JP2006242646A - Earth fall monitoring system and rock mass anomaly measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To predict the risk of an earth fall by safely and simply monitoring the behavior of a rock mass with satisfactory precision by means of laser irradiation and by efficiently monitoring cracks in the rock mass by the combination of the behavior of the rock mass by means of laser with photograph data. <P>SOLUTION: This earth fall monitoring system is equipped with: a monitoring condition storage means for storing monitoring conditions related to an anomaly at a measurement point of a rock mass which is a monitoring object; a data collection means for collecting coordinate data on the measurement point by means of reflected laser light while collecting image data on the rock mass; and an anomaly detection means for calculating an anomaly at the measurement point based on the coordinate data while determining whether there is a sign of anomaly by referring to the monitoring conditions and executing a photo survey based on the image data to update the measurement point if the sign of anomaly is determined to exist. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rock mass behavior observation and a mutation measurement technique in a place where there is a risk of rock mass collapse.

  Conventionally, as a technique for monitoring the collapse of a rock mass, a technique has been proposed in which a wire is directly wound around a rock mass and one end thereof is made a retraction type, and the movement of the rock mass is monitored by the amount of retraction. (For example, see Patent Document 1.)

  However, wrapping a wire around a rock mass to monitor the behavior of the rock mass and predict the collapse of the rock mass is a heavy burden and is dangerous. For this reason, it is conceivable to take a rock mass from a remote location and detect the movement to monitor the collapse.

  As a technique for measuring cracks using a photograph, for example, in Patent Document 2, in order to predict a collapse of a tunnel or the like, a laser serving as a reference position is irradiated to the excavation cross section, and the crack location is photographed together with the laser irradiation position. Thus, a technique for acquiring the coordinate position of the crack and calculating the volume of the block body surrounded by the crack surface and the crack surface has been proposed.

However, the technique described in Patent Document 2 is to accurately measure a crack based on a reference point by laser irradiation when a crack has already occurred. In order to monitor whether or not a crack has occurred, it is necessary to compare photographic data in time series, and the burden is great. In addition, it usually requires a great deal of labor to monitor whether or not a crack is expanding for each of the rock blocks having a very large number of minute cracks. Even if monitoring processing such as generation of a new crack or expansion of a crack is executed by the computer, a large load is applied to the computer.
JP-A-10-206198 JP-A-11-62465

  The present invention has been made in view of the above-mentioned circumstances, and it is possible to monitor the behavior of a rock mass accurately and safely by laser irradiation, and efficiently by combining the behavior of the rock mass by laser and photographic data. An object of the present invention is to provide a fall monitoring system and a rock mass variation measuring method capable of predicting the risk of fall by monitoring cracks in the rock.

A feature of the present invention is that a non-prism type total station (data measuring means) is used first. Since the conventional total station required a prism for observation, it was necessary to enter the dangerous rockfall location, but in recent years, with the advancement of surveying instrument technology, high-precision observation of about 200 m has become possible at the non-prism total station. As a result, work safety is improved and efficiency can be improved.
Next, the subject (rock mass) was observed from different directions. Usually, it was decided to acquire data for improving reliability by measuring from two locations.

  In addition to acquiring 3D coordinates, the situation of the subject was photographed with a digital camera at a fixed point, and fused with the digital image to measure the variation.

  Furthermore, digital photogrammetry (indirect measurement) is performed using a stereo pair digital image acquired when a predetermined abnormality sign is generated. The most important issue in observing rock mass behavior is how to deal with behaviors and cracks outside of the originally assumed location, but monitoring is possible within the digital image area even if changes occur outside the zoning range. It is possible to measure the behavior back in time by effectively using the data. At this time, by adding or changing the orientation point (pass point), the date and time of the first acquired image can always be used as the time series starting point.

  Specifically, the collapse monitoring system according to the present invention collects coordinate data of measurement points by means of monitoring condition storage means for storing monitoring conditions relating to variation of measurement points of the rock mass to be monitored, and reflected light of the laser. Data collection means that collects image data of rock masses, calculates the variation of the measurement point based on the coordinate data, determines the presence or absence of abnormal signs by referring to the monitoring conditions, and was determined to have abnormal signs In this case, the apparatus includes a mutation detection unit that performs photogrammetry based on image data and updates a measurement point.

