JP2017026577A - Creating method for three-dimensional survey photographs - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a creating method for three-dimensional survey photographs by which high-precision three-dimensional survey photographs for use in construction management can be created even when plane photographs taken from the sky above using UAV mounted with a camera of around 12 million pixels in resolution are used.SOLUTION: A three-dimensional survey photograph creating method works in this way. In a construction site, multiple reference points S having three-dimensional coordinates are set at prescribed intervals; a UAV 10 (multi-copter) mounted with a camera 3 is let fly to take multiple different plane photographs containing common points P from the sky above; this procedure is taken at each of the multiple common points P; the multiple different plane photographs containing the common points P are stacked one over another while causing the common points P to agree with one another for each common point P to create plane synthesized photographs having height information on the construction site based on three-dimensional information on the reference points S; and these are used as three-dimensional survey photographs.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for creating a three-dimensional survey photograph using a planar photograph taken by a UAV (multicopter) equipped with a camera.

  Currently, 3D objects are photographed from multiple observation points, disparity information of singular points in 2D images is analyzed to obtain point cloud coordinates (x, y, z), and 3D survey photographs are created. Surveying technology has been developed.

  In this method, surface information (surface) is created by connecting all point group coordinates.

  In the photogrammetry technique, conventionally, photographing from the sky has been performed using an expensive topographic surveying UAV (Unmanned Aerial Vehicle: multi-copter) equipped with a digital camera.

  A UAV equipped with this digital camera has an introduction cost as high as about 10 million yen. For example, at a construction site where earthwork is performed, the price is an obstacle to the introduction. The reason why the UAV becomes expensive is that the mounted camera is a digital camera having a telephoto performance, for example, so that the mounting weight becomes heavy, the UAV body supporting this becomes heavy, and the propeller that makes the heavier aircraft fly Can be increased in size.

  Therefore, in the actual earth work management (banking volume (bank height) management and cut volume management), we request a professional surveyor who owns an expensive UAV to take a picture of the sky. A three-dimensional survey photograph was created by compositing the photographed sky photographs, and the earthwork amount management which changed sequentially was performed.

  Therefore, it takes time to capture the sky by a specialized surveyor, create a 3D survey photo by combining the captured sky photos, and create a 3D survey model by converting the created 3D survey photo into point cloud data It took a lot of time to be done. Furthermore, the cost of creating 3D survey photographs and 3D survey models was also expensive.

  Therefore, an inexpensive UAV with a resolution of about 12 million pixels and equipped with a lightweight camera, which is at most about 300,000 yen, has been developed. Since the price is low, it is possible to purchase UAV directly even at the construction site. In addition, since the UAV owned by the construction site itself is used, it is possible to take a picture of the sky by flying it at the desired timing, and immediately synthesize the photographed plane photo at the site to create a 3D survey photo. And 3D survey models can be created, the time required to create 3D survey photos and 3D survey models is significantly reduced.

  However, there is a problem in the planar photograph by the sky photography using a camera with a resolution of about 12 million pixels, and there is a problem that the created three-dimensional survey photograph cannot easily determine the amount of earthwork.

  Actually, in the earth work management in earth work, the error of the height of the earth work is in the range of about ± 10 cm at most. This ± 10 cm is about 10 cm of dirt on the soil surface formed by crawlers of heavy machinery that lays the soil in earthwork, or large tires, etc., so the soil surface formed by these crawlers The unevenness and the height of the tire marks are defined as allowable errors.

  As a result of verification by the present inventor, in a three-dimensional survey photograph based on a plane photograph taken with an inexpensive UAV using a camera with a resolution of about 12 million pixels, the height error of the earthwork amount is about 1 m at the maximum. Survey photos that contain such errors cannot be used for earthwork management.

