KR102308234B1 - A method for positioning GCP and a device using the same - Google Patents

Abstract

The technical problem to be solved by the present invention is to provide a method for ground control point positioning in an appropriate number and in an appropriate position. The method for ground control point positioning divides DSM data including height information for each of a plurality of positions into a plurality of unit cells, determines a first position as a position of a first ground control point; sets a first virtual area of a first size based on the first position, determines a second position different from the first position as the position of a second ground control point; and sets a second virtual area of a second size based on the second position. A first size is determined based on first height information of the first position, and a second size is determined based on second height information of the second position.

Description

Ground reference point positioning method and apparatus {A method for positioning GCP and a device using the same}

The present invention relates to a ground reference point positioning method and apparatus. Specifically, the present invention relates to a method and apparatus for determining a minimum number of ground reference points or determining an optimal arrangement of ground reference points.

Aerial photography and surveying technology using drones may be difficult to accurately measure due to the limitations of its fundamental technology. To supplement this, it is necessary to install a ground control point (GCP) at the survey site. The ground reference point is a kind of survey point that needs to obtain accurate coordinates using a GPS device. When modeling aerial photography and survey values using drones through three-dimensional reconstruction, a three-dimensional model with greatly improved accuracy can be obtained if the survey value of this ground reference point is used.

However, since installing the ground reference point on the site consumes a lot of manpower and cost, it is considered very important in terms of efficiency to set an appropriate number of ground reference point installation points.

Accordingly, there is a need for a method and apparatus for automatically calculating an appropriate number of ground reference points and an appropriate location for excellently correcting a three-dimensional model according to the range and shape of the area in which drone aerial photography is performed.

The technical problem to be solved by the present invention is to provide a method for positioning ground reference points in an appropriate number and in an appropriate position.

Another technical problem to be solved by the present invention is to provide an apparatus for positioning ground reference points in an appropriate number and in an appropriate position.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

A ground reference point positioning method according to some embodiments of the present invention for achieving the above technical problem divides DSM data including height information for each of a plurality of locations into a plurality of unit cells, and divides the first location of the first ground reference point a position is determined, a first virtual region of a first size is set based on the first position, a second position different from the first position is determined as a position of a second ground reference point, and a second position is determined based on the second position. and setting a second virtual region of the size, wherein the first size is determined based on first height information of the first location, and the second size is determined based on second height information of the second location.

In some embodiments, the location of the ground reference point is repeatedly determined until the plurality of unit cells are all included in at least a part of the accuracy guarantee region, wherein the accuracy guarantee region includes the first and second virtual regions.

In some embodiments, when the first location and the second location are immediately adjacent, the first and second regions at least partially overlap.

In some embodiments, the first and second locations are determined such that the total number of ground reference points including the first and second ground reference points is minimized.

In some embodiments, the first and second positions are determined based on an air path of the aircraft.

In some embodiments, the first location is an edge of the DSM data.

In some embodiments, the first location is one of the vertices of a convex hull of the DSM data.

In some embodiments, the first location is the center of gravity of the convex hull of the DSM data.

In some embodiments, the first location is determined according to Harris corner detection.

A ground reference point positioning device according to some embodiments of the present invention for achieving the above technical problem includes a ground reference point positioning module for determining the position of a ground reference point using DSM data and a storage device in which DSM data is stored, but DSM data includes horizontal position information and height information for horizontal position information, the ground reference point positioning module sets a plurality of regions to include all of the horizontal position information, and the size of each of the plurality of regions is horizontal position information of each of the plurality of regions It is determined based on the height information corresponding to .

The details of other embodiments are included in the detailed description and drawings.

1 is an exemplary view for explaining a ground reference point positioning apparatus according to some embodiments of the present invention.
2 is an exemplary view for explaining a ground reference point positioning method according to some embodiments of the present invention.
3 is an exemplary diagram for describing DSM data according to some embodiments of the present invention.
4 is an exemplary diagram for explaining a process of dividing DSM data into a plurality of unit cells according to some embodiments of the present invention.
5 is an exemplary diagram for explaining determining a first location and setting a first virtual area according to some embodiments of the present disclosure;
6 is an exemplary diagram for explaining determining a second location and setting a second virtual area according to some embodiments of the present disclosure;
7 is an exemplary diagram for explaining determining a third location and setting a third virtual region according to some embodiments of the present disclosure;
FIG. 8 is an exemplary diagram for explaining a process of determining a ground reference point until a plurality of unit cells are all included in a virtual region according to some embodiments of the present invention.
9 is an exemplary view for explaining the position of the ground reference point determined according to the ground reference point positioning method according to some embodiments of the present invention.

