WO2022073248A1

WO2022073248A1 - Point cloud density determination method, movable platform, and storage medium

Info

Publication number: WO2022073248A1
Application number: PCT/CN2020/120250
Authority: WO
Inventors: 杜劼熹; 黄振昊
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2020-10-10
Filing date: 2020-10-10
Publication date: 2022-04-14
Also published as: CN113544739A

Abstract

A point cloud density determination method, a movable platform, and a computer-readable storage medium. The method comprises: acquiring a target motion parameter of a movable platform in a test area, and acquiring a target scanning parameter of a laser radar carried by the movable platform (S101); and according to the target motion parameter and the target scanning parameter, calculating the point cloud density distribution, obtained by means of the movable platform working in the test area, of a point cloud of the laser radar (S102).

Description

Point cloud density determination method, movable platform and storage medium

technical field

The present application relates to the technical field of movable platforms, and in particular, to a method for determining a point cloud density, a movable platform and a storage medium.

Background technique

With the rapid development of mobile platform technologies such as unmanned aerial vehicles, the applications of mobile platforms are becoming more and more extensive. For example, mobile platforms can be used for surveying and mapping, security, and power inspection. The movable platform can be equipped with sensors such as cameras, ultrasonic rangefinders, millimeter-wave radars, lidars, etc. to obtain data information of the survey area, such as image information, distance information, etc. Among them, through the radar sensor, the point cloud data of the survey area can be obtained. However, the point cloud data is a kind of sparse sampling data, whether the sampling data can better reflect the measurement results of the survey area lacks an intuitive reflection.

SUMMARY OF THE INVENTION

Based on this, the embodiments of the present application provide a point cloud density determination method, a movable platform, and a storage medium, which aim to determine the point cloud density distribution about the survey area, so as to provide users with intuitive operation indicators.

In a first aspect, the present application provides a method for determining a point cloud density, including:

acquiring the target motion parameters of the movable platform in the survey area, and acquiring the target scanning parameters of the lidar mounted on the movable platform;

According to the target motion parameter and the target scanning parameter, the point cloud density distribution of the point cloud of the lidar obtained by the movable platform in the survey area is calculated.

In a second aspect, the present application also provides a movable platform, the movable platform includes a memory and a processor;

the memory is used to store computer programs;

The processor is configured to execute the computer program, and when executing the computer program, implement the above-mentioned method for determining the density of a point cloud.

In a third aspect, the present application also provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the processor enables the processor to achieve the above point cloud density Determine the method.

The point cloud density determination method, movable platform and storage medium disclosed in the present application determine the point cloud density distribution about the survey area, so as to provide users with intuitive operation indicators.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not limiting of the present application.

Description of drawings

In order to explain the technical solutions of the embodiments of the present application more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. For those of ordinary skill, other drawings can also be obtained from these drawings without any creative effort.

1 is a schematic block diagram of a movable platform system provided by an embodiment of the present application;

2 is a schematic flowchart of steps of a method for determining a point cloud density provided by an embodiment of the present application;

FIG. 3 is a schematic diagram of the scanning range of the lidar loaded on the movable platform;

4 is a schematic diagram of a point cloud density feature distribution provided by an embodiment of the present application;

5 is a schematic diagram of a discretization of the number of point clouds provided by an embodiment of the present application;

6 is a schematic diagram of a reference point cloud density distribution provided by an embodiment of the present application;

7 is a schematic diagram of point cloud density distribution corresponding to a route 1 and route 2 respectively provided by an embodiment of the present application;

8 is a schematic diagram of overall point cloud density distribution corresponding to a route 1 and route 2 provided by an embodiment of the present application;

FIG. 9 is a corresponding overall reference point cloud density curve diagram when the overlap rate is R0 provided by an embodiment of the present application;

10 is a graph of the overall reference point cloud density corresponding to an overlap ratio R1 provided by an embodiment of the present application;

Fig. 11 is a kind of lowest point cloud density curve graph provided by the embodiment of the present application;

12 is a schematic flowchart of steps for calculating the point cloud density distribution of the lidar point cloud obtained by the movable platform operating in the survey area provided by an embodiment of the present application;

13 is a graph showing the corresponding lowest point cloud density under various motion parameters and scanning parameters provided by an embodiment of the present application;

FIG. 14 is a schematic block diagram of a movable platform provided by an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

The flowcharts shown in the figures are for illustration only, and do not necessarily include all contents and operations/steps, nor do they have to be performed in the order described. For example, some operations/steps can also be decomposed, combined or partially combined, so the actual execution order may be changed according to the actual situation.