  Here, focusing on the disclosed technology, Patent Document 1 discloses an optical measurement method for obtaining three-dimensional coordinates of a large number of measurement points on the surface of a measurement object. Specifically, the surface of the measurement object is irradiated with a pattern sequence consisting of multiple different patterns by a projector, the image sequence of the surface of the measurement object irradiated with the pattern sequence is photographed by a camera system, and the image sequence is evaluated. By doing so, the three-dimensional coordinates of the measurement point are obtained. At least the translational acceleration and / or rotational acceleration of the projector, camera system and / or measurement object at least during the exposure time of the individual images of the image sequence, each having a plurality of values during the exposure time of each individual image of the image sequence In particular, it is measured at a measurement rate at which a large number of values are detected for acceleration. This measures the movement of the projector, the camera system and / or the measurement object that causes blurring and / or motion blur in each individual image of the image sequence that occurs during the exposure time of each individual image of the image sequence It can be taken into account when specifying the three-dimensional coordinates using an algorithm based on the acceleration that has been made.

  However, even with this optical measurement method, even when using the above-mentioned problem, that is, when using a plane photograph by aerial photography using a UAV equipped with a camera with a resolution of about 12 million pixels, it is used for accurate construction management. The problem of creating 3D survey photographs cannot be solved.

Special table 2013-531237 gazette

  The present invention has been made in view of the above-described problems, and even when a plane photograph obtained by aerial photography using a UAV equipped with a camera having a resolution of about 12 million pixels is used, a tertiary that is used for accurate construction management. It is an object of the present invention to provide a method for creating a three-dimensional survey photograph that can create a former survey photograph.

  In order to achieve the above object, a method for creating a three-dimensional survey photograph according to the present invention provides a UAV (multi-copter) equipped with a camera by installing a plurality of reference points having three-dimensional coordinates at predetermined intervals on a construction site. Fly and take a number of different plane photographs including common points from the sky, and perform this for each of the plurality of common points. For each common point, a common point corresponding to the plurality of plane photographs including the common point is taken. The images are superimposed while being matched, and a plane composite photograph having the three-dimensional information of the construction site based on the three-dimensional information of the reference point is created, and this is used as the three-dimensional survey photograph.

  The method for creating a 3D survey photo of the present invention creates a 3D survey photo from a plane photo taken with an inexpensive UAV equipped with a camera having a resolution of about 12 million pixels. One feature of this creation method is that a plurality of reference points having three-dimensional coordinates are set in the imaging area at predetermined intervals. In addition, a plurality of different planar photographs including common points are taken from the sky, and the plurality of planar photographs including the common points are superimposed while matching the corresponding common points. One of the other features is to superimpose such planar photographs for each point, synthesize the superimposed planar photographs, and create a planar composite photograph having a plurality of reference points having three-dimensional coordinates. I am trying.

  Depending on the number of planar photographs to be superimposed, the number of image combinations differs when processing from point photographs to point cloud data. According to the present inventors, it has been found that the number of superimposed planar photographs greatly affects the accuracy of the three-dimensional survey photograph.

  When superimposing a plurality of planar photographs, each planar photograph has a common point in a part thereof, and the planar photographs are superimposed while matching the common points.

  That is, the “common point” is a point that becomes a reference for overlaying a plurality of planar photographs, and may be referred to as a “photographing point” or the like.

  By superimposing and synthesizing a plurality of plane photographs (data) (creating composite data), even if one photograph was taken with a camera having a resolution of about 12 million pixels, the composite photograph (data) The accuracy of is improved.

  A large number of common points exist in the planar composite photograph area, and a plurality of planar photographs are superimposed on each common point to form a planar composite photograph, which becomes a three-dimensional survey photograph. For example, there are a large number of common points in which common points are arranged at grid grid points in the shooting target area, and at each common point, a composite photo (data ) Is formed, and the composite photograph is developed in a plane to form a planar composite photograph (data). When creating a three-dimensional survey photograph from a large number of photographed planar photographs (data), the photograph can be created by incorporating the planar photograph (data) into cloud image processing software.

  In this plane composite photograph, there are a plurality of reference points having three-dimensional coordinates at predetermined intervals. According to the present inventor, it has been specified that if the distance between the reference points is too long, the three-dimensional information is insufficient and the accuracy of the planar composite photograph is lowered.

  By applying the 3D survey photo creation method of the present invention, the construction site owns an inexpensive UAV equipped with a camera with a resolution of about 12 million pixels, and takes a plane photo by flying the UAV at a desired timing. In addition, it is possible to produce a three-dimensional survey photograph by superimposing each plane photograph in a short time, and developing and synthesizing them in a plane.