Advantages and features of the disclosed embodiments, and methods of achieving them, will become apparent with reference to the embodiments described below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments allow the present disclosure to be complete, and those of ordinary skill in the art to which the present disclosure pertains. It is only provided to fully inform the person of the scope of the invention.

Terms used in this specification will be briefly described, and the disclosed embodiments will be described in detail.

The terms used in this specification are selected as currently widely used general terms as possible while considering the functions in the present disclosure, but may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the terms used in the present disclosure should be defined based on the meaning of the term and the contents of the present disclosure, rather than the simple name of the term.

References in the singular herein include plural expressions unless the context clearly dictates that the singular is singular. Also, the plural expression includes the singular expression unless the context clearly dictates the plural.

When a part "includes" a certain element throughout the specification, this means that other elements may be further included, rather than excluding other elements, unless otherwise stated.

Also, as used herein, the term “module” refers to a software or hardware component, and “module” performs certain roles. However, "module" is not meant to be limited to software or hardware. A “module” may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Thus, by way of example, a “module” includes components such as software components, object-oriented software components, class components and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays and variables. The functionality provided within components and “modules” may be combined into a smaller number of components and “modules” or further divided into additional components and “modules”.

Hereinafter, with reference to the accompanying drawings, embodiments will be described in detail so that those of ordinary skill in the art to which the present disclosure pertains can easily implement them. And in order to clearly describe the present disclosure in the drawings, parts irrelevant to the description will be omitted.

1 is an exemplary view for explaining a ground reference point positioning apparatus according to some embodiments of the present invention.

Referring to FIG. 1 , an apparatus 10 for positioning a ground reference point according to some embodiments may include a processor 100 and a data storage device 200 . The processor 100 may communicate with the data storage device 200 .

The processor 100 may include a general purpose processor, a central processing unit (CPU), a graphics processing unit (GPU), a tensor processing unit (TPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, and the like. should be interpreted broadly. In some circumstances, processor 100 may refer to an application specific semiconductor (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), or the like. The term processor 100 refers to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of a plurality of microprocessors, a combination of one or more microprocessors in combination with a DSP core, or any other such configurations. may refer to

Data storage device 200 should be construed broadly to include any electronic component capable of storing electronic information. The term memory includes random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erase-programmable read-only memory (EPROM), electrical may refer to various types of processor-readable media, such as erasable PROM (EEPROM), flash memory, magnetic or optical data storage, registers, and the like.

The processor 100 may include a ground reference point positioning module 110 . The data storage device 200 may store the DSM data 210 . In this case, the DSM data 210 is digital surface model (DSM) data, and may refer to data produced by measuring the topographic features of the ground surface, the height of trees, and the like. The DSM data 210 may include information on a horizontal position and information on a vertical position. In other words, the DSM data 210 may include position information on the X-Y plane, which is a two-dimensional plane, and height information in the Z direction intersecting the X-Y plane. That is, the DSM data 210 may include information on (x, y, z) coordinates of a three-dimensional coordinate system.

The ground reference point positioning module 110 of the processor 100 may use and process the DSM data 210 stored in the data storage device 200 to determine the optimal number and/or optimal location of the ground reference point.

In this case, a ground control point (GCP) may be a kind of survey point at which an accurate coordinate value must be obtained using a GPS device. The ground reference point may be generated by using a point that can be visually identified in the DSM data 210 or by intentionally marking it. The number and positions of these ground reference points may be a necessary part in the correction step for generating aerial photographing data. That is, even if the aerial photograph is taken to generate an aerial photographed image, if the aerial photograph itself is distorted, the coordinates of the image may be different from the actual coordinates. Therefore, this difference can be corrected through the ground reference point.

Therefore, determining the number and location of such ground reference points is an essential part for precise aerial photographing data generation, and if the arrangement of ground reference points can be confirmed without trial and error, the cost and effort of generating point cloud data can be greatly reduced.

In other words, the ground reference point positioning module 110 may determine the optimal number and/or optimal positions of the ground reference points according to the ground reference point positioning method according to some embodiments of the present invention. The number of ground reference points and/or positions of the ground reference points determined by the ground reference point positioning module 110 may be stored in the data storage device 200 .

2 is an exemplary view for explaining a ground reference point positioning method according to some embodiments of the present invention.

1 and 2 , the ground reference point positioning module 110 may divide the DSM data 210 into a plurality of unit cells (S200). Further reference is made to FIGS. 3 and 4 for an exemplary description.

