阅读说明：本技术 一种机载激光点云航摄漏洞检测方法及系统 (Airborne laser point cloud aerial photography vulnerability detection method and system ) 是由 李冲 李昊霖 佘毅 王辉 于 2020-06-23 设计创作，主要内容包括：本发明公开了一种机载激光点云航摄漏洞检测方法及系统。该机载激光点云航摄漏洞检测方法包括：获取机载激光点云数据集和对应的时间信息；基于机载激光点云数据集提取机载激光点云航带的边界点集；计算机载激光点云航带的宽度；基于机载激光点云航带的边界点集、机载激光点云航带的宽度和航带边界点对集,采用等比例法或整体法进行内缩处理,得到各机载激光点云航带的有效覆盖区域；将航带有效覆盖区域与测区范围进行叠加对比,确定测区范围内是否存在相对漏洞；基于机载激光点云数据集,采用格网法确定测区范围内是否存在绝对漏洞。本发明能够提高漏洞检测的效率和可靠性。(The invention discloses an airborne laser point cloud aerial photography vulnerability detection method and system. The airborne laser point cloud aerial photography vulnerability detection method comprises the following steps: acquiring an airborne laser point cloud data set and corresponding time information; extracting a boundary point set of the airborne laser point cloud navigation band based on the airborne laser point cloud data set; calculating the width of the airborne laser point cloud navigation band; performing retraction processing by adopting an equal proportion method or an integral method based on a boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and a flight band boundary point pair set to obtain an effective coverage area of each airborne laser point cloud flight band; overlapping and comparing the effective coverage area of the flight band with the measuring area range to determine whether a relative bug exists in the measuring area range; and determining whether absolute leaks exist in the measuring area range by adopting a grid method based on the airborne laser point cloud data set. The invention can improve the efficiency and reliability of vulnerability detection.)

1. An airborne laser point cloud aerial photography vulnerability detection method is characterized by comprising the following steps:

acquiring an airborne laser point cloud data set and corresponding time information;

extracting a boundary point set of an airborne laser point cloud navigation band based on the airborne laser point cloud data set;

screening a zone boundary point pair set according to the time information and the boundary point set of the airborne laser point cloud flight band, and calculating the width of the airborne laser point cloud flight band;

performing retraction processing by adopting an equal proportion method or an integral method based on the boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and the flight band boundary point pair set to obtain an effective coverage area of each airborne laser point cloud flight band;

overlapping and comparing the effective coverage area of the flight band with a survey area range, and determining whether a relative bug exists in the survey area range;

and determining whether absolute holes exist in the measuring area range or not by adopting a grid method based on the airborne laser point cloud data set.

2. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 1, wherein the step of overlapping the effective coverage area of the aerial zone with a survey area range to determine whether the survey area range has a relative vulnerability specifically comprises the steps of:

combining the effective coverage areas of all airborne laser point cloud flight strips to obtain a union set of the effective coverage areas;

expanding the measuring area range to obtain an expanded measuring area range;

superposing and comparing the expanded measuring area range and the effective coverage area union set, and judging whether an area which is not covered by the effective coverage area exists in the expanded measuring area range to obtain a first judgment result;

if the first judgment result is yes, a relative bug exists, and the area which is not covered by the effective coverage area in the expanded measurement area range is determined as a relative bug area;

and if the first judgment result is negative, no relative bug exists.

3. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 1, wherein the step of determining whether an absolute vulnerability exists in the survey area range by adopting a grid method based on the airborne laser point cloud data set specifically comprises the following steps:

splicing and fusing the airborne laser point cloud data set to obtain survey area laser point cloud data;

generating an empty raster data set with zero raster values according to set grid intervals on the basis of the laser point cloud data of the survey area;

counting the number of laser points in each grid, and assigning a value to the empty grid data set according to the number of the laser points to obtain a point cloud density map of the survey area;

expanding the measuring area range to obtain an expanded measuring area range;

and setting zero-value pixels in the point cloud density map of the measured area as invalid values, and performing visual superposition comparison on the point cloud density map of the measured area and the expanded measured area range to determine whether an absolute leak exists in the measured area range.

4. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 2 or 3, wherein the step of expanding the range of the measurement area to obtain the expanded range of the measurement area specifically comprises the following steps:

using a formulaCalculating an external expansion value of the measuring area range; wherein e is the extension value of the measuring region range, T_AThe distance beyond the measuring area is required for the effective coverage area of the laser point cloud, B^jThe buffer value of the jth strip laser-carried point cloud navigation band is obtained by adopting an equal proportion method or an integral method for retraction processing;

and expanding the measuring area range by the external expansion value to obtain an expanded measuring area range.

5. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 1, wherein an equal proportion method is adopted for carrying out retraction processing to obtain an effective coverage area of each airborne laser point cloud aerial zone, and the method specifically comprises the following steps:

calculating the position of each laser point pair in the navigation band boundary point pair set subjected to retraction processing by an equal proportion method according to the navigation band boundary point pair set and the minimum point cloud navigation band overlapping proportion standard value;

according to the obtained time attribute values, carrying out ascending arrangement on concentrated left boundary points of the flight band boundary points subjected to the retraction processing by the equal proportion method to obtain a first sequence;

according to the obtained time attribute values, carrying out descending arrangement on the concentrated right boundary points of the flight band boundary points subjected to the retraction processing by the equal proportion method to obtain a second sequence;

and sequentially connecting the first sequence and the second sequence to generate an effective coverage area of the airborne laser point cloud navigation band.

6. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 1, wherein an integral method is adopted for carrying out retraction processing to obtain an effective coverage area of each airborne laser point cloud aerial zone, and the method specifically comprises the following steps:

arranging the left boundary points in the boundary point set of the airborne laser point cloud flight band in an ascending order according to the acquired time attribute values to obtain a third sequence;

arranging the right boundary points in the boundary point set of the airborne laser point cloud flight band in a descending order according to the acquired time attribute values to obtain a fourth sequence;

sequentially connecting the third sequence and the fourth sequence to generate a polygonal area;

calculating the buffer value of each strip laser point cloud navigation band according to the width of the airborne laser point cloud navigation band and the minimum point cloud navigation band overlapping ratio standard value;

and carrying out retraction processing on the polygonal area based on the buffer value to obtain an effective coverage area of the airborne laser point cloud navigation band.

7. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 1, wherein the extracting the boundary point set of the airborne laser point cloud aerial zone based on the airborne laser point cloud data set specifically comprises:

determining a set formed by laser points of which the heading edge attribute value is yes and the absolute value of the scanning angle attribute value is greater than a set angle threshold value as a boundary point set of the airborne laser point cloud navigation band; the laser point with the negative attribute value of the boundary point centralized scanning angle of the airborne laser point cloud navigation band is the left boundary point, and the laser point with the positive attribute value of the boundary point centralized scanning angle of the airborne laser point cloud navigation band is the right boundary point.

8. The method for detecting the airborne laser point cloud aerial photography vulnerability according to claim 1, wherein the step of screening the air belt boundary point pair set according to the time information and the air belt boundary point set of the airborne laser point cloud aerial belt and calculating the width of the air belt of the airborne laser point cloud aerial belt specifically comprises the steps of:

determining a set formed by boundary points of which the interval value of the acquisition time attribute values of the boundary points on the left side and the boundary points on the right side in the boundary point set of the airborne laser point cloud flight band is minimum and the interval value is smaller than a set time threshold as a flight band boundary point set;

calculating the plane Euclidean distance of each boundary point pair in the navigation band boundary point pair set to obtain a navigation band width set;

and determining the maximum width, the minimum width and the average width in the navigation band width set to obtain the width of the airborne laser point cloud navigation band.

9. The utility model provides an airborne laser point cloud aerial photograph leak detection system which characterized in that includes:

the data acquisition module is used for acquiring the airborne laser point cloud data set and corresponding time information;

the boundary point extraction module is used for extracting a boundary point set of the airborne laser point cloud navigation band based on the airborne laser point cloud data set;

the first calculation module is used for screening a zone boundary point pair set according to the time information and the boundary point set of the airborne laser point cloud flight band and calculating the width of the airborne laser point cloud flight band;

the second calculation module is used for carrying out retraction processing by adopting an equal proportion method or an integral method based on the boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and the flight band boundary point pair set to obtain an effective coverage area of each airborne laser point cloud flight band;

the relative vulnerability determining module is used for superposing and comparing the effective coverage area of the flight band with a survey area range and determining whether relative vulnerabilities exist in the survey area range or not;

and the absolute vulnerability determination module is used for determining whether absolute vulnerabilities exist in the measuring area range by adopting a grid method based on the airborne laser point cloud data set.