It should be understood that the terms used in the specification of the present application herein are for the purpose of describing particular embodiments only and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise.

It will also be understood that, as used in this specification and the appended claims, the term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and features in the embodiments may be combined with each other without conflict.

The embodiments of the present application provide a point cloud density determination method, a movable platform and a storage medium, which are used to improve the accuracy and reliability of acquiring the point cloud density distribution of the survey area.

Please refer to FIG. 1. FIG. 1 is a schematic block diagram of a movable platform system according to an embodiment of the present application. As shown in FIG. 1 , the movable platform system 1000 may include the movable platform 100 and the lidar 200 mounted on the movable platform 100 , wherein the movable platform 100 includes a power system 110 and a controller 120 of the movable platform. The power system 110 is used to provide power for the movable platform 100, and the controller 120 of the movable platform is used to control the movable platform 100 to operate in the survey area. The survey area can be scanned by the lidar 200 to obtain information such as the point cloud density distribution of the survey area.

Illustratively, the movable platform 100 includes, but is not limited to, unmanned aerial vehicles, such as rotorcraft, including mono-rotors, dual-rotors, tri-rotors, quad-rotors, hexa-rotors, octa-rotors, ten-rotors, Twelve-rotor aircraft, etc. Of course, the movable platform 100 may also be other types of unmanned aerial vehicles or movable devices, such as fixed-wing unmanned aerial vehicles, and the embodiment of the present application is not limited thereto.

Exemplarily, the power system 110 may include one or more electronic governors (referred to as ESCs for short), one or more propellers, and one or more motors corresponding to the one or more propellers, wherein the motors are connected to the electronic between the governor and the propeller. The electronic governor is used to provide driving current to the motor to control the speed of the motor. The motor is used to drive the propeller to rotate, thereby providing power for the flight of the movable platform 100, and the power enables the movable platform 100 to achieve one or more degrees of freedom movement. In certain embodiments, the movable platform 100 may rotate about one or more axes of rotation. It should be understood that the motor may be a DC motor or an AC motor. In addition, the motor may be a brushless motor or a brushed motor.

It can be understood that the above naming of the components of the movable platform is only for the purpose of identification, and therefore does not limit the embodiments of the present application.

Hereinafter, the method for determining the point cloud density provided by the embodiments of the present application will be described in detail with reference to the movable platform in FIG. 1 . It should be noted that the movable platform in FIG. 1 is only used to explain the method for determining the point cloud density provided by the embodiment of the present application, but does not constitute a limitation on the application scenario of the method for determining the point cloud density provided by the embodiment of the present application.

Please refer to FIG. 2 , which is a schematic flowchart of a method for determining a point cloud density provided by an embodiment of the present application. The method for determining the point cloud density can be used in the above-mentioned movable platform system, that is, executed by the movable platform 100 in FIG. It is implemented by other control devices carried on 100, and the embodiment of the present application is not limited to this.

In order to facilitate the detailed description of the embodiments of the present application, the following description is given by taking the point cloud density determination method applied to a movable platform as an example, so as to improve the accuracy and reliability of the point cloud density distribution obtained in the survey area.

As shown in FIG. 2 , the method for determining the point cloud density specifically includes steps S101 to S102.

S101. Acquire target motion parameters of the movable platform in the survey area, and acquire target scanning parameters of the lidar mounted on the movable platform.

The target motion parameters of the movable platform in the survey area include but are not limited to the distance between the movable platform and the survey area, the moving speed of the movable platform, and the overlapping rate of the moving routes of the movable platform. The overlap rate of the mobile platform's moving route, that is, the side overlap rate, refers to the proportion of the overlapping portion of the mobile platform's operation on the first route and the operation on the second route.

The distance between the movable platform and the measurement area can be represented to a certain extent as the distance between the lidar mounted on the movable platform and the measurement area. If the movable platform is an aircraft, the distance may be expressed as the height of the movable platform from the ground survey area.

The moving speed of the movable platform can be directly input by the user, or can be determined according to the movement performance of the movable platform, such as the rated speed limit of the movable platform and the like. In addition, it can also be determined according to other tasks performed by the movable platform. For example, if the movable platform performs the photographing task at the same time, and there is a fixed shooting time interval and shooting overlap range between the photos, the corresponding movable platform The speed of movement can also be determined.