3 is an exemplary diagram for describing DSM data according to some embodiments of the present invention. 4 is an exemplary diagram for explaining a process of dividing DSM data into a plurality of unit cells according to some embodiments of the present invention. 5 is an exemplary diagram for explaining determining a first location and setting a first virtual area according to some embodiments of the present disclosure; 6 is an exemplary diagram for explaining determining a second location and setting a second virtual area according to some embodiments of the present disclosure; 7 is an exemplary diagram for explaining determining a third location and setting a third virtual region according to some embodiments of the present disclosure; FIG. 8 is an exemplary diagram for explaining a process of determining a ground reference point until a plurality of unit cells are all included in a virtual region according to some embodiments of the present invention. 9 is an exemplary view for explaining the position of the ground reference point determined according to the ground reference point positioning method according to some embodiments of the present invention.

Referring to FIG. 3 , as described above, the DSM data 210 may include information on a horizontal position and information on a vertical position. In other words, the DSM data 210 forms a grid at regular intervals on a two-dimensional plane, and information about (x, y) coordinates at each grid point and height (z) at the corresponding (x, y) coordinates may include.

Referring to FIG. 4 , the ground reference point positioning module 110 may divide the DSM data 210 into a plurality of unit cells C_unit. FIG. 4 shows that one data space is divided into four unit cells (C_unit), but this is an exemplary description and embodiments are not limited thereto. Since the DSM data 210 includes 3D data information, the unit cell C_unit may also include 3D data information. For example, the unit cell C_unit may mean a voxel.

2 and 5 , the ground reference point positioning module 110 may determine the first location BP_1 as the location of the first ground reference point ( S201 ).

The first position BP_1 may refer to a position of a ground reference point that is first determined with reference to the DSM data 210 . The first position BP_1 may be determined through various criteria/strategies. For example, the ground reference point positioning module 110 may select one of the grid points existing at the edge of the DSM data 210 as the first position BP_1.

As another example, the ground reference point positioning module 110 may form a convex hull based on the DSM data 210 and determine one of the vertices of the convex hull as the first position BP_1. In this case, the convex hull means that when there are several points on the dimensional plane, a convex polygon is created using some of the points, but all points are included in the convex polygon.

As another example, the ground reference point positioning module 110 may form a convex hull based on the DSM data 210 and determine the center of gravity of the convex hull as the first position BP_1. When the ground reference point positioning module 110 determines the center of gravity of the convex hull as the first position BP_1, it is possible to minimize the occurrence of a bowl effect, which is likely to occur when the 3D map is reconstructed. For another example, the ground reference point positioning module 110 may determine a corner determined through Harris corner detection in the DSM data 210 as a first position (BP_1). However, these criteria/strategies are illustrative only and the embodiments are not limited thereto. A person of ordinary skill in the art of the present invention may determine the first position BP_1 in various ways in addition to the above-described criteria/strategy.

The ground reference point positioning module 110 may set the first virtual region BR_1 of the first size around the first position BP_1 ( S202 ). The first virtual region BR_1 may be a region in which the accuracy of the first ground reference point is guaranteed. In other words, since the first ground reference point is installed at the first position BP_1 , accuracy as much as the first virtual region BR_1 with respect to the first position BP_1 may be guaranteed. The first virtual region BR_1 may have a first size. The first size may be determined according to height information of the first position BP_1. In other words, the first size of the first virtual region BR_1 may be determined according to the height of the first position BP_1 at which the first ground reference point is installed. In other words, the first size of the first virtual area BR_1 may be determined according to the height of the center of the first virtual area BR_1 .

2 and 6 , the ground reference point positioning module 110 may determine the second location BP_2 as the location of the second ground reference point ( S203 ). Similarly, the second location BP_2 may be selected through various criteria/strategies. For example, the ground reference point positioning module 110 may determine one of the grid points existing at the edge of the DSM data 210 as the second position BP_2. As another example, the ground reference point positioning module 110 may form a convex hull based on the DSM data 210 and determine one of the vertices of the convex hull as the second position BP_2. As another example, the ground reference point positioning module 110 may determine the second position BP_2 of the corner determined through Harris corner detection in the DSM data 210 . However, these criteria/strategies are illustrative only and the embodiments are not limited thereto. A person skilled in the art of the present invention may determine the second position BP_2 in various ways in addition to the above-described criteria/strategy.

The ground reference point positioning module 110 may set the second virtual region BR_2 of the second size centered on the second position BP_2 ( S204 ). The second virtual region BR_2 may be a region in which the accuracy of the second ground reference point is guaranteed. In other words, since the second ground reference point is installed at the second position BP_2 , the accuracy as much as the second virtual region BR_2 may be guaranteed.

The second virtual region BR_2 may have a second size. The second size may be determined according to height information of the second location BP_2. In other words, the second size of the second virtual area BR_2 may be determined according to the height of the second location BP_2 where the second ground reference point is installed.