  Also, the rock mass variation measuring method according to the present invention is a rock mass to be monitored using the coordinate data of the rock mass collected by the laser measuring means and the image data collected by the imaging means provided in the laser measuring means. A method of detecting and measuring a mass variation, determining one or more measurement points in a rock mass, irradiating a laser to the measurement point and collecting coordinate data and A data accumulation stage for collecting and accumulating image data, a stage for calculating presence / absence of abnormalities by calculating a rock mass variation based on the accumulated coordinate data, and a stage for outputting the judgment result When a predetermined abnormality sign is detected, an abnormality sign detection step is performed in which photogrammetry is executed based on the image data to update the measurement point.

  The present invention performs efficient mutation detection by combining so-called non-prism laser measurement and photogrammetry. Always monitor the measurement point for changes by laser measurement, and if a sign of abnormality is detected, perform photogrammetry and find a new crack. On the other hand, laser measurement is performed.

  Here, the “mutation” means any abnormality that occurs in the rock mass to be monitored, and includes a change in the rock mass position, that is, a displacement, as well as generation of a new crack or expansion of a crack.

  The “abnormality sign” detects a minute mutation before reaching a critical level. For example, if there is a mutation of 10% with respect to the critical level, it is managed as having an abnormal sign. Is.

  In the collapse monitoring system according to the present invention, the monitoring condition storage means stores the measurement distance and the resolution of the image data in association with each rock type, and the data collection means stores the monitoring condition based on the distance from the measurement point. The resolution of the image data is extracted with reference to the storage means, and the image data is collected at an imaging magnification that satisfies the resolution.

  In the present invention, the microscopic crack is monitored for each rock mass so that the imaging magnification is determined not only by the measurement distance but also by the rock mass type. As a result, it is possible to store image data with appropriate resolution for each type of rock mass, such as a rock mass that is easy to collapse even with a slight crack or a rock mass that is not.

  In the collapse monitoring system according to the present invention, the monitoring condition storage means stores the mutation speed and the measurement period in association with each rock type, and the mutation detection means calculates the mutation speed based on the history data of the mutation. And updating the measurement cycle.

  In the present invention, the measurement cycle is made variable according to the speed of mutation to improve the efficiency and accuracy of monitoring.

  In the collapse monitoring system according to the present invention, the monitoring condition storing unit stores the incident angle range of the laser in association with the error classification, and the data collecting unit collects the incident angle information of the laser for each coordinate data to detect the mutation. The means refers to the monitoring condition storage means based on the incident angle information, extracts an error classification of the coordinate data, and determines whether there is an abnormality sign using the monitoring condition corrected based on the error classification. It is characterized by.

  The accuracy of the acquired coordinate data differs depending on whether the laser beam is irradiated vertically on the object to be monitored or if the laser beam is irradiated at an angle. Therefore, in the present invention, a monitoring condition is defined for each error category based on the incident angle of the laser, and the presence / absence of an abnormality sign is determined.

  If the photogrammetry is carried out or not carried out only by finding an abnormality sign by laser measurement, if an inappropriate measurement point is first selected, accurate monitoring cannot be performed. For this reason, it is better to perform photogrammetry with a predetermined period longer than laser surveying regardless of the presence or absence of abnormal signs, but preferably the incidence of laser when taking coordinate data of measurement points during this photogrammetry period It is good to make it variable according to the angle. When the measurement error based on the incident angle of the laser is large, it is possible to monitor with higher accuracy by shortening the period of the photogrammetry.

  According to the present invention, the behavior of a rock mass can be monitored accurately and safely by laser irradiation. In addition, the combination of laser rock behavior and photographic data enables efficient monitoring of rock cracks and accurate prediction of collapse risk.

  Embodiments of the present invention will be described below. FIG. 1 is a system configuration diagram for executing a rock mass variation measurement method according to a first embodiment of the present invention. In this figure, in the variation measuring method of the present embodiment, a non-prism total station (laser measuring means) 21, a digital camera (imaging means) 22, and a computer for processing images taken by the digital camera 22 are processed. Using digital image analysis software (not shown).

