Three-dimensional flight route creation method

Abstract

To provide a three-dimensional flight route creation method for allowing a flying body, particularly a UAV (Unmanned Aerial Vehicle), which is a so-called drone, to fly under automatic control in order to solve problems in manual control.SOLUTION: A flight route creation method of creating a flight route of a flying body which flies under automatic control through remote control and automatically images an object of imaging includes a step of creating a separation mesh having a predetermined separation distance with respect to a structure mesh of the object of imaging, a step of creating a flight line, which represents a route along which the flying body flies, on the created separation mesh, and a step of creating a WP corresponding to a point where the object of imaging is imaged on the created flight line.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a three-dimensional flight path generation method and program. [Background technology]

[0002] There is a need to photograph large three-dimensional objects such as dams and bridges from an aerial vehicle to inspect their surface structure, defects, etc. Drones are used for such photography. Inspecting surface structures, defects, etc. requires high-resolution, consistent quality photography without omission, so multiple (many) photos must be taken. This requires the drone to fly a specified route and take photos at specified intervals.

[0003] However, when taking such photographs, the drone must be flown along a specified path while maintaining a specified distance from three-dimensional objects with complex surface structures, and taking photographs at specified intervals along such a flight path is extremely difficult to control manually. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-43543 [Non-patent literature]

[0005] [Non-Patent Document 1] Taubin, “Curve and surface smoothing without shrinkage”, 1995 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, in order to solve the problems with manual control described above, the present invention aims to provide a three-dimensional flight path creation method and program for automatically controlling the flight of an aircraft, particularly a UAV (Unmanned Aerial Vehicle), a so-called drone, etc. [Means for solving the problem]

[0007] This problem is solved by a flight path creation method according to the present invention, which is a method for creating a flight path for an aircraft that automatically photographs a subject while flying under automatic control by remote control, and which includes the steps of creating a separation mesh with a predetermined separation distance from the structural mesh of the subject, creating a flight line on the created separation mesh that is the path the aircraft will fly along, and creating a WP (waypoint) on the created flight line that corresponds to the point from which the subject will be photographed.

[0008] In a further development, in the step of creating a discrete mesh, a normal may be estimated for each mesh point, and after the normal estimation, a discrete mesh may be created in the direction of the estimated normal.

[0009] Advantageously, smoothing is performed during the step of creating the discrete mesh.

[0010] In the step of creating a flight line, a plurality of flight lines may be determined, and the flight lines may be determined by convergence calculation so that the average interval between the plurality of flight lines is constant.

[0011] Furthermore, in the step of creating a WP, when determining the next WP, it is also possible to determine the position of a predetermined segment of the flight line. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a conceptual diagram of a flight path created by a flight path creation method according to the present invention. [Figure 2] Flowchart of the flight path creation method according to the present invention [Figure 3] Diagram of how the surface of the subject is extracted from 3D point cloud data [Figure 4] 1 is a diagram showing how mesh transformation is performed according to the method of the present invention; [Figure 5] 1 is a diagram showing how a separate mesh is created according to the method of the present invention. [Figure 6] 1 is a diagram showing how a flight line is created according to the method of the present invention. [Figure 7] A diagram showing how a WP is created according to the method of the present invention. [Figure 8] Editing the created WP [Figure 9] 1 is a diagram showing the configuration of hardware for implementing a flight path generation program according to the present invention. [Figure 10] 1 is a flowchart of a mesh transformation step in a method according to the present invention. [Figure 11] Flowchart of the step of creating a separate mesh in the method according to the present invention [Figure 12] Illustration of substeps during the separation meshing step [Figure 13] Illustration of substeps during the separation meshing step [Figure 14] Illustration of substeps during the separation meshing step [Figure 15] Illustration of substeps during the separation meshing step [Figure 16] Illustration of substeps during the separation meshing step [Figure 17] Illustration of substeps during the separation meshing step [Figure 18] Illustration of substeps during the separation meshing step [Figure 19] Illustration of substeps during the separation meshing step [Figure 20] Illustration of substeps during the separation meshing step [Figure 21] Illustration of substeps during the separation meshing step [Figure 22] Illustration of substeps during the separation meshing step [Figure 23] Flowchart of the flight line creation step in the method etc. according to the present invention [Figure 24] Illustration of substeps during the flight line creation step [Figure 25] Illustration of substeps during the flight line creation step [Figure 26] Illustration of substeps during the flight line creation step [Figure 27] Illustration of substeps during the flight line creation step [Figure 28] Illustration of substeps during the flight line creation step [Figure 29] Illustration of substeps during the flight line creation step [Figure 30] Illustration of substeps during the flight line creation step [Figure 31] Illustration of substeps during the flight line creation step [Figure 32] Illustration of substeps during the flight line creation step [Figure 33] Illustration of substeps during the flight line creation step [Figure 34] Illustration of substeps during the flight line creation step [Figure 35] Illustration of substeps during the flight line creation step [Figure 36] Illustration of substeps during the flight line creation step [Figure 37] Illustration of substeps during the flight line creation step [Figure 38] Illustration of substeps during the flight line creation step [Figure 39] Illustration of substeps during the flight line creation step [Figure 40] Flowchart of the WP creation step in the method etc. according to the present invention [Figure 41] Diagram of sub-steps in the WP creation process [Figure 42] Diagram of sub-steps in the WP creation process [Figure 43]Diagram of sub-steps in the WP creation process [Figure 44] Diagram of sub-steps in the WP creation process DETAILED DESCRIPTION OF THE INVENTION