The overlap rate of the movable platform travel routes can be identified as the separation distance between adjacent route segments. Taking the common "bow"-shaped route (serpentine route) as an example, that is, the farther the distance between the route and the route, the smaller the overlap rate; the smaller the distance between the route and the route, the greater the overlap rate.

The target scanning parameters of the lidar mounted on the movable platform include but are not limited to the laser emission frequency, scanning mode and scanning frame rate of the lidar. Among them, the scanning mode of the lidar corresponds to the pattern of the scanned point cloud, such as an oscillation (or pendulum) scanning mode, a rotating scanning mode, and the like. The scanning frame rate refers to the period of the point cloud image generated by the lidar, that is, how long it takes to generate a point cloud image.

In some embodiments, acquiring the target motion parameters of the movable platform in the survey area, and acquiring the target scanning parameters of the lidar mounted on the movable platform may include: receiving the target motion input by the user on the user interface of the movable platform parameters and target scan parameters.

In some embodiments, acquiring the target motion parameters of the movable platform in the survey area includes: calculating and obtaining the target motion parameters based on set task information. That is to say, the target motion parameter may be calculated by the executing subject based on the content related to the task. For example, it is possible to obtain the scene type of the survey area, whether it is a desert or a wetland, a plain or a mountain, and further calculate and determine the motion parameters based on the task information.

In order to facilitate user operation and improve user experience, the corresponding target motion parameters and target scanning parameter setting functions are configured on the user interface of the movable platform. The user can input the corresponding target motion parameters and targets on the user interface of the movable platform Scan parameters, such as inputting the distance between the movable platform and the survey area, the moving speed of the movable platform, the overlapping rate of the moving route of the movable platform, as well as various parameters such as laser emission frequency, scanning mode, and scanning frame rate. The target motion parameters and target scanning parameters input by the user on the user interface of the movable platform are received, so as to obtain the target motion parameters of the movable platform in the survey area and the target scanning parameters of the lidar.

S102 , according to the target motion parameter and the target scanning parameter, calculate the point cloud density distribution of the point cloud of the lidar obtained by the movable platform operating in the survey area.

In the actual operation process, what the user is most concerned about is usually not how much the average point cloud density can achieve, but how much the lowest point cloud density in the survey area can achieve. The point cloud density distribution of the point cloud is determined, and the lowest point cloud density of the lidar point cloud obtained by the movable platform in the survey area is determined.

In order to obtain the point cloud density distribution, for example, obtain the target motion parameters of the movable platform in the survey area, such as the distance between the movable platform and the survey area, the moving speed of the movable platform, the overlap rate of the moving route of the movable platform, etc., And the target scanning parameters of the laser radar such as laser emission frequency, scanning mode, scanning frame rate, etc. In addition to acquiring the target motion parameters and target scanning parameters, the preset point cloud distribution information of the lidar is also acquired, wherein the preset point cloud distribution information is measured under the preset motion parameters of the movable platform and the preset scanning parameters of the lidar owned. That is, preset motion parameters such as the reference height of the corresponding movable platform, the reference moving speed of the movable platform, the reference overlap rate of the moving route of the movable platform, etc., as well as the reference transmission frequency, reference scanning mode, reference scanning frame rate. Waiting for the preset scanning parameters of the lidar, the movable platform operates based on the preset motion parameters of the movable platform and the preset scanning parameters of the lidar, and the preset point cloud distribution information is obtained by measurement. And, the preset point cloud distribution information is saved.

In some embodiments, acquiring preset point cloud distribution information of the lidar may include: acquiring the scanning range of the lidar and multiple overlapping rates of multiple routes of the movable platform; The multiple overlapping ratios are used to determine the point cloud density of the overlapping area and the point cloud density of the non-overlapping area; the preset point cloud distribution information is generated based on the point cloud density of the overlapping area and the point cloud density of the non-overlapping area.

For example, assuming that the reference height of the movable platform is H ₀ and the FOV (Field of View, field of view) of the lidar is a, as shown in FIG. 3 , determine the scanning range of the lidar L ₀ =2*H ₀ *tan(a/2).

Obtain the point cloud density characteristic distribution of the movable platform within a unit time T ₀ of 1s, or take the width of 1 meter as the particle size, and count the point cloud density corresponding to the operation of the movable platform on the basis of the reference height (such as H ₀ ). The feature distribution map, for example, as shown in Figure 4, the number of point clouds gradually decays from the center of the scan to the sides. As shown in Figure 4, at the reference height, the scanning range L of the lidar is -70 to 70 m, and the scanning range is 1 m at the center within 1 s per unit time (that is, the width W ₀ =1 m, from minus 0.5 m to plus 0.5 m) The distribution of point cloud density characteristics corresponding to the rectangular shadow part inside, the number of point clouds is about 70,000 points.