  The digital camera 22 is attached to the total station 21 and can shoot toward the total station. Note that a total station having an imaging function may be used instead of providing a digital camera individually. Of course, it is also possible to carry out the operation in such a manner that an operator stands at the same position as the installation position of the total station 21 at the time of collecting coordinate data and the monitoring object is photographed by the digital camera 22.

Hereinafter, a method for measuring variation of a rock mass using this system will be described with reference to FIG.
First, as a site reconnaissance, the current state of geology is confirmed and a reference point (total station installation position) is selected (S101). Then, the geological survey engineer confirms the rock fall pattern and classifies the fixed rock point and the area (zoning area) where rock fall may occur (S102). Next, an observation plan such as an observation cycle is made based on the possibility and risk of rock fall (S103).

  Then, a total station is set as a reference point for on-site observation, and a pass point (rating point) is selected at a location where rockfall collapse is predicted (S104). The method of selecting this pass point will be described in detail with reference to FIGS.

  Fig.3 (a) is the figure which looked at the total station and the rock mass from the horizontal direction. Moreover, FIG.3 (b) is the figure which looked at the rock block from the back of the total station. The total station collects coordinate data of a specific pass point of the rock block from at least two reference positions (S position, T position). For example, in FIG. 3A, a total station is installed at the S position outside the danger area of falling rocks, and a fixed pass point is set for the fixed rock mass point. This is the point that becomes the reference point for measuring the movement of the rock mass. A plurality of fixed pass points may be provided. This is because the bedrock may not be fixed in the future.

  An arbitrary characteristic point in the zoning area is set as an observation point. The pass point of this observation point is a characteristic point as shown in FIG. For example, crack intersections, corners, and edges. When observing the growth of a crack, a plurality of points including both ends and corners of one crack are set as pass points (1A1 to 1A4 in FIG. 4B). This pass point is marked on the sketch and the image data taken with the digital camera along with the characteristic crack shape. Further, when a new crack occurs, pass points (1B1 to 1B3) are added to the feature points of the crack as shown in FIG.

  In addition to zoning area passpoints, fixed passpoints are set by calculating the relative position of the zoning area passpoints based on the fixed passpoints, thereby accurately calculating the movement of the zoning area relative to the stationary rock mass. It is to do. In addition, a stereo pair is formed by taking a digital photograph of the zoning area from both the S position and the T position toward the same pass point, and digital photogrammetry and an ortho image can be created by digital image analysis software.

  Next, as on-site observation, pass point observation and digital image acquisition are performed (S105). Specifically, the pass point is observed by collimating the pass point with reference to a sketch or image data by a non-prism total station to obtain three-dimensional coordinate data (S105a). The digital image is acquired by taking a digital image of a place where collapse is expected (S105b).

  Based on this observation data, whether or not partial collapse has occurred is confirmed (S106). If partial collapse has occurred, the passpoint is changed or added, and data is collected (S107). In addition, digital photogrammetry using digital images acquired in the past is performed (S108), collapse simulation and countermeasure work are examined using image analysis software or the like (S109 to S111), and the result is output as a report. .

  On the other hand, if partial collapse has not occurred, the displacement of the observed coordinates is calculated in the X-axis, Y-axis, and Z-axis directions (S112). (S113), and the determination result and countermeasure work are output as a report (S114).

  As described above, according to the present embodiment, it is not necessary to enter a rockfall danger point, and safe observation is possible. In addition, rock mass behavior can be accurately and quantitatively determined by actual measurements from multiple locations using a non-prism total station. In particular, since a digital image of a subject (rock mass) is also acquired, it is possible to create an ortho image and interpret a photograph. In addition, digital photogrammetry is also possible by acquiring digital images from observation points. It should be noted that three images can be acquired from different reference points toward the same pass point and analyzed using a triplet image.

  Furthermore, since the orientation point (pass point) is added or changed depending on whether partial collapse has occurred or not, it is possible to make a quantitative determination using the date and time of the first acquired image as the time series starting point.

  Further, it is possible to perform digital photogrammetry by developing “survey to express” by fusing with a digital image as well as acquiring three-dimensional coordinates and making the photographing location the same as the observation location. As a result, the business effect can be expected by expanding from “Surveying just to measure” to “Surveying to express”.

  Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram of the collapse monitoring system according to the present embodiment. Here, the collapse monitoring system 1 transmits a total station (TS, data collecting means) 21 that measures a distance by a laser, a digital camera 22 that takes a picture of a zoning area, and the collected data to a server via a communication network 4. A transmission terminal device (data transmission means) 23 and a server 10 that performs collapse monitoring calculation using collected data. The transmission terminal device 23 may be a portable terminal such as a PHS.

  The server 10 inputs transmission / reception unit 11 that transmits / receives data to / from the transmission terminal device 23, a central processing unit 12 that processes received data, a storage unit 13 that stores data, and setting data such as monitoring conditions. In addition, an input unit 14 and an output unit 15 are provided as a user interface for outputting a calculation result.

  Further, the central processing unit 12 is a transmission / reception processing unit (function) 121 for exchanging data with other devices via the transmission / reception unit 11, and an input / output processing unit for exchanging data with the input unit 14 and the output unit 15 ( Function) 122, monitoring condition setting means (function) 123 for saving the inputted monitoring conditions in the storage unit 13, data input means (function) for receiving the measurement data by the TS 21 and the image data by the camera 22 and saving them in the storage unit 13 ) 124, data output means (function) 125 for transmitting image data with a pass point mark to the camera 22, monitoring period setting means (function) 126 for setting / changing the monitoring period based on the measurement data, path Path point setting means (function) 127 for setting / updating points, mutation detection for detecting mutations in rock masses based on measurement data Stage (function) 128, and includes a photogrammetric means (function) 129 for performing a survey by image analysis of the captured image data.

  In addition, the storage unit 13 includes a monitoring condition file (monitoring condition storage unit) 131 that stores monitoring condition data, an input data file 132. That stores coordinate data sent from the TS 21. It has an image data file 133 that stores image data sent from the camera 22 and an operation result file 134 that stores operation results.

Next, the operation of the collapse monitoring system 1 having the above configuration will be described.
<Monitoring condition setting stage>
Monitoring conditions are stored in advance in the storage unit 13 of the server 10 via the input unit 14. The monitoring condition data input from the input unit 14 is registered in the monitoring condition file 131 of the storage unit 13 via the input / output processing unit 122 and the monitoring condition setting unit 123 of the central processing unit 12. FIG. 6 is a data configuration example of the monitoring condition file 131.

  Monitoring items and standard values of monitoring standards are stored for each rock mass type. The rock mass type refers to a type such as granite or rhyolite, but a standard may be set in consideration of the location situation.

  Examples of monitoring items include the movement amount of the coordinate value of the pass point, the crack length for each shape, and the like. Further, as an abnormality detection condition, a change in a predetermined ratio (for example, 10%) with respect to a standard value is monitored, or an abnormality is monitored based on a change speed.

  Further, for each abnormal rank, a coordinate data collection cycle by TS, an image data collection cycle by a camera, and a photogrammetry execution cycle using image accumulation data are set. This abnormal rank is set based on, for example, the amount of movement relative to the standard value, the size of the crack length, and the change speed.

  In the non-prism system, a measurement error occurs depending on the incident angle of the laser of TS 21, that is, the angle when the subject is irradiated with the laser. Therefore, the error and the error classification are stored for each incident angle. In FIG. 6, the incident angle refers to the angle of the laser with respect to the perpendicular. Therefore, the closer to 90 degrees, the more irradiation is in the horizontal direction, and the irradiation is upward as the angle becomes smaller.

<Measurement preparation stage>
The place where the TS 21 for laser measurement of the zoning area to be monitored is determined. This preparation method is the same as in the first embodiment.

  At this time, the camera 22 takes a picture of the zoning area and transmits the image data to the server 10. This image data is stored in an image data file and a pass point is selected by a collapse analysis specialist, and an identification number is assigned to each pass point and is described on the image file. The pass point identification number can be identified by attaching a unique code to a part of the identification number for pass points belonging to the same crack.

  In addition, based on the image data collected at this stage, the standard values of the monitoring conditions in FIG. Specific monitoring conditions may be set.

<Data collection stage>
Coordinate data and image data are collected at a period set in the monitoring condition file. At this time, the image data with the pass point is transmitted from the server 10 to the camera installed in the field via the data output means 125 and displayed on the camera. This image data is displayed after being adjusted to the magnification of TS21 so that the operator can recognize it when collimating with TS21.