[0013] [overview] The present invention will be described in detail below with reference to the embodiments shown in the drawings. First, an overview of the method according to the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 is a diagram showing an aircraft flying a flight path created according to a three-dimensional flight path creation method according to the present invention. In this embodiment, the aircraft is a drone, or UAV (Unmanned Aerial Vehicle). The UAV flies along the created flight path to photograph the surface of a dam, a three-dimensional structure. Although not shown in FIG. 1, the UAV takes photographs a predetermined number of times while flying along this flight path. As can be seen in FIG. 1, the flight path according to the present invention is created in the shape of a square wave or rectangular wave.

[0014] 2 is a flowchart showing the steps performed by the three-dimensional flight path generation method of the present invention. In the three-dimensional flight path generation method of the present invention, steps S1 to S3 are performed, and the three-dimensional flight path generation program of the present invention is configured to be able to perform steps S1 to S3. An optional additional WP editing step can also be provided. The WP editing step is not essential.

[0015] In the three-dimensional flight path generation method according to the present invention, three-dimensional point cloud data (raw data) is first acquired in the preliminary and preparatory stages, as shown in Fig. 2. Three-dimensional point cloud data is a set of data of points that represent the three-dimensional positions of objects, and such three-dimensional point cloud data can be acquired by methods such as LiDAR measurement or photogrammetry.

[0016] In the preliminary and preparatory stages of the method of the present invention, following the acquisition of three-dimensional point cloud data, the target range is extracted. The target range refers to the area or surface to be photographed, i.e., extracting the target range means extracting the area, range, or surface (the area to be photographed, the surface to be photographed) of a three-dimensional structure that is to be photographed. The process of extracting the surface to be photographed is schematically shown in FIG. 3. As shown in FIG. 3, in this step, point cloud data of the area to be photographed, i.e., point cloud data of the area of ​​the structure to be photographed, is extracted from the acquired three-dimensional point cloud data. Extraction of the surface to be photographed can also be performed using general software.

[0017] Following the extraction of the target range, the extracted 3D point cloud is subjected to mesh conversion. The mesh conversion process is shown schematically in Figure 4. By performing mesh conversion, a structure mesh, i.e., 3D data of the structure being photographed, is created from the 3D point cloud. Note that in this example, a method of performing mesh conversion from a 3D point cloud to create a structure mesh has been described as an example, but the structure mesh can also be created by generating a 3D shape using photogrammetry (SfM) or by performing mesh conversion from CAD data.

[0018] Following the mesh conversion, a separate mesh is created relative to the created structure mesh in accordance with the three-dimensional flight path creation method of the present invention. The process of creating a separate mesh is shown schematically in Fig. 5. As can be seen in Fig. 5, a separate mesh is a mesh that has a predetermined distance (spacing) from the structure mesh. In this example, a separate mesh that has a 5 m separation from the structure mesh is created.