  Here, with the tolerance of the height of the pressure-contact mark generated by the crawler used as a traveling device for leveling equipment used at the construction site, the number of overlapping of a plurality of plane photographs having a common point, between adjacent reference points It is preferred to set the distance, flight altitude, and camera pixel count.

  As described above, since the height of the press-contact mark generated by the crawler is about ± 10 cm, the number of overlays of a plurality of plane photographs and the like with this as an allowable error is set.

  First, regarding the number of superimposed planar photographs having a common point, it is desirable to superimpose nine or more planar photographs.

  As a result of verification by the present inventor, it has been found that the accuracy error of the three-dimensional survey photograph satisfies about ± 10 cm or less when the number of superimposed planar photographs having common points is nine. Nine or more.

  Further, the distance between adjacent reference points is preferably 100 m or less.

  As a result of verification by the present inventor, it has been found that when the distance between the reference points having the three-dimensional coordinates is 100 m, the accuracy error of the three-dimensional survey photograph satisfies about ± 10 cm or less. Therefore, the distance between the reference points is set to 100 m. It is defined as follows.

  Furthermore, it is desirable that the flight height of the UAV is in the range of 40 m ± 4 m.

  The range and resolution of an image to be captured vary depending on the UAV flight altitude. That is, when the flight altitude is high, the imaging range is widened while the resolution is low, and when the flight altitude is low, the opposite is true.

  As a result of verification by the present inventor, it is known that the accuracy error of the three-dimensional survey photograph satisfies about ± 10 cm or less when the flight height of the UAV is 40 m. Therefore, the flight altitude is defined as 40 m.

  Even if you always try to manage the flight altitude to "40m", the altitude will rise and fall slightly depending on wind conditions, etc., so about 10% of 40m, that is, the range of 40m ± 4m is the preferred flight altitude. is there.

  The method of creating a 3D survey photo of the present invention is not only used for earth work management of earth work as described above, but also the output of the structure whose height increases according to the construction of the structure. It is also used for management. The error in managing the volume of the structure is stricter than that of earth work, and should be set to about ± 3 cm.

  As can be understood from the above description, according to the method for creating a three-dimensional survey photograph of the present invention, a UAV equipped with a camera is caused to fly, and a plurality of different plane photographs including a common point are taken from the sky. For each common point, and for each common point, superimpose multiple planar photographs that include the common point while matching the corresponding common points, and 3D information on the construction site based on the 3D information of the reference point By applying the provided method of creating a planar composite photograph, even when using a planar photograph taken by an inexpensive UAV equipped with a camera with a resolution of about 12 million pixels, it is provided for accurate construction management. A 3D survey photo can be created.

It is the schematic diagram explaining the condition which is flying UAV and image | photographing from the sky. FIG. 5 is a plan view in which a surveying area is partitioned in a lattice pattern, showing photographing points (common points) and providing reference points having three-dimensional coordinates. It is the figure explaining the state which piled up several plane photographs, making one common point correspond.

  Hereinafter, an embodiment of a method for creating a three-dimensional survey photograph of the present invention will be described with reference to the drawings. Note that the 3D survey photo shown in the example is applied to earth work management for earthwork, but it is used for managing the volume of structures that increase in height as the structure is built. Of course, may be applied.

(Embodiment of 3D survey photo creation method)
FIG. 1 is a schematic diagram illustrating a situation in which a UAV is flying and shooting from the sky. FIG. 2 divides the survey area into a grid, shows shooting points (common points), and has three-dimensional coordinates. FIG. 3 is a plan view in which a reference point is provided, and FIG. 3 is a diagram illustrating a state in which a plurality of plane photographs are overlaid while matching one common point.

  As shown in FIG. 1, in the method for creating a three-dimensional survey photograph of the present invention, a UAV 10 is caused to fly and a survey photograph creation area A in the earthwork area E is photographed from the sky to obtain a large number of plane photographs (data). .