10. The airborne laser point cloud aerial photography vulnerability detection system according to claim 9, wherein the relative vulnerability determination module specifically comprises:

the merging unit is used for merging the effective coverage areas of all airborne laser point cloud navigation belts to obtain a union set of the effective coverage areas;

the external expansion unit is used for externally expanding the range of the measuring area to obtain the expanded range of the measuring area;

the superposition comparison unit is used for superposing and comparing the expanded measurement area range and the effective coverage area union set, and judging whether an area which is not covered by the effective coverage area exists in the expanded measurement area range to obtain a first judgment result;

a relative vulnerability determining unit, configured to determine that a relative vulnerability exists if the first determination result is yes, and determine, as a relative vulnerability region, a region within the extended measurement region that is not covered by the effective coverage region; and if the first judgment result is negative, no relative bug exists.

Technical Field

The invention relates to the field of image processing, in particular to an airborne laser point cloud aerial photography vulnerability detection method and system.

Background

In recent years, the laser radar technology is rapidly developed, the equipment has lighter weight, smaller volume and higher precision, and the laser radar equipment is widely applied to the production of digital surface models, digital elevation models, digital orthographic images and three-dimensional models. However, due to the limitation of the active imaging mode of the airborne laser radar, the field angle is small, the flight height is low, the influence of factors such as topographic relief, wind power and ground object mirror reflection during aerial photography is large, an aerial photography hole area is easy to appear, and the use of data is directly influenced. The currently adopted human-computer interactive laser point cloud aerial photography vulnerability detection method has low efficiency and poor reliability and scientificity, and can not meet the requirement of airborne laser point cloud data quality control.

Disclosure of Invention

Therefore, it is necessary to provide a method and a system for detecting airborne laser point cloud aerial photography vulnerabilities, so as to improve the vulnerability detection efficiency and reliability.

In order to achieve the purpose, the invention provides the following scheme:

an airborne laser point cloud aerial photography vulnerability detection method comprises the following steps:

acquiring an airborne laser point cloud data set and corresponding time information;

extracting a boundary point set of an airborne laser point cloud navigation band based on the airborne laser point cloud data set;

screening a zone boundary point pair set according to the time information and the boundary point set of the airborne laser point cloud flight band, and calculating the width of the airborne laser point cloud flight band;

performing retraction processing by adopting an equal proportion method or an integral method based on the boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and the flight band boundary point pair set to obtain an effective coverage area of each airborne laser point cloud flight band;

overlapping and comparing the effective coverage area of the flight band with a survey area range, and determining whether a relative bug exists in the survey area range;

and determining whether absolute holes exist in the measuring area range or not by adopting a grid method based on the airborne laser point cloud data set.

Optionally, the overlapping the effective coverage area of the flight band and the survey area range to determine whether the survey area range has a relative bug specifically includes:

combining the effective coverage areas of all airborne laser point cloud flight strips to obtain a union set of the effective coverage areas;

expanding the measuring area range to obtain an expanded measuring area range;

superposing and comparing the expanded measuring area range and the effective coverage area union set, and judging whether an area which is not covered by the effective coverage area exists in the expanded measuring area range to obtain a first judgment result;

if the first judgment result is yes, a relative bug exists, and the area which is not covered by the effective coverage area in the expanded measurement area range is determined as a relative bug area;

and if the first judgment result is negative, no relative bug exists.

Optionally, based on the airborne laser point cloud data set, determining whether an absolute leak exists in the survey area range by using a grid method specifically includes:

splicing and fusing the airborne laser point cloud data set to obtain survey area laser point cloud data;

generating an empty raster data set with zero raster values according to set grid intervals on the basis of the laser point cloud data of the survey area;

counting the number of laser points in each grid, and assigning a value to the empty grid data set according to the number of the laser points to obtain a point cloud density map of the survey area;

expanding the measuring area range to obtain an expanded measuring area range;

and setting zero-value pixels in the point cloud density map of the measured area as invalid values, and performing visual superposition comparison on the point cloud density map of the measured area and the expanded measured area range to determine whether an absolute leak exists in the measured area range.