[0019] After creating the separation mesh, the three-dimensional flight path creation method of the present invention creates flight lines, i.e., flight paths, on the created separation mesh. The creation of flight lines and flight paths is schematically shown in FIG. 6. The flight lines are formed in the shape of equally spaced square or rectangular waves, as shown in FIG. 6. In this embodiment, the distance between adjacent flight lines (flight line distance) is represented as d2. The flight line distance d2 is determined taking into account the side-lap ratio (overlap), separation distance, camera FOV (field of view), and the like. In the example shown in FIG. 6, the flight lines are created starting from the flight starting point at the bottom left of the figure, extending to the right, and when they reach the right edge of the target surface (target area), they are offset by the flight line distance d2, and then extending toward the left edge of the target surface (target area). When it reaches the left edge of the target surface (target area), it is again offset by the flight line distance d2 and extends again towards the right edge, and so on, forming square wave and rectangular wave shapes in sequence.

[0020] Following the creation of the flight line, the three-dimensional flight path creation method of the present invention creates waypoints (WPs). The waypoint creation process is shown schematically in FIG. 7. Waypoints are created on the flight line at shooting intervals d1, as shown in FIG. 7. d1 is determined taking into consideration factors such as the overlap rate, separation distance, and camera FOV (field of view). In this embodiment, as shown in FIG. 7, waypoints are first created at the flight start point, then at shooting intervals d1, and so on, moving sequentially to the right in the diagram. When the right edge of the plane being photographed is reached, a waypoint is created at the right edge of the diagram on the next flight line, offset by flight line interval d2. Then, waypoints are created sequentially to the left at shooting intervals d1.

[0021] Once creation of waypoints on all flight lines has been completed in this manner, the three-dimensional flight path generation method of the present invention performs waypoint editing. Waypoint editing is schematically shown in Figure 8. During waypoint editing, meshes (structure mesh, separation mesh) and waypoints are displayed in 3D on the output device of the three-dimensional flight path generation system of the present invention, and are configured to be editable. As shown in the figure, editing can be configured to be enabled on the output device of the three-dimensional flight path generation system.

[0022] 9 shows the hardware configuration of a computer for implementing the above-described three-dimensional path generation method according to the present invention as a program. This computer has a general hardware configuration for implementing a program, as shown in FIG.

[0023] [Mesh conversion step details] The mesh conversion method will be briefly explained with reference to Fig. 10. Fig. 10 shows an example of a flowchart of each sub-step performed in the mesh conversion step. Mesh conversion can be performed by performing such sub-steps.

[0024] [Details on creating a separate mesh] Next, the creation of a remote mesh according to the method of the present invention will be described. The creation of a remote mesh is performed according to the steps shown in FIG. 11. Specifically, once the structure mesh described above is created, the structure data is loaded. Once loading is complete, coordinate transformation S1-1 is performed on the loaded structure mesh data. Once coordinate transformation S1-1 is complete, normals are estimated S1-2 for each mesh point. After normal estimation S1-2, a mesh is created in the normal direction S1-3. Once creation of the remote mesh S1-3 is complete, mesh smoothing S1-4 is performed, and after smoothing S1-4 is performed, the coordinate system is restored to its original state S1-5, completing step S1 of creating the remote mesh.

[0025] The coordinate transformation S1-1 is performed in three steps as shown in Figures 12 to 14. In the first step of the coordinate transformation, a rectangular parallelepiped with the minimum volume that can contain all the points is found as shown in Figure 12.

[0026] Once the rectangular parallelepiped has been determined, the X, Y, and Z coordinate axes are then determined according to Figure 13. The X, Y, and Z axes are determined so that the lengths a, b, and c of the sides of the bounding box are the x, y, and z axes, respectively, in order of length. In the example of Figure 13, the lengths of the sides are a>b>c, so the a direction is determined to be the x axis, the b direction is the y axis, and the c direction is the z axis. As a result, the original coordinate axes are determined to be the x', y', and z' axes after transformation.

[0027] Once the coordinate axes have been defined, the next step in the coordinate transformation is to perform a coordinate transformation on each point cloud. The coordinate transformation on the point cloud is performed in three steps. First, the entire box is translated so that the center of the box is the origin. Once the translation is complete, the z-axis is rotated so that the z-axis direction matches the direction of the shortest side of the box. Once the z-axis adjustment is complete, the y-axis is then rotated so that the y-axis direction matches the direction of the mid-side of the box (the side with the middle length). This assigns coordinates to each point cloud on the newly transformed coordinate axes.

