and the boundary points DP on the display unit  150 . In  FIG.  6   , the foundation points MPH 1  to MPH 4  and the boundary points DPK 1 +STK to DPK 5 +STK surrounding the foundation points MPH 1  to MPH 4  are displayed. Here, the positional information on the foundation points MP and the boundary points DP are displayed with the icons and points represented by black circles. 
     In step S 103 , the operator selects one of the foundation points MPH 1  to MPH 4  displayed on the display unit  150 , using the input unit  140 . The terminal control unit  110  receives, as a survey target foundation point, the one (e.g., the foundation point MPH 2 ) selected from among the plurality of consecutive foundation points MPH 1  to MPH 4 . The survey target foundation point can be selected by the operator via an icon or a figure, which is visual information displayed on the display unit  150 . As internal processing, the terminal control unit  110  receives the input of an instruction via the input unit  140  as indicating that the piece of foundation point identification information  121   a   1  associated with the selected survey target foundation point is selected. 
     In step S 104 , the terminal control unit  110  determines, as an adjacent foundation point, a foundation point (e.g., the foundation point MPH 1  or MPH 3  adjacent to the foundation point MPH 2 ) that is of a piece of foundation point identification information  121   a   1  assigned prior to or subsequent to the foundation point identification information  121   a   1  of the selected survey target foundation point (e.g., the foundation point identification information  121   a   1  “H 2 ” on the selected foundation points MPH 2 ). 
     The terminal control unit  110  also determines reference lines ML 10  connecting the survey target foundation point and either one of the adjacent foundation points adjacent to the survey target foundation point. The reference line ML 10  includes first and second reference lines (reference lines ML 11  and ML 12 ). The reference line ML 11  connects a survey target foundation point (e.g., the foundation point MPH 2 ) and a first adjacent foundation point (e.g., the foundation point MPH 1 ) that is one of adjacent foundation points adjacent to this survey target foundation point. The reference line ML 12  connects the survey target foundation point and a second adjacent foundation point (e.g., the foundation point MPH 3 ) that is another one of the adjacent foundation points adjacent to this survey target foundation point. The reference lines ML 11  and ML 12  extend in two different directions. In addition, each of the reference lines ML 11  and ML 12  (collectively ML 10 ) includes a reference side ML 1  or ML 2  (collectively ML) on which a foundation or the like of a structure is to be constructed, and an imaginary extension VL 1  or VL 2  (collectively VL) which is the extension of the reference side ML 1  or ML 2 . 
     In step S 105 , the terminal control unit  110  obtains the intersection CP between a reference line ML 10  and a boundary side DL set in advance. The reference line ML 10  connects a survey target foundation point and an adjacent foundation point adjacent to the survey target foundation point. First, the terminal control unit  110  determines the boundary sides DL 1  to DL 5 , where the boundary sides DL 1  to DL 5  are formed by connecting, in a circulative order of the boundary point identification information  122   a   2 , a plurality of boundary points DPK 1 +STK, DPK 2 +STK, DPK 3 +STK, DPK 4 +STK, and DPK 5 +STK, connecting the boundary point DPK 5 +STK to the boundary point DPK 1 +STK, where the plurality of boundary points DPK 1 +STK to the boundary point DPK 5 +STK are assigned with the boundary point identification information  122   a   2  in a sequential order. That is, the boundary sides DL 1  to DL 5  are worked out based on the actually surveyed boundary points DPK 1 +STK to DPK 5 +STK. Moreover, the intersections between reference lines and reference sides include the intersection (i.e., the first intersection) CP 1  between the reference line (i.e., the first reference line) ML 11  and the boundary side DL 3  and the intersection (i.e., the second intersection) CP 2  between the reference line (i.e., the second reference line) ML 12  and the boundary side DL 1  in accordance with the direction of the reference line. The obtained intersections CP 1  and CP 2  are displayed on the display unit  150 . 
     In step S 105 , the display unit  150  may display reference sides ML formed, as surrounding lines, by sequentially connecting the foundation points MP. The foundation point MPH 1  corresponding to the start point of the connecting in the foundation point identification information  121   a   1 , via the reference side ML 4 , to the foundation point MPH 4  corresponding to the end point of the connecting in the foundation point identification information  121   a   1  (i.e., the foundation point MP with the largest of the serial numbers according to the foundation point identification information  121   a   1 ). The display unit  150  may display a boundary side DL sequentially connecting the foundation points MP as the surrounding lines. The terminal control unit  110  may or may not display the obtained boundary sides DL 1  to DL 5  on the display unit  150 . 