Optionally, the step of performing external expansion on the measurement area range to obtain the extended measurement area range specifically includes:

using a formulaCalculating an external expansion value of the measuring area range; wherein e is the extension value of the measuring region range, T_AThe distance beyond the measuring area is required for the effective coverage area of the laser point cloud, B^jThe buffer value of the jth strip laser-carried point cloud navigation band is obtained by adopting an equal proportion method or an integral method for retraction processing;

and expanding the measuring area range by the external expansion value to obtain an expanded measuring area range.

Optionally, performing retraction processing by using an equal proportion method to obtain an effective coverage area of each airborne laser point cloud flight strip, specifically comprising:

calculating the position of each laser point pair in the navigation band boundary point pair set subjected to retraction processing by an equal proportion method according to the navigation band boundary point pair set and the minimum point cloud navigation band overlapping proportion standard value;

according to the obtained time attribute values, carrying out ascending arrangement on concentrated left boundary points of the flight band boundary points subjected to the retraction processing by the equal proportion method to obtain a first sequence;

according to the obtained time attribute values, carrying out descending arrangement on the concentrated right boundary points of the flight band boundary points subjected to the retraction processing by the equal proportion method to obtain a second sequence;

and sequentially connecting the first sequence and the second sequence to generate an effective coverage area of the airborne laser point cloud navigation band.

Optionally, an integral method is adopted for retraction processing, so as to obtain an effective coverage area of each airborne laser point cloud flight band, and the method specifically comprises the following steps:

arranging the left boundary points in the boundary point set of the airborne laser point cloud flight band in an ascending order according to the acquired time attribute values to obtain a third sequence;

arranging the right boundary points in the boundary point set of the airborne laser point cloud flight band in a descending order according to the acquired time attribute values to obtain a fourth sequence;

sequentially connecting the third sequence and the fourth sequence to generate a polygonal area;

calculating the buffer value of each strip laser point cloud navigation band according to the width of the airborne laser point cloud navigation band and the minimum point cloud navigation band overlapping ratio standard value;

and carrying out retraction processing on the polygonal area based on the buffer value to obtain an effective coverage area of the airborne laser point cloud navigation band.

Optionally, the extracting a boundary point set of the airborne laser point cloud flight band based on the airborne laser point cloud data set specifically includes:

determining a set formed by laser points of which the heading edge attribute value is yes and the absolute value of the scanning angle attribute value is greater than a set angle threshold value as a boundary point set of the airborne laser point cloud navigation band; the laser point with the negative attribute value of the boundary point centralized scanning angle of the airborne laser point cloud navigation band is the left boundary point, and the laser point with the positive attribute value of the boundary point centralized scanning angle of the airborne laser point cloud navigation band is the right boundary point.

Optionally, the screening of the fairway zone boundary point pair set according to the time information and the boundary point set of the airborne laser point cloud fairway zone, and the calculation of the width of the airborne laser point cloud fairway zone specifically include:

determining a set formed by boundary points of which the interval value of the acquisition time attribute values of the boundary points on the left side and the boundary points on the right side in the boundary point set of the airborne laser point cloud flight band is minimum and the interval value is smaller than a set time threshold as a flight band boundary point set;

calculating the plane Euclidean distance of each boundary point pair in the navigation band boundary point pair set to obtain a navigation band width set;

and determining the maximum width, the minimum width and the average width in the navigation band width set to obtain the width of the airborne laser point cloud navigation band.