[0028] In the next step, normals for each point are estimated (S1-2). Normal estimation (S1-2) is performed in three steps as shown in Figures 15 to 17. In the first step of normal estimation, as shown in Figure 15, a sphere of radius r2 is set with the target point as its center, and points within this sphere are set as neighboring points. Next, principal component analysis is performed on neighboring points including the target point, and of the three eigenvectors obtained by the principal component analysis, the vector with the smallest eigenvalue is determined as the normal direction (Figure 16). In the next step of normal estimation, the normal direction is determined to be unidirectional when viewed from a certain position. Since the normal direction can be positive or negative, a point dz(m) away from the center of the bounding box in the z-axis direction is set, and adjustments are made so that all normal directions are unidirectional when viewed from that point (Figure 17).

[0029] Step S1-3 for creating a distant mesh in the normal direction will now be described. The distant mesh is created by creating a mesh that is moved a distance D in the normal direction from each mesh point. Since a normal vector is defined for each mesh point of the structure mesh according to the above steps, the distant mesh is created by moving to a point that is a distance D in the normal direction from each mesh point of the structure mesh, as shown in Figure 18.

[0030] In the next step, mesh smoothing S1-4 is performed. This is to minimize small irregularities in the mesh by smoothing. Mesh smoothing can be performed, for example, by Taubin's method described in Non-Patent Document 1 (FIG. 19). This method is a smoothing method that does not reduce the volume of the mesh. Taubin's method is described in detail in Non-Patent Document 1, so it will not be described in detail here.

[0031] Smoothing can also be performed using an averaging filter (Fig. 20). In this method, for a mesh point T, the average T' of the mesh point T and its m neighboring points Ni is first calculated. T' is calculated according to the formula shown in Fig. 20. This averaging is performed for all mesh points to smooth the mesh (Fig. 20).

[0032] Smoothing can also be performed using a Laplacian filter (Fig. 21). The Laplacian filter method differs from the averaging filter method described above in that a mesh point T is weighted by Wi, which is the inverse of the distance between adjacent points, and filtered according to a filter strength λ set by the user (Fig. 21).

[0033] Once the smoothing step S1-4 is complete, the final step of the mesh transformation is the process of restoring the coordinate axes to their original state in S1-5. This process is the reverse of the coordinate transformation performed as the first step of the mesh transformation. This returns the coordinate axes to their original state (Figure 22).

[0034] [Details on creating flight lines] Once the separation mesh has been created, the method of the present invention then proceeds to create a flight line. The flight line is created through the steps shown in Figure 23. Each step will be described in detail below.

[0035] Specifically, the flight line creation step begins with the step of reading in the separation mesh data, followed by the coordinate conversion step S2-1, the step S2-2 of drawing the first flight line F1, followed by the loop L2-1 which is repeated until no more flight lines can be drawn, and the loop L2-2 of drawing the next flight line, after which the coordinate system is restored and the flight line data is output to complete the process.

[0036] As shown in FIG. 23, the loop L2-2 for drawing the next flight line is configured to be repeated within the loop L2-1 which is repeated until no more flight lines can be drawn.

[0037] In the loop L2-2 for drawing the next flight line, there is step S2-3 for drawing a tentative flight line F', a step for determining whether the tentative flight line can be drawn, and a step for determining the distance between the previous flight line and the tentative flight line.

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[0038] As shown in Figure 23, in the loop L2-2 to draw the next flight line, the distance

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[0039] In the step of determining whether a provisional flight line can be drawn in loop L2-1, which is repeated until a flight line can no longer be drawn, if it is determined that a provisional step can no longer be drawn, loop L2-1 ends, the coordinate system is restored, flight line data is output, and step S2 of creating the flight line ends (Figure 23).

[0040] Each sub-step in the flight line creation step S2 will be explained in detail below. First, the coordinate transformation sub-step S2-1 will be explained. The purpose of performing the coordinate transformation sub-step S2-1 is to facilitate the calculation of the flight line by the coordinate transformation. In the coordinate transformation sub-step S2-1, five stages of processing are performed. First, the average normal vector of the separated meshes is calculated. The average normal vector

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[0041] average normal vector

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[0042] Once the mesh rotation is complete, a bounding box is generated along the axis (Figure 27). The bounding box is generated by finding a rectangular parallelepiped that fits all the points along the rotated axis. Then, a translation is performed to align the origin with the minimum position of the bounding box (Figure 28). This completes coordinate transformation substep S2-1.