     In step S 106 , the terminal control unit  110  works out the position of the survey target foundation point. The survey target foundation point is worked out, for example, via surveying performed with the surveying device  200  surveying the survey target device  300 , which is actually held by the operator. 
     In step S 107 , the terminal control unit  110  calculates out the relative positional relationship between the intersection CP and the position of the survey target device  300  surveyed by the surveying device  200  for the survey target foundation point, and displays the relative positional relationship on the display unit  150 . The relative positional relationship includes a “distance” (also referred to as a “boundary-based distance” or “foundation-based distance”) from the intersection CP 1  to the position of the survey target device  300 . In addition, the relative positional relationship includes a “deviation” which is the position of the survey target device  300  away from each reference line ML 10 . For example, the terminal control unit  110  displays, on the display unit  150 , the distances from either the intersections CP 1  or CP 2  to the position of the survey target device  300  and the deviation, which is the position of the survey target device  300  with respect to the reference line. 
     The display unit  150  in  FIG.  6    shows “boundary line deviation” for the respective “boundary  1 ” and “boundary  2 ”. The “boundary line deviation” is a relative position with respect to a reference line substantially parallel to a boundary side. For example, “boundary  1 ” shows a deviation with respect to the reference line ML 11 , while “boundary  2 ” shows a deviation with respect to the reference line ML 12 . The deviation can be, for example, a vertical distance from a point in interest to the reference line ML 11  or ML 12 . The display unit  150  also displays “distance from boundary” including a distance to the “boundary  1 ” (e.g., the boundary side DL 1 ) and a distance to the “boundary  2 ” (e.g., the boundary side DL 2 ). Examples of the distance include, for example, a distance from a point in interest to the intersection CP 2  on the boundary side DL 1  and a distance from the point in interest to the intersection CP 1  on the boundary side DL 3 . 
     In step S 108 , once an operator selects a “RECORD” button  151  displayed on the display unit  150 , the terminal control unit  110  receives this record instruction and records, in the terminal storage unit  120 , the currently calculated and displayed deviation and distance information as the deviation  122   c  and a distance  122   d  according to the surveying information  122  (see  FIG.  4   ). The terminal control unit  110  also records, in the terminal storage unit  120 , the coordinate information on the survey target device  300  obtained in step S 106  as the coordinate information  122   b  of the surveying information  122  in association with the deviation  122   c  and the distance  122   d.    
     With the use of such a surveying system  1 , the operator can measure the coordinates of each foundation point MP according to single design information  121  to obtain the deviation and the distance regarding each foundation point MP. For example, the operator measures the coordinates of each foundation point MP to obtain a relative position (e.g., deviation and distance) with respect to a boundary side. If the distance does not meet predetermined conditions (e.g., less than a distance compulsorily required by laws), the operator can use the surveying method to reconsider the positions (i.e., the coordinate information)  121   b  of the foundation points MP in the design information  121 . The terminal  100  may be so configured that the terminal storage unit  120  stores therein thresholds of distances in advance, and if a distance calculated fails to meet predetermined conditions at pressing of the RECORD button  151  by an operator, the terminal  100  outputs an alert in the form of sound, display, or the like and does not record the calculated relative position or the surveying information. The terminal  100  may be so configured that, if the boundary points DP have not yet surveyed (e.g., the data corresponding to the boundary points DP is missing in the surveying information  122 ) when an operator selects the RECORD button  151 , the terminal  100  outputs an alert in the form of sound, display, or the like and prompts to survey the boundary points DP. 
     The surveying method according to the embodiment of the present disclosure allows an operator to acquire a relative positional relationship between the position of the survey target device  300  and an intersection CP corresponding to a survey target foundation point by selecting the survey target foundation point from among consecutive foundation points MP as the survey target foundation point via the input unit  140 . This configuration allows the operator to specify the relative position easily and efficiently. 
     By displaying image information and other necessary information as described above on the display unit  150 , the terminal  100  informs an operator of deviations with respect to an intersection (deviations respectively from the reference lines ML 11  and ML 12 ). Based on such information, the operator can easily perform surveying to find out a position corresponding to the survey target foundation point by searching for a position distanced from the intersection CP by a smaller distance or (by zero distance). 
     Batter Board Setting Function 
     Now, an outline of a batter board setting function will be described, which is one aspect of the surveying method, the surveying system, and the surveying program according to an embodiment of the present disclosure. 