The invention also provides an airborne laser point cloud aerial photography vulnerability detection system, which comprises:

the data acquisition module is used for acquiring the airborne laser point cloud data set and corresponding time information;

the boundary point extraction module is used for extracting a boundary point set of the airborne laser point cloud navigation band based on the airborne laser point cloud data set;

the first calculation module is used for screening a zone boundary point pair set according to the time information and the boundary point set of the airborne laser point cloud flight band and calculating the width of the airborne laser point cloud flight band;

the second calculation module is used for carrying out retraction processing by adopting an equal proportion method or an integral method based on the boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and the flight band boundary point pair set to obtain an effective coverage area of each airborne laser point cloud flight band;

the relative vulnerability determining module is used for superposing and comparing the effective coverage area of the flight band with a survey area range and determining whether relative vulnerabilities exist in the survey area range or not;

and the absolute vulnerability determination module is used for determining whether absolute vulnerabilities exist in the measuring area range by adopting a grid method based on the airborne laser point cloud data set.

Optionally, the relative vulnerability determining module specifically includes:

the merging unit is used for merging the effective coverage areas of all airborne laser point cloud navigation belts to obtain a union set of the effective coverage areas;

the external expansion unit is used for externally expanding the range of the measuring area to obtain the expanded range of the measuring area;

the superposition comparison unit is used for superposing and comparing the expanded measurement area range and the effective coverage area union set, and judging whether an area which is not covered by the effective coverage area exists in the expanded measurement area range to obtain a first judgment result;

a relative vulnerability determining unit, configured to determine that a relative vulnerability exists if the first determination result is yes, and determine, as a relative vulnerability region, a region within the extended measurement region that is not covered by the effective coverage region; and if the first judgment result is negative, no relative bug exists.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides an airborne laser point cloud aerial photography vulnerability detection method and system, wherein a boundary point set of an airborne laser point cloud aerial zone is extracted based on an airborne laser point cloud data set; calculating the width of the airborne laser point cloud navigation band; performing retraction processing by adopting an equal proportion method or an integral method based on a boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and a flight band boundary point pair set to obtain an effective coverage area of each airborne laser point cloud flight band; overlapping and comparing the effective coverage area of the flight band with the measuring area range to determine whether a relative bug exists in the measuring area range; and determining whether absolute leaks exist in the measuring area range by adopting a grid method based on the airborne laser point cloud data set. The method can automatically extract the irregular vector boundary of the flight band and the effective coverage area of the flight band, realizes automation, integration, high efficiency and visualization of laser point cloud vulnerability detection, improves the efficiency and reliability of vulnerability detection, and can meet the requirement of airborne laser point cloud data quality control.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a flowchart of an airborne laser point cloud aerial photography vulnerability detection method provided by an embodiment of the present invention;

FIG. 2 is a diagram of the effective coverage area of the laser point cloud navigation band of the present invention;

FIG. 3 is a laser point cloud navigation band boundary diagram of the present invention;

FIG. 4 is a relative hole map of the laser point cloud of the present invention;

FIG. 5 is an absolute loophole map of the laser point cloud of the present invention;

fig. 6 is a structural diagram of an airborne laser point cloud aerial photograph vulnerability detection system provided in an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Fig. 1 is a flowchart of an airborne laser point cloud aerial photography vulnerability detection method according to an embodiment of the present invention.

Referring to fig. 1, the method for detecting the airborne laser point cloud aerial photography vulnerability includes:

step 101: and acquiring an airborne laser point cloud data set and corresponding time information.

Step 102: and extracting a boundary point set of the airborne laser point cloud navigation band based on the airborne laser point cloud data set.

Step 103: and screening a zone boundary point pair set according to the time information and the boundary point set of the airborne laser point cloud flight band, and calculating the width of the airborne laser point cloud flight band.

Step 104: and performing retraction processing by adopting an equal proportion method or an integral method based on the boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band and the flight band boundary point pair set to obtain the effective coverage area of each airborne laser point cloud flight band.

Step 105: and overlapping and comparing the effective coverage area of the flight band with the survey area range, and determining whether a relative bug exists in the survey area range.

The method specifically comprises the following steps:

1) and combining the effective coverage areas of all airborne laser point cloud flight belts to obtain a union set of the effective coverage areas.

2) And carrying out external expansion on the measuring region range to obtain the expanded measuring region range.

3) And superposing and comparing the expanded measuring area range and the effective coverage area union set, and judging whether an area which is not covered by the effective coverage area exists in the expanded measuring area range to obtain a first judgment result. If the first judgment result is yes, a relative bug exists, and the area which is not covered by the effective coverage area in the expanded measurement area range is determined as a relative bug area; and if the first judgment result is negative, no relative bug exists.