  The worker confirms the pass point displayed in the image data, collimates with TS21, and irradiates the pass point position with laser to collect coordinate data. The collected coordinate data is sent to the server 10 through the transmission terminal device 23 together with the reference altitude value and the incident angle information of each measurement point, and stored in the input file 132 by the data input means 124.

  FIG. 7 is a data configuration example of the input data file 132. Distance, incident angle, and coordinate data are stored for each pass point identification number. In addition, an error classification is assigned corresponding to the incident angle.

<Mutation detection stage>
The mutation detection unit 128 detects an abnormality according to the conditions of the monitoring condition file 131 based on the data of the input data file 132. The calculation result of the mutation detection unit 128 is stored in the calculation result file 134 of the storage unit 13. FIG. 8 is a data configuration example of the calculation result file 134. For each passpoint identification number, the amount of movement (mutation) relative to the initial data, and the amount of movement change (mutation speed) based on the previous measurement data are calculated. The flag for each detection condition is turned on. In this calculation, an error is determined on the assumption that a predetermined measurement error exists in consideration of an error based on an incident angle.
Similarly, the crack length, the rate of change thereof, and the abnormal flag are set for the crack.

  When the abnormality flag is set by this mutation detection process, the photogrammetry means 129 is activated.

  When activated, the photogrammetry means 129 extracts image data from the past to the present of the image data file 133, and calculates the presence / absence of a new crack and the rate of change by image analysis. The mutation detection means updates the pass point through the pass point setting means 127 based on the calculation result, and makes adjustments such as increasing the monitoring cycle.

  Then, an alarm having a predetermined content is output according to the abnormality rank. This alarm may be output to the operator on the server 10 side via the output unit 15, or output to a terminal device (not shown) of a private house affected by the zoning area via the communication network 4. May be performed.

Next, the process of the mutation detection step will be described in detail with reference to FIG.
First, after the data is input, the mutation detecting means 128 is activated, and the input coordinate data is used to calculate the movement amount and crack length of each measurement point and the rate of change compared with past data (S201). Then, compared with the abnormality detection condition 1 of the monitoring condition file 131 (S202), if there is an abnormality, that is, if the absolute amount of mutation exceeds a predetermined value (“Y” in S203), abnormality detection 1 A flag is set (S204). Further, compared with the abnormality detection condition 2 of the file 131 (S205), if there is an abnormality, that is, if the change rate of the mutation exceeds a predetermined value (“Y” in S206), the abnormality detection 2 flag. Is set (S207).

  The above processing is performed for all the measurement points, and if any abnormality detection flag is set (“Y” in S208), the monitoring cycle setting means 126 is activated and the data (coordinate data and image data) is The input cycle and photogrammetry (abnormality detection based on image data) are changed (S209). Note that the next surveying time may be set instead of the cycle. If it is determined that the degree of danger is high depending on the state of the abnormality flag, a predetermined warning such as an evacuation recommendation is output (S210, S211).

  Then, the photogrammetry means 129 is activated, and detailed measurement of the presence / absence of a new crack and the change of the crack is executed as compared with the past image data (S212). As a result of this processing, when a new mutation is found, the pass point setting means 127 is activated to add a measurement point (S213, S214).

  On the other hand, if the abnormality detection flag is not set in step S208, it is determined whether or not the next photogrammetry time has come. If the photogrammetry time has come, the photogrammetry processing in step S212 and subsequent steps. Is executed (S215).

  As shown in the process of FIG. 9, by combining anomaly monitoring by laser measurement and anomaly monitoring by photogrammetry, high-precision monitoring can be performed without performing error correction by the incident angle of laser measurement. If the data collection cycle or photogrammetry cycle can be variably set, more effective monitoring can be performed.

  According to the present embodiment, by observing the variation in the coordinate data of the subject in the zoning area, an abnormality sign such as the amount of movement of the pass point and the size of the crack is detected, thereby performing the photo measurement. Therefore, the load can be reduced as compared with the case where image data is always analyzed. In addition, detection of an abnormal sign at a certain pass point is used as a trigger to detect other cracks and update the pass point. Can monitor for abnormalities.

  In the first embodiment, the partial collapse is used as a trigger to change the pass point or perform photogrammetry. However, according to the present embodiment, the update of the pass point or the like before the partial collapse occurs. Therefore, more accurate and safe monitoring can be performed.