The number of point clouds in the scanning range L of the lidar is discretized and divided into rectangles with a width W ₀ of 1m, for example, as shown in Figure 5. Based on the number of discretized point clouds, the list of discretized sequences is shown in Table 1:

Table 1

As shown in Table 1, in the case of a unit time of 1s, there are L+1 segment sequences in total, the number of point clouds within 1 meter in the central part is N, and the rest are A1, A2, ..., A( L/2) and B(-1), B(-2), ..., B(-L/2). It should be noted that A(i) and B(-i) are not necessarily equal in one-to-one correspondence.

Assuming that the reference moving speed of the movable platform is V ₀ =1m/s, in FIG. 5 , the actual area of each rectangular shaded area is S ₀ =V ₀ *T ₀ *W ₀ =1m ² . The number of point clouds within 1 m ² at the center is N, then the _{_reference} point cloud density ρ at the center = N pt/m ² . For example, if the number of point clouds within 1 m ² at the center is 70,000, the _reference point cloud density ρ at the center = 70,000 pt/m ² .

For the case of uneven scanning, a more general expression is shown in Table 2:

Table 2

As shown in Table 2, under the conditions that the scanning frequency is f ₀ , the reference moving speed is V ₀ =1m/s, the width W ₀ =1m, and the unit time T ₀ is 1s, the reference point cloud of each segment in the sequence The densities are N0, N1, . . . , N(L) (in pt/m ² ), for example, as shown in Figure 6 .

Each group of adjacent routes in the multiple routes operated by the movable platform corresponds to an overlap ratio. For example, taking route 1 and route 2 of the movable platform as an example, the overlap ratio of route 1 and route 2 is R, where the overlap ratio R The value is between 0 and 1, then the overlapping area L ₀ =R*L corresponding to the route 1 and the route 2, and the non-overlapping area L1=(1-R)*L corresponding to the route 1 and the route 2.

The point cloud density feature within the range L of the lidar scanning range is discretized into an array ρ ₀ with L+1 values, then the point cloud density for the non-overlapping area of route 1 is:

in

is rounded up, and the point cloud density in the overlapping area is

in

is rounded down. For route 2, since the direction is opposite to route 1, the distribution of the array is reversed ρ ₀ , ie ρ _0-reverse . In Fig. 4 and Table 1, and for most uniformly scanned lidars, ρ ₀ is consistent with ρ _0-reverse , that is, ρ ₀ itself is symmetric. For ρ _0-reverse , when the overlap ratio is R, the point cloud density in the overlapping area is ρ _0-reverse [0:(R*L)-1], and the point cloud density in the non-overlapping area is ρ _0-reverse [(R*L):L].

Adding the two arrays, the point cloud density of the first non-overlapping area on the left is

The point cloud density in the middle overlapping area is

The point cloud density of the second non-overlapping region on the right is ρ _0-reverse [(R*L):L]. When R is 50%, the point cloud density distributions corresponding to route 1 and route 2 are shown in Figure 7, and the overall point cloud density distribution is shown in Figure 8.

And so on, assuming that when the overlap rate is R0, there are M parallel routes, then the overall reference point cloud density curve under this condition is as shown in Figure 9, ignoring the parts on both sides, then under the reference condition, the overlap rate is R0 , the lowest point cloud density in the work area is ρ ₀ '. When the overlap ratio is R1, the overall reference point cloud density curve under this condition is as shown in Figure 10, and the lowest point cloud density in the work area is ρ ₁ '. From this, it can be drawn that under the reference conditions, the overlap ratio R is the lowest point cloud density from small to large (such as from 0% (completely not covered) to 100% (completely coincident)), which can be expressed as {ρ in the form of a set _N '}, the lowest point cloud density curve is shown in Fig. 11.

Based on the obtained distance between the movable platform and the survey area, the moving speed of the movable platform, the overlapping rate of the moving route of the movable platform and other target motion parameters of the movable platform in the survey area, as well as the laser emission frequency, scanning mode, Scan the target scanning parameters of the lidar such as the frame rate, and based on the preset point cloud distribution information, calculate the point cloud density distribution of the lidar point cloud obtained by the movable platform operating in the survey area.