Step 106: and determining whether absolute holes exist in the measuring area range or not by adopting a grid method based on the airborne laser point cloud data set.

The method specifically comprises the following steps:

1) and splicing and fusing the airborne laser point cloud data set to obtain survey area laser point cloud data.

2) And generating an empty raster data set with zero raster values according to the set grid spacing based on the laser point cloud data of the survey area.

3) And counting the number of laser points in each grid, and assigning a value to the empty grid data set according to the number of the laser points to obtain a point cloud density map of the survey area.

4) And carrying out external expansion on the measuring region range to obtain the expanded measuring region range.

5) And setting zero-value pixels in the point cloud density map of the measured area as invalid values, and performing visual superposition comparison on the point cloud density map of the measured area and the expanded measured area range to determine whether an absolute leak exists in the measured area range.

Wherein, step 104 adopts the integral method to carry out retraction processing, obtains the effective coverage area of each airborne laser point cloud flight strip, specifically includes:

arranging the left boundary points in the boundary point set of the airborne laser point cloud flight band in an ascending order according to the acquired time attribute values to obtain a third sequence; arranging the right boundary points in the boundary point set of the airborne laser point cloud flight band in a descending order according to the acquired time attribute values to obtain a fourth sequence; sequentially connecting the third sequence and the fourth sequence to generate a polygonal area; calculating the buffer value of each strip laser point cloud navigation band according to the width of the airborne laser point cloud navigation band and the minimum point cloud navigation band overlapping ratio standard value; and carrying out retraction processing on the polygonal area based on the buffer value to obtain an effective coverage area of the airborne laser point cloud navigation band.

Wherein, in step 104, an equal proportion method is adopted for carrying out retraction processing to obtain the effective coverage area of each airborne laser point cloud navigation band, and the method specifically comprises the following steps:

calculating the position of each laser point pair in the navigation band boundary point pair set subjected to retraction processing by an equal proportion method according to the navigation band boundary point pair set and the minimum point cloud navigation band overlapping proportion standard value; according to the obtained time attribute values, carrying out ascending arrangement on concentrated left boundary points of the flight band boundary points subjected to the retraction processing by the equal proportion method to obtain a first sequence; according to the obtained time attribute values, carrying out descending arrangement on the concentrated right boundary points of the flight band boundary points subjected to the retraction processing by the equal proportion method to obtain a second sequence; and sequentially connecting the first sequence and the second sequence to generate an effective coverage area of the airborne laser point cloud navigation band.

In step 102, extracting a boundary point set of an airborne laser point cloud flight strip based on the airborne laser point cloud data set specifically includes:

determining a set formed by laser points of which the heading edge attribute value is yes and the absolute value of the scanning angle attribute value is greater than a set angle threshold value as a boundary point set of the airborne laser point cloud navigation band; the laser point with the negative attribute value of the boundary point centralized scanning angle of the airborne laser point cloud navigation band is the left boundary point, and the laser point with the positive attribute value of the boundary point centralized scanning angle of the airborne laser point cloud navigation band is the right boundary point.

In step 102, screening a sideband boundary point pair set according to the time information and the airborne laser point cloud sideband boundary point set, and calculating the width of the airborne laser point cloud sideband, specifically comprising:

determining a set formed by boundary points of which the interval value of the acquisition time attribute values of the boundary points on the left side and the boundary points on the right side in the boundary point set of the airborne laser point cloud flight band is minimum and the interval value is smaller than a set time threshold as a flight band boundary point set; calculating the plane Euclidean distance of each boundary point pair in the navigation band boundary point pair set to obtain a navigation band width set; and determining the maximum width, the minimum width and the average width in the navigation band width set to obtain the width of the airborne laser point cloud navigation band.

In step 105 and step 106, the step of extending the measurement area range to obtain an extended measurement area range specifically includes:

using a formulaCalculating an external expansion value of the measuring area range; wherein e is the extension value of the measuring region range, T_AThe distance beyond the measuring area is required for the effective coverage area of the laser point cloud, B^jThe buffer value of the jth strip laser-carried point cloud navigation band is obtained by adopting an equal proportion method or an integral method for retraction processing; and expanding the measuring area range by the external expansion value to obtain an expanded measuring area range.