     As shown in  FIG.  1   , the batter board  3  includes a plurality of batter board stakes  31  each with a mark LM indicating the position of the corresponding beam top  321 . The altitude indicated by the marks LM is basically common among all the batter board stakes  31 . However, since the lengths of the stakes to be used and the depths of the stakes driven by manual work vary, the work of applying the marks LM to a common altitude is not easy. 
     A procedure for applying the marks LM to such batter board stakes  31  evenly and accurately will be described herein.  FIG.  7    illustrates the relationship between a batter board stake  31  and the altitude of a benchmark BM. In  FIG.  7   , the vertical direction of the drawing represents the height direction of the batter board stake  31 . Here, the length of the batter board stake  31  driven in the ground and the height of the stake top  311  are unknown. The position (including altitude) of the benchmark BM at the site is known and included in the design information, or can be measured at a site. In addition, the altitude difference from the benchmark BM to a current ground GL and the altitude difference from the ground GL to the beam top  321  are known and included in the design information  121 . 
     The operator measures the altitude of the stake top  311  using the surveying device  200  and the survey target device  300 . The altitude of the stake top  311  can be obtained by measuring the altitude of the retroreflective prism  301  as a target and calculating out the altitude of the stake top  311  on the basis of a known height h 5  of sight-line from the retroreflective prism  301  to a distal end of the pole  302  (e.g., the lower end thereof in the example of  FIG.  7   ). Once the altitude of the stake top  311  of the survey target device  300  is found out by the measurement, it becomes possible to calculate out an altitude difference h 4  from the stake top  311  to the beam top  321  using the information on a known altitude difference h 1 , h 2 , or h 3 , where the altitude difference h 1  is an altitude difference between the benchmark BM to the ground GL, the altitude difference h 2  is an altitude difference between the ground GL and the beam top  321 , and the altitude difference h 3  is an altitude difference between the benchmark BM and the beam top  321 . The terminal  100  can display the calculated altitude difference h 4  on the display unit  150 . 
     An exemplary surveying method using the surveying system  1  may be a surveying method of setting a batter board  3  including a batter board stake  31 , a batter board beam  32 , and a leveling string. The surveying method includes, for example: performing benchmark measurement including measuring, with the surveying device  200 , the altitude of a benchmark BM, which serves as a reference height of the batter board  3 ; performing stake top measurement including measuring the altitude of a stake top  311  of a batter board stake  31  installed; and performing beam top position display including calculating a difference in height between the stake top  311  of the batter board stake  31  and a reference height of a foundation (i.e., the ground GL) stored in advance based on the reference height of the foundation, the altitude of the benchmark BM, and the altitude of the stake top  311  of the batter board stake  31 , and displaying the beam top position on the terminal  100 . Accordingly, even if the driven stakes are installed with various lengths and depths, marks LM indicating the positions of the beam tops  321  of the plurality of batter board stakes  31  can be placed accurately, so that the batter board beams  32  and  32  of the batter board  3  can be set efficiently. This configuration allows an operator to even solely measure a stake top  311  with the survey target device  300  and the terminal  100  in a hand and easily make a mark LM via checking, on site, the altitude difference h 4  from the stake top  311  to the beam top  321  on the display unit  150  of the terminal  100 . 
     Leveling String Setting Function 
     Now, an outline of a leveling string setting function will be described, which is one aspect of the surveying method, the surveying system, and the surveying program according to one embodiment of the present disclosure. 
     As illustrated in  FIG.  1   , since a leveling string basically stretches out across two batter board beams  32  and  32  facing each other, a point M 1  to which one end of the leveling string is to be fixed is determined on the top surface of one of the batter board beams  32 , and the one end of the leveling string is fixed to the point M 1  by nailing or any other suitable means. In order to accurately stretch out the leveling string, accurate determination of the position of the point M 1  is necessary. The point on the batter board beam  32 D is not illustrated in the drawings, which corresponds to the point M 1  on the batter board beam  32 A. 
     The point M 1  to which the leveling string is to be fixed is defined on the top surface of the batter board beam  32 . The position of the foundation of a building or any other suitable structure at which a leveling string is to be placed is predetermined and stored in the form of the design information  121 . The position of the foundation of a building at which a leveling string is to be placed is predetermined and stored in the form of the design information  121 , which would be updated, depending on a result of obtaining the relative position of the foundation point MP described above. The position of the foundation of the building is determined by reference sides ML connecting a plurality of foundation points MP, and is shown as the reference sides ML 1  to ML 4  in  FIG.  1    (see also  FIG.  6   ). In this embodiment, the reference sides ML 1  to ML 4  form a closed rectangular region. However, the reference sides ML 1  to ML 4  are mere line information according to the design information  121  and are formed by supporting both ends of a leveling string by batter board beams  32  and  32  at a site. 