The ground reference point positioning module 110 may repeatedly perform the above process until all of the plurality of unit cells C_unit are included in the set virtual area (S205). In other words, the ground reference point positioning module 110 determines the location of the ground reference point, determines the size of the virtual area according to the height corresponding to the location of the ground reference point, and sets the virtual area of the determined size based on the location. can be done repeatedly. This process may be repeated until all of the plurality of unit cells (C_unit) are included in the set virtual region. For exemplary description, it will be described with reference to FIGS. 7 to 9 .

Referring to FIGS. 2 and 7 , similarly to the previous process, the ground reference point positioning module 110 may determine the third position BP_3 as the location of the third ground reference point. The third location BP_3 may be selected through various criteria/strategies. The ground reference point positioning module 110 may set the third virtual region BR_3 of the third size around the third position BP_3 . The third virtual region BR_3 may be a region in which the accuracy of the third ground reference point is guaranteed. In other words, since the third ground reference point is installed at the third position BP_3 , the accuracy as much as the third virtual region BR_3 may be guaranteed. The third virtual region BR_3 may have a third size. The third size may be determined according to height information of the third location BP_3. In other words, the third size of the third virtual region BR_3 may be determined according to the height of the third location BP_3 where the third ground reference point is installed.

8 and 9 , the ground reference point positioning module 110 may determine the location of the ground reference point until all of the plurality of unit cells C_unit are included in the virtual area. In the plurality of virtual regions, the center of each virtual region becomes the position of the ground reference point.

According to some embodiments, in the case of two ground reference points disposed immediately adjacent to each other, the virtual region of each ground reference point may include a portion overlapping each other.

3 to 9 are merely exemplary descriptions, and embodiments are not limited thereto.

According to some embodiments, the ground reference point positioning apparatus 10 may position the ground reference point in various strategies as needed. For example, the ground reference point positioning apparatus 10 may position the ground reference point to use the minimum number of ground reference points under a condition that all of the plurality of unit cells C_unit are included in the virtual region. For another example, the ground reference point positioning apparatus 10 may determine the arrangement of the ground reference point based on the air path of an aircraft such as a drone under a condition that all of the plurality of unit cells C_unit are included in the virtual area. In other words, the ground reference point positioning device 10 determines the arrangement of the ground reference points with reference to the flight path of an aircraft such as a drone obtained in advance, but the number and arrangement can be determined.

As another example, the distance between the ground reference points for obtaining the desired accuracy of the ground reference points may be set as the radius of the virtual area. And, by modeling the accuracy of the height in the form of a Gaussian distribution, it is possible to obtain a height threshold of a desired size. A virtual region may be set based on the obtained values, and the ground reference point may be positioned such that a plurality of unit cells are all included in the virtual region.

Through this, the present embodiment can secure more precise aerial photographing data through the number and location of ground reference points that can produce the best efficiency. Although the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above embodiments and may be manufactured in a variety of different forms, and those skilled in the art to which the present invention pertains can implement in other specific forms without changing the technical spirit or essential features of the present invention You will understand that it can be Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (10)

DSM data including height information for each of a plurality of positions is divided into a plurality of unit cells,
determining the first position as the position of the first ground reference point;
setting a first virtual region of a first size with respect to the first position;
determining a second position different from the first position as a position of a second ground reference point;
and setting a second virtual region of a second size based on the second location,
The first size is determined based on first height information of the first location,
The second size is a ground reference point positioning method determined based on the second height information of the second position.
According to claim 1,
The position of the ground reference point is repeatedly determined until the plurality of unit cells are all included in at least a part of the accuracy guarantee area, wherein the accuracy guarantee area includes the first and second virtual areas.
According to claim 1,
When the first position and the second position are directly adjacent to each other, the first and second regions partially overlap a ground reference point positioning method.
According to claim 1,
The first and second positions are determined such that the total number of ground reference points including the first and second ground reference points is minimized.
According to claim 1,
The first and second positions are a ground reference point positioning method that is determined based on the air path of the aircraft.
According to claim 1,
The first position is the edge of the DSM data ground reference point positioning method.
According to claim 1,
The first position is one of the vertices of a convex hull of the DSM data.
According to claim 1,
The first position is a ground reference point positioning method that is a center of gravity of a convex hull of the DSM data.
According to claim 1,
The first position is a ground reference point positioning method determined according to a Harris corner detection (Harris corner detection).
a ground reference point positioning module for determining the location of a ground reference point using DSM data; and
A storage device in which the DSM data is stored,
The DSM data includes horizontal position information and height information for the horizontal position information,
The ground reference point positioning module sets a plurality of areas to include all of the horizontal position information, and the size of each of the plurality of areas is a ground reference point determined based on height information corresponding to the horizontal position information of each of the plurality of areas. positioning device.

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