In practical application, the specific implementation process of the airborne laser point cloud aerial photography vulnerability detection method in the implementation is as follows:

step 1: and traversing the laser point cloud data set, and extracting a boundary point set of the airborne laser point cloud navigation band based on the attribute values of the 'route edge' and the 'scanning angle' of the airborne laser point.

Firstly, traversing an airborne laser point cloud data set, and when the attribute value of the 'route edge' of an airborne laser point is 'yes' and the absolute value of the attribute value of the 'scanning angle' is larger than a set angle threshold A_minThen, the point is extracted and put into a 'boundary point set' P ═ P of the navigation band_i}_i＝1,NIn the middle, if the extracted boundary points are more and dense, the "boundary point set" P can be thinned based on the acquisition time of the laser point, and generally a_minMay be set to 5.

Then, classifying the boundary point set P into a left boundary point set P according to the positive and negative of the scanning angle attribute value of the point cloud_LAnd "Right set of boundary points" P_RIn general, a laser spot with a negative "scan angle" attribute value can be classified as a "left side boundary point set" P_L"scan angle" belongs toLaser points with positive sex value are classified into a right side boundary point set P_R。

Step 2: and calculating the width of the airborne laser point cloud navigation band by using the acquired time information of the laser points.

Sequentially from the point cloud navigation band ' left and right boundary point set ' P ' in the step 1_LAnd P_RIn the method, the attribute value of the extraction 'acquisition time' has the minimum interval and the interval value is less than the set time threshold value T_tThe boundary point pair of (2) calculates the plane Euclidean distance of the boundary point pair, namely the width of the position of the flight band

And puts the point pair into the point pair set M. Subsequently, a navigation band width set W is statistically extracted^jMaximum width ofMinimum width

Average widthThe set time threshold value T_tThe method is mainly used for ensuring that the connecting line of the extracted boundary point pair is perpendicular to the flight direction so as to represent the width of the position of the flight band, and generally a time threshold T is set_tMay be set to 0.1 second.

And step 3: and (4) utilizing an equal proportion method or an integral method to carry out retraction processing on the boundary points of the airborne laser point cloud flight band, and calculating the effective coverage area of the airborne laser point cloud flight band.

1) The method for calculating the effective coverage area of the airborne laser point cloud flight band by using the equal-proportion internal contraction method comprises the following steps:

firstly, obtaining a standard value k of the minimum point cloud flight band overlapping proportion according to standard specifications and technical design books, wherein k is generally 13%.

Then, the laser point pair P (x ') after retraction was calculated by the following formula'_iL,y'_iL) And P (x'_iR,y'_iR) In the position of (a) in the first,

wherein, P (x)_iL,y_iL) And P (x)_iR,y_iR) The point pairs in the boundary point pair set M in step 2 are shown in fig. 2.

And then, arranging the left boundary points after the inward contraction according to an ascending order and arranging the right boundary points according to a descending order respectively by using the attribute value of 'acquisition time' of the laser points.

Finally, the sorted left and right side inward shrinkage boundary points are connected in sequence to generate a polygon tightly wrapping the whole navigation band

The point cloud navigation band boundary is the jth laser point cloud navigation band boundary after retraction.

2) The method for effectively covering the area by the airborne laser point cloud flight band by the integral method comprises the following steps:

firstly, the attribute value of 'acquisition time' of the laser spot is used for dividing the 'left side boundary point set' P in the step 1_LArranged in ascending order, a set of "right side boundary points" P_RThe boundary points in (1) are arranged in descending order.

Then, the sorted left and right boundary points are connected in sequence to generate a polygon tightly wrapping the whole navigation band

WR^jI.e. the boundary of the jth laser point cloud flight band, as shown in fig. 3.

Finally, using the formulaCalculating the buffer value WB of the jth laser point cloud flight band^jAnd based on the buffer value WB^jWR (Point-cloud) boundary of aerial zone^jIs retracted into

I.e. the effective coverage area of the flight band based on the standard value k of the degree of overlap,

is the value calculated in step 2. Calculate buffer value WB^jIn time, the maximum width of the flight band calculated in the step 2 can be adopted according to the requirement

Or minimum width

And 4, step 4: and (5) overlapping and comparing the effective coverage area and the measuring area range of the flight band, and detecting whether the airborne laser point cloud has relative loopholes.