  In the UAV 10 to be used, a plurality of arm members protrude from the main body 1, a propeller 2 is mounted on each arm member, a battery 5 and a GPS 6 are mounted in the center of the main body 1, and a posture control device 4 is provided below the main body 1 via an attitude control device 4. The camera 3 is attached and the whole is comprised.

  The camera has a resolution of about 12 million pixels and is light, and due to this, the weight of the entire UAV10 body is also light (for example, about 2 kg), and the purchase cost is as low as about 300,000.

  A maximum flight speed of about 10 m / s and a maximum flight altitude of about 150 m can be used.

  The UAV 10 may take a photo of the surveying photo creation area A by controlling the flight altitude h from the ground to about 40 m to fly over the surveying photo creation area A.

  The inventor has specified that the accuracy of the 3D survey photograph that is finally created depends on the flight altitude, and as a result of the verification by the inventor, the flight altitude can create a highly accurate 3D survey photograph. This is because about 40 m is specified.

  As shown in FIG. 1, a plurality of reference points S are set in the survey photo creation area A with a predetermined distance d.

  This reference point has three-dimensional coordinates (x, y, z), and gives a three-dimensional survey photograph by adding three-dimensional information to the finally synthesized planar composite photograph.

  Here, the reference point distance d is preferably set to 100 m or less.

  It has been specified by the present inventor that the distance between the reference points affects the accuracy of the three-dimensional survey photograph. As a result of the verification by the present inventor, the distance d between the reference points capable of creating a highly accurate three-dimensional survey photograph is 100 m. This is due to the fact that:

  Next, on the plane including the reference point S, a method of superimposing a large number of photographed plane photographs while matching common points that are common to each other and developing them in the plane to create a plane composite photograph is illustrated. A description will be given with reference to FIGS.

  In FIG. 2, the reference point S is arranged at a grid point at a distance d, and a large number of common points P are arranged in a large number of cells.

  One planar photograph has a longitudinal length a and a lateral length b, and a planar photograph is formed with nine squares in the figure.

  As shown in FIG. 3, when an arbitrary common point P is noted, a total of nine planar photographs including the common point P can be overlaid. That is, a plane photograph having a common point P in the center, a plane photograph having the upper center, a plane photograph having the lower center, a plane photograph having the upper right section, a plane photograph having the right center, a plane photograph having the lower right section, Similarly, the left row is a plane photograph having the top, center, and bottom.

  In this way, a composite photograph (data) is created by superimposing a plurality of planar photographs (data) so as to match one common point, so that one photograph taken with a camera having a resolution of about 12 million pixels. Although the accuracy of planar photographs is low, the precision of composite photographs is extremely high.

  Then, the operation of creating a composite photograph (data) by superimposing a plurality of plane photographs (data) so as to match one common point in this way is performed at all the common points P shown in FIG. A highly accurate planar composite photograph is created.

  Here, the number of overlapping planar photographs having common points is preferably nine or more.

  It has been specified by the present inventors that the number of overlays of planar photographs affects the accuracy of 3D survey photographs, and as a result of verification by the present inventors, planar photograph overlays that can create highly accurate 3D survey photographs. This is because nine or more sheets are specified.

  In creating an actual 3D survey photo, a large number of plane photos are taken in the sky, then the photos are selected, the selected photo data is uploaded to a computer, and the photo data is imported into the cloud image processing software. By creating point cloud data and performing noise cut processing, a 3D survey photograph (surface model) with 3D information is created.

  According to the method for creating a three-dimensional survey photograph of the present invention, even when using a plane photograph taken by an inexpensive UAV 10 equipped with a camera 3 having a resolution of about 12 million pixels, it is provided for high-precision construction management. It becomes possible to create 3D survey photographs.

(Experiment and results of verifying optimum values of flight altitude of UAV, number of superimposed plane photographs, and distance between reference points)
The inventor conducted experiments to verify the optimum values of the flight height of the UAV, the number of superimposed plane photographs, and the distance between reference points. This experiment was conducted at both N test sites on March 12 and 24, 2015.

  As for UAV flight altitude, three types of flight altitudes of 20m, 40m, and 60m were taken from above, and 3D survey photographs were created based on the plane photographs taken by each. Maximum error was measured.