     The terminal  100  is applicable to searching for a point at which an imaginary extension VL (e.g., the imaginary extension VL 1 , VL 2 ) of a reference side ML and the top surface of a batter board beam  32  intersect with each other, using the surveying device  200  and the survey target device  300 . For example, an operator moves the survey target device  300  in order to search for the point M 1  via checking, on the display unit  150  of the terminal  100 , how far the position indicated by the survey target device  300  is away from the imaginary extension VL 2 , and finds and determines the point without positional deviation as the point M 1 . After determining the point M 1 , the operator can set a fixing point of the leveling string by nailing or any other suitable means at the position. 
     In this manner, the surveying method according to this embodiment may be, for example, a surveying method of setting a batter board including a batter board stake, a batter board beam, and a leveling string, using the surveying system  1 . The surveying method includes: performing benchmark measurement including measuring the position of a benchmark BM serving as a reference using a surveying device; performing imaginary extension calculation including calculating an imaginary extension VL which is an extension of a reference side ML indicating a point at which a leveling string is to be stretched out; and performing leveling string guide including displaying a distance between a surveyed point and the imaginary extension on a terminal. Accordingly, the position at which the leveling string is to be fixed can be determined more accurately and the leveling string can be stretched out accurately and efficiently. 
     As described above, in this embodiment, a surveying method and a surveying program using a surveying system  1  including a surveying device  200  and a terminal  100 . The surveying method and the surveying program include: receiving, by the terminal  100 , a result of selecting a survey target foundation point from among a plurality of consecutive foundation points MP; obtaining an intersection CP between a reference line ML 10  and a boundary side DL set in advance, the reference line ML 10  connecting the survey target foundation point and an adjacent foundation point adjacent to the survey target foundation point; and outputting, in association with the survey target foundation point, a relative positional relationship between the intersection CP and a position of a survey target device  300  surveyed by the surveying device  200  for the survey target foundation point. Since the intersection serving as the reference of the relative position is calculated out in response to selecting the survey target foundation point, an operator can easily and efficiently acquire the position at the site. 
     The embodiment of the present disclosure has been described above, but the aspects of the present disclosure are not limited to the embodiment. 
     For example, while the configuration using the surveying device  200  and the terminal  100  has been described in this embodiment, the surveying device  200  and the terminal  100  may be configured integrally or the functions of the surveying device  200  and the terminal  100  may be implemented by using three or more devices. The terminal  100  and the survey target device  300  may be configured integrally or individually. 
     The surveying device  200  and the survey target device  300  are configured as physically individual hardware but as being capable of fulfilling the function of surveying in cooperation with each other. Therefore, the survey target device  300  may be interpreted as a part of the configuration of the surveying device  200 . For example, another example of the surveying device  200  is a surveying device using a global navigation satellite system (GNSS). In this case, a GNSS receiver can be used as a device with the functions of the surveying device  200  and the survey target device  300 . 
     The relative position of a foundation point MP may be measured after setting a batter board  3 . As an alternative, the relative position indicating a distance may be measured before or after stretching out a leveling string in setting a batter board  3 . 
     A foundation point may be a reference point in a building, a structure, or any other suitable design object. 
     The terminal control unit  110  is not limited to displaying an obtained relative position of a survey target foundation point on the display unit  150  but may output the relative position by other means, for example, by other output means of the terminal  100  or transmitting information on the relative position to another device (e.g., the surveying device  200 ). 
     By displaying the foundation point identification information  121   a   1  and  122   a   1  assigned to the foundation points MP and the boundary point identification information  121   a   2  and  122   a   2  assigned to the boundary points DP on the display unit  150  at the time of selecting a survey target foundation point or performing the other operation, an operator can easily grasp the foundation point MP for which the operator is currently operating. On the other hand, the foundation point identification information  121   a   1  and  122   a   1  and the boundary point identification information  121   a   2  and  122   a   2  are not necessarily displayed on the display unit  150  at the time of selecting a survey target foundation point or performing the other operation, depending on the layout of a screen display, etc. 
     The identification information  121   a  on the foundation points MP and the boundary points DP included in the design information  121  may be assigned in advance before being acquired from an external device or equipment, or may be assigned after a user, such as an operator, has acquired the design information  121 .