[0043] After the coordinate transformation substep S2-1, step S2-2 is performed to draw the first flight line F1. As the first flight line F1, a polygonal line is calculated where the mesh intersects with a plane (plane y=f) offset from the bounding box by an offset f [m] (user setting) in the y-axis direction, as shown in Figure 29 (Figure 29).

[0044] Once step S2-2 of drawing the first flight line F1 is completed, as described above, loop L2-1 is repeated until no more flight lines can be drawn, and loop L2-2 is performed to draw the next flight line.However, during these loops, step S2-3 of drawing a tentative flight line F' is first performed.

[0045] In step S2-3 (Figure 30) of drawing a tentative flight line F', a plane offset by dy [m] in the y direction from the previously drawn flight line Fi is calculated, and a broken line where the mesh intersects with the plane is calculated, and the tentative flight line F' is drawn. The initial value of the offset dy [m] is set to d2. If the plane y = yi + dy falls outside the bounding box and the tentative flight line can no longer be drawn (if the plane y no longer intersects with the mesh), as described above, the result of the step of determining whether a tentative flight line can be drawn is No. Then, loop L2-2 for drawing the next flight line and loop L2-1, which is repeated until the flight line can no longer be drawn, end, i.e., the flight line calculation ends.

[0046] In the next step S2-4 (Figure 31), the distance between the previous flight line and the tentative flight line created based on it is calculated. This distance is calculated using a five-step process. To calculate the distance, the number of points on each flight line (broken line) is first confirmed and compared, and the flight line with the most points (number of points) is defined as Ft, and the flight line with the fewest points is defined as Fs. The average distance from Fs to Ft is then calculated.

[0047] Next, point Tj on the flight line Ft whose x coordinate is closest to point Si on the flight line Fs is searched for (Figure 32). This search is performed for all points on the flight line Fs, and the difference in x coordinate between point Si and all points on the flight line Ft is calculated, and point Tj with the smallest difference is searched for.

[0048] Then, the line segment LT closest to point Si is determined as shown in Figure 33. When determining the line segment LT, if the x coordinate of point Tj is greater than that of point Si, the line segment connecting point Tj-1 and point Tj is determined as LT. If the x coordinate of point Tj is smaller than that of point Si, the line segment connecting point Tj and Tj+1 is determined as LT.

[0049] Next, the distance di between the line segment LT and the point Si is calculated (Figure 34). These calculations are performed for all points on the flight line Fs, that is, the distance di at each point Si (i = 1-n) on the flight line Fs is calculated, and the average distance

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[0050] In step S2-4, the calculation of the distance between the immediately preceding flight line and the tentative flight line created based on it can also be performed as follows (Figures 31, 36 to 38, 35) instead of the method described above. First, as in the method described above, the number of points on each flight line (broken line) is confirmed and compared to calculate the distance. The flight line with the most points (number of points) is defined as Ft, and the flight line with the fewest points is defined as Fs (Figure 31). Then, the average distance from Fs to Ft is calculated.

[0051] In this method, next, a search is made for point Tj on the flight line Ft that is the shortest distance from point Si on the flight line Fs (Figure 36). This search is performed for all points on the flight line Ft, and the distance from point Si is calculated to search for point Tj that is the shortest.

[0052] Next, a line segment LT for point Si is determined. The line segment LT is determined as shown in FIG. 37 as follows: (1) if angle Tj-1SiTj≦90°, the line segment connecting point Tj-1 and point Tj is determined as the line segment LT; or (2) if angle TjSiTj+1≦90°, the line segment connecting point Tj and point Tj+1 is determined as the line segment LT. Then, the distance di between line segment LT and point Si is calculated (FIG. 38). Here, (3) if neither (1) nor (2) above applies, the distance di of line segment TjSi is adopted as di, and the calculation of distance di as shown in FIG. 38 is not performed.

[0053] This calculation is performed for all points on the flight line Fs, that is, the distance dj at each point Si (i = 1-n) on the flight line Fs is calculated, and the average distance

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[0054] Next, in step S2-5, which calculates the y-difference dy for drawing a tentative flight line, the difference dy in the y-axis direction for drawing the next tentative flight line is calculated. The difference dy is calculated as shown in Figure 39. In other words, the difference dy is calculated by calculating dy' so that the distance between the next tentative flight line F" and the created flight line Fi is d2.