Firstly, calculating the effective coverage area of all flight zones in the measuring area in the step 3

OrR.

Then, using the formulaCalculating an external expansion value e of the measuring area, and expanding the range of the measuring area based on the external expansion value e, wherein T_AIndicating the distance, T, by which the laser point cloud effective area should exceed the survey area_AThe value is typically 500 meters. When the union R is all

When forming a set, B^jThe buffer value of the jth strip laser-carried point cloud aerial belt obtained by adopting the integral retraction processing, namely WB^j(ii) a When the union R is all

When forming a set, B^jThe buffer value of the jth strip laser point cloud aerial belt obtained by adopting an equal proportion method or an integral method for retraction processing, the buffer value and WB (wideband) under the method^jThe calculation formula of (2) is the same.

Finally, extracting the area which is not covered by the effective coverage area R of the flight zone in the extended measurement area range, wherein the area is the relative vulnerability of the measurement area, as shown in fig. 4.

And 5: and detecting whether the airborne laser point cloud has an absolute leak or not based on the rasterized point cloud density map.

Firstly, based on spatial position splicing, fusing and processing all navigation band data in a survey area to generate survey area laser point cloud data L, wherein the navigation band data is original laser point cloud data and is consistent with the laser point cloud data set in the step 1.

And then, generating a null grid data set I with zero grid values according to a set grid spacing g by using the range of the laser point cloud L of the survey area, wherein the value of the grid spacing g is determined according to the requirement on the point cloud density in the design book.

And then counting the number of laser points falling in each grid, assigning values to corresponding grids, and obtaining a point cloud density map D of the survey area.

Finally, setting the zero-value pixel of the point cloud density grid map D as an invalid value and based on the range-extending distance value T_AAnd expanding the survey area, visually superposing and comparing the point cloud density grid map and the expanded survey area range, and extracting an absolute loophole area, as shown in fig. 5.

The invention also provides an airborne laser point cloud aerial photograph leak detection system, and fig. 6 is a structural diagram of the airborne laser point cloud aerial photograph leak detection system provided by the embodiment of the invention.

Referring to fig. 6, the airborne laser point cloud aerial photography vulnerability detection system of the present embodiment includes:

and the data acquisition module 601 is used for acquiring the airborne laser point cloud data set and the corresponding time information.

A boundary point extracting module 602, configured to extract a boundary point set of the airborne laser point cloud flight band based on the airborne laser point cloud data set.

The first calculation module 603 is configured to screen a sideband boundary point pair set according to the time information and the airborne laser point cloud sideband boundary point set, and calculate a width of the airborne laser point cloud sideband.

And a second calculating module 604, configured to perform retraction processing by using an equal proportion method or an integral method based on the boundary point set of the airborne laser point cloud flight band, the width of the airborne laser point cloud flight band, and the flight band boundary point pair set, so as to obtain an effective coverage area of each airborne laser point cloud flight band.

And a relative vulnerability determining module 605, configured to perform superposition comparison on the effective coverage area of the flight zone and a survey area range, and determine whether a relative vulnerability exists in the survey area range.

And an absolute vulnerability determining module 606, configured to determine whether an absolute vulnerability exists in the survey area range by using a grid method based on the airborne laser point cloud data set.

As an optional implementation manner, the relative vulnerability determining module 605 specifically includes:

and the merging unit is used for merging the effective coverage areas of all the airborne laser point cloud navigation bands to obtain a union set of the effective coverage areas.

And the external expansion unit is used for externally expanding the range of the measurement area to obtain the expanded range of the measurement area.

And the superposition comparison unit is used for superposing and comparing the expanded measurement area range and the effective coverage area union set, and judging whether an area which is not covered by the effective coverage area exists in the expanded measurement area range to obtain a first judgment result.

A relative vulnerability determining unit, configured to determine that a relative vulnerability exists if the first determination result is yes, and determine, as a relative vulnerability region, a region within the extended measurement region that is not covered by the effective coverage region; and if the first judgment result is negative, no relative bug exists.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.