  In this embodiment, when monitoring collapse using a non-prism total station, even if the coordinate data has an error based on the incident angle of the laser, high accuracy monitoring is realized by combining laser measurement and photogrammetry. However, using the technology of the volume calculation system of Japanese Patent No. 3645253, a highly accurate mutation calculation may be executed by correcting the error due to the incident angle with respect to the input coordinate data.

1 is a system configuration diagram for executing a rock mass variation measurement method according to a first embodiment of the present invention; FIG. It is a flowchart which shows the procedure of the variation measurement method of the rock mass by the 1st Embodiment of this invention. It is explanatory drawing of the method of the passpoint setting by the 1st Embodiment of this invention. It is explanatory drawing of the feature point of the pass point by the 1st Embodiment of this invention. FIG. 4A is an image example of an observation point (measurement point), and FIG. 4B is an explanatory diagram for adding a pass point. It is a block diagram of the collapse monitoring system by the 2nd Embodiment of this invention. It is a data block diagram of the monitoring condition file 131 of FIG. It is a data block diagram of the input data file 132 of FIG. It is a data block diagram of the calculation result file 134 of FIG. It is a flowchart which shows the process sequence of the variation | mutation detection means of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Collapse monitoring system 10 Server 11 Transmission / reception part 12 Central processing unit 13 Memory | storage part 14 Input part 15 Output part 21 Total station 22 Camera 23 Transmission terminal device 121 Transmission / reception processing means 122 Input / output processing means 123 Monitoring condition setting means 124 Data input means 125 Data output means 126 Monitoring cycle setting means 127 Pass point setting means 128 Mutation detection means 129 Photogrammetry means 131 Monitoring condition file 132 Input data file 133 Image data file 134 Calculation result file

Claims (6)

Monitoring condition storage means for storing monitoring conditions regarding the variation of the measurement point of the rock mass to be monitored, data collecting means for collecting the coordinate data of the measurement point by reflected light of the laser and collecting image data of the rock mass,
Based on the coordinate data, the variation of the measurement point is calculated and the presence or absence of an abnormality sign is determined with reference to the monitoring condition. If it is determined that there is an abnormality sign, a photograph is taken based on the image data. Mutation detection means for executing surveying and updating measurement points;
A collapse monitoring system characterized by comprising The monitoring condition storage means stores the measurement distance and the resolution of the image data in association with each rock mass type,
The data collection means extracts the resolution of the image data with reference to the monitoring condition storage means based on the distance from the measurement point, and collects the image data at an imaging magnification satisfying the resolution. 1. The collapse monitoring system according to 1.   The monitoring condition storage means associates and stores a mutation rate and a measurement cycle for each rock mass type, and the mutation detection means calculates a mutation rate based on the calculated history data of the mutation, and calculates a measurement cycle. The collapse monitoring system according to claim 1, wherein the collapse monitoring system is updated. The monitoring condition storage means stores the incident angle range of the laser in association with the error classification,
The data collection means collects laser incident angle information for each coordinate data,
The variation detection means refers to the monitoring condition storage means based on the incident angle information, extracts an error classification of the coordinate data, and uses the monitoring conditions corrected based on the error classification to check for signs of abnormality The collapse monitoring system according to any one of claims 1 to 3, characterized by: A method for detecting and measuring a variation of a rock mass to be monitored using coordinate data of a rock mass collected by a laser measuring means and image data collected by an imaging means provided in the laser measuring means. ,
Determining one or more measurement points in the rock mass;
A data accumulation stage for collecting coordinate data by irradiating a laser to the measurement point and collecting and storing image data of the rock mass;
Calculating the rock mass variation based on the accumulated coordinate data and determining the presence or absence of abnormality, and outputting the determination result;
When a predetermined predetermined abnormality sign is detected, an abnormality sign detection stage for performing photogrammetry based on the image data and updating a measurement point;
A method for measuring variation of a rock mass, characterized by comprising: In the data accumulation stage, for each coordinate data, collect the incident angle information of the laser at the time of the coordinate data collection,
6. The rock mass variation measurement method according to claim 5, wherein, in the abnormal sign detection step, photogrammetry is executed at a cycle determined based on an error based on the incident angle information.