[0055] In this way, flight lines are determined through convergence calculations so that the average distance between them is constant. Even if a tentative flight line is drawn on a cross section d2 in the y direction, the average distance between the two flight lines (the established flight line and the tentative flight line) is not necessarily d2; it is usually greater than this, so a flight line with an average distance of d2 is searched for through convergence calculations.

[0056] [WP Creation Details] After the flight line is created in step S2, step S3 of creating a WP (WayPoint) is performed. The WP creation step S3 is performed using the substeps shown in Figure 40. These substeps mainly include substep S3-1, which sets the starting point of the flight line as the first WP, loop L3-2 at point Lj on the flight line, and three steps included in loop L3-2: step S3-2, which calculates the distance D between the previous WP and point Lj, step S3-3, which determines whether the calculated D is greater than d1, and if D > d1, step S3-3, which determines the next WP that is d1 away. Finally, step S3-4, which sets the end point of the flight line, which is performed after loop L3-2, as the final WP, is configured to be looped by loop L3-1 as many times as the number of flight lines (Figure 40).

[0057] Each step loop will be described in detail below. First, in substep S3-1, where the starting point of a flight line is the first WP, the starting point of each flight line is determined and the first WP for each flight line is defined as WP = P0, in a manner in which the aircraft flies back and forth while repeatedly offsetting, like flying with a mop, as shown in Figure 41. In Figure 41, the point to the left of the flight line F1 shown at the bottom is determined as the starting point and defined as P0. Then, the point to the right of the offset flight line F2 is determined as the starting point and defined as P0 again. Similar processing is repeated for flight lines F3, F4, and F5, in order.

[0058] After completion of substep S3-1, which sets the start point of the flight line as the first WP, loop L3-2 is started at point Lj on the flight line, as shown in Figure 40. In this loop L3-2, first, substep S3-2 is executed to calculate the distance D between the previous WP and point Lj. In this substep S3-2, the distance D from point Lj on the flight line to the previous WP is calculated, as shown in Figure 42.

[0059] After this substep S3-2 is performed, a subsequent determination step determines whether the calculated distance D is greater than d1 (photographing interval). If it is determined that the calculated distance D is not greater than d1, the process returns to the step shown in Figure 40, and for the next point Lj+1 on the flight line, substep S3-2 is performed to calculate the distance D between the previous WP and point Lj+1. Again, a step is performed to determine whether the calculated D is greater than d1, and substep S3-2 is repeated for points on the flight line until D>d1.

[0060] Once the point where D>d1 is determined, substep S3-3 is performed to determine the next WP d1 away. In this substep, the coordinates of the next WP Pi+1, d1 away from Pi, are calculated. As shown in FIG. 43, a line segment Lj-1Lj is established, consisting of the first point Lj where the distance D is greater than d1 and the previous point Lj-1, and the coordinates of point Pi+1 on this line segment Lj-1Lj are calculated so that the distance between Pi and point Pi+1 is d1. The coordinates of Pi+1 are calculated by solving a quadratic equation for w obtained from the distance formula and finding a solution such that w>0. Thus, in the WP generation step of the method of the present invention, a specific line segment on the flight line is established, and the position within this line segment, the distance from the previous WP being d1, is determined, thereby determining the next WP whose distance is exactly d1.

[0061] Once the WP is determined, substep S3-4 is performed, where the end point of each flight line is set as the last WP, regardless of the distance from the previous WP (Figure 44).

Claims

1. A method for creating a flight path for an aircraft that flies under automatic remote control and automatically photographs a subject, the flight path creation method comprising the steps of: creating a separation mesh with a predetermined separation distance from the structural mesh of the subject; creating a flight line on the created separation mesh that is the path the aircraft will fly; and creating a WP on the created flight line that corresponds to the point from which the subject will be photographed.

2. 2. The flight path generation method according to claim 1, wherein in the step of generating the separated meshes, a normal is estimated for each mesh point, and after the normal is estimated, the separated meshes are generated in the direction of the estimated normal.

3. 3. The method for generating a flight path according to claim 2, wherein smoothing is performed in the step of generating the separated mesh.

4. 2. The flight path generation method according to claim 1, wherein in the step of generating flight lines, a plurality of flight lines are determined, and the flight lines are determined by convergence calculation so that the average interval between the plurality of flight lines is constant.

5. The flight path generation method according to claim 1, characterized in that in the step of generating a WP, when determining the next WP, the position of a predetermined segment of the flight line is obtained, thereby determining the next WP that is a predetermined distance away.

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