  In addition, regarding the number of planar photographs to be superimposed, a planar composite photograph (three-dimensional survey photograph) is created for each of the three common points, two, four, and nine. Maximum error was measured.

  Further, regarding the distance between the reference points, three-dimensional survey photographs were prepared with two distances between the reference points of 100 m and 200 m, respectively, and the maximum error of the three-dimensional survey photograph was measured.

  Table 1 shows the experimental results regarding the flight altitude of the UAV, Table 2 shows the experimental results regarding the number of superimposed plane photographs, and Table 3 shows the experimental results regarding the distance between the reference points. In the experimental results, the maximum error in the x and y planes, the maximum error in the height direction z, and the absolute values of their combined components are shown.

  From Table 1, when the flight altitude of UAV is 40m, the absolute value of the maximum error is 0.094m (9.4cm) for No.2 and 10cm or less, and 0.106m (10.6cm) for No.3. It can be seen that the flight height of UAV is preferably 40 m, since the error is much larger than 10 cm, and the allowable error of 10 m is greatly exceeded at 60 m higher than 40 m and 20 m lower than 40 m.

  Also, from Table 2, regarding the number of planar photographs to be superimposed, the absolute value of the maximum error in the case of 9 No. 2 was 0.094 m (9.4 cm) and 10 cm or less. Here, although No. 1 was also nine, the absolute value of the maximum error was 0.205 m (20.5 cm), which greatly exceeded the allowable value because the flight altitude was too high at 60 m.

  Further, in the cases where the number of overlapped sheets was 2 or 4, the absolute value of the maximum error greatly exceeded the allowable error.

  From this result, it can be seen that the number of overlapping sheets is preferably nine.

  Furthermore, from Table 3, regarding the distance between the reference points, the absolute value of the maximum error is 0.094 m (9.4 cm) at 10 m or less for No. 3 of 100 m, and the maximum error for No. 5 of 100 m. The absolute value of was 0.106 m (10.6 cm) and was almost 10 cm. Here, although No. 1 also has a distance between the reference points of 100 m, the absolute value of the maximum error greatly exceeded the allowable value of 0.205 m (20.5 cm) because the flight altitude was too high at 60 m. In No. 7, the distance between the reference points is 100 m, but the flight altitude is too low at 20 m, and the number of plane images to be superimposed is too few, so the absolute value of the maximum error is 0.442 m (44. 2 cm), which was far above the allowable value.

  From this result, it can be seen that the distance between the reference points is preferably 100 m.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Main body, 2 ... Propeller, 3 ... Camera, 4 ... Attitude control device, 5 ... Battery, 6 ... GPS, 10 ... UAV, E ... Earthwork area, A ... Surveying photo creation area, P ... Common point (shooting point) ), S ... reference point, h ... flight altitude

Claims (5)

At the construction site, install multiple reference points with 3D coordinates at predetermined intervals,
A UAV (multi-copter) equipped with a camera is allowed to fly and a plurality of different plane photographs including common points are taken from the sky, and this is performed for each of the plurality of common points.
For each common point, superimpose multiple planar photographs that include common points while matching the corresponding common points, and create a planar composite photograph with 3D information on the construction site based on the 3D information of the reference point. A method for creating a 3D survey photo, which is used as a 3D survey photo.   Using the height of the pressure contact mark generated by the crawler used as a traveling device for leveling equipment used at the construction site as the allowable error, the number of superimposed multiple plane photographs with common points, the distance between adjacent reference points, and flight The method for creating a three-dimensional survey photograph according to claim 1, wherein the altitude and the number of pixels of the camera are set.   The method for creating a three-dimensional survey photograph according to claim 1 or 2, wherein nine or more planar photographs are superimposed in superimposing a plurality of planar photographs having a common point.   The method for creating a three-dimensional survey photograph according to any one of claims 1 to 3, wherein a distance between adjacent reference points is 100 m or less.   The method for creating a three-dimensional survey photograph according to any one of claims 1 to 4, wherein the flight altitude of the UAV is in a range of 40 m ± 4 m.

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