In some embodiments, as shown in FIG. 12 , step S102 may include sub-steps S1021 to S1023 .

S1021. Acquire a first numerical relationship between the target motion parameter and the preset motion parameter.

S1022. Acquire a second numerical relationship between the target scan parameter and the preset scan parameter.

The distance between the movable platform and the measurement area is proportional to the scanning range of the lidar, and under the condition of the same laser emission frequency, the point cloud density is inversely proportional to the scanning range, and the point cloud density is proportional to the movable platform and the measurement area. The distance and the moving speed of the movable platform are also inversely proportional. By obtaining the target motion parameters of the movable platform in the survey area and the target scanning parameters of the lidar, the first numerical relationship between the target motion parameters and the preset motion parameters, and the relationship between the target scanning parameters and the preset scanning parameters are calculated. The second numerical relationship between . Exemplarily, acquiring the first numerical relationship between the target motion parameter and the preset motion parameter may include: acquiring the distance between the movable platform and the survey area in the target motion parameter and the reference height in the preset motion parameter. first ratio.

For example, if the reference height of the movable platform in the preset motion parameters is H ₀ , and the distance between the movable platform and the survey area in the target motion parameters of the movable platform in the survey area is H, then the height H and the reference height are calculated and obtained. The first ratio between the heights H ₀ is p=H/H ₀ .

Exemplarily, obtaining the second numerical relationship between the target scanning parameter and the preset scanning parameter may include: obtaining a second ratio between the laser emission frequency of the laser radar in the target scanning parameter and the reference emission frequency in the preset scanning parameter. .

For example, if the reference emission frequency of the laser radar in the preset scanning parameters is f ₀ , and the target scanning parameters of the movable platform in the survey area, the laser emission frequency of the laser radar is f, then the laser emission frequency f and the reference emission frequency are obtained by calculating The second ratio between f ₀ is q=f/f ₀ .

S1023. According to the first numerical relationship, the second numerical relationship, and the preset point cloud distribution information, determine the point cloud of the lidar obtained by the movable platform in the survey area. Point cloud density distribution.

Based on the preset point cloud distribution information, the calculated first numerical relationship between the target motion parameters and the preset motion parameters, and the second numerical relationship between the target scanning parameters and the preset scanning parameters, the reference point cloud density is passed through The first numerical relationship and the second numerical relationship are enlarged or reduced correspondingly to obtain the point cloud density distribution of the point cloud of the lidar obtained by the movable platform operating in the survey area. Exemplarily, according to the first numerical relationship, the second numerical relationship, and the preset point cloud distribution information, determining the point cloud density distribution of the lidar point cloud obtained by the movable platform in the survey area operation may include: according to the first The ratio, the second ratio, the reference point cloud density corresponding to the preset point cloud distribution information, and the moving speed of the movable platform in the target motion parameters, determine the lowest point of the point cloud of the lidar obtained by the movable platform in the survey area operation Cloud density.

Still taking the above-mentioned examples as an example, if the first ratio between the height H of the movable platform in the survey area and the reference height H ₀ is p=H/H ₀ , the laser emission frequency f and the reference emission frequency f ₀ are between The second ratio is q=f/f ₀ , the moving speed of the movable platform in the target motion parameter of the movable platform is v m/s, the reference moving speed is V ₀ =1m/s, the preset point cloud distribution information corresponds to The lowest point cloud density in the reference point cloud density is {ρ _N '}, then the lowest point cloud density ρ of the point cloud obtained by the movable platform in the survey area to obtain the lidar is:

For example, as shown in Figure 13, the curve 1 is the lowest point cloud density distribution in the reference point cloud density; the curve 2 is the movable platform when the moving speed is 5m/s, other target motion parameters are consistent with the preset motion parameters, and the target When the scanning parameters are also consistent with the preset scanning parameters, the lowest point cloud density distribution of the point cloud of the lidar is obtained in the survey area operation; curve 3 is the movable platform when the moving speed is 1m/s, and the height is H ₀ / 4. When other target motion parameters are consistent with the preset motion parameters, and the target scanning parameters are also consistent with the preset scanning parameters, the lowest point cloud density distribution of the point cloud of the lidar is obtained in the survey area operation.

In some embodiments, after the mobile platform obtains the lowest point cloud density of the lidar point cloud in the survey area operation, the lowest point cloud density is displayed on the user interface of the mobile platform, so that the user can intuitively Knowing the minimum point cloud density of the point cloud of the lidar obtained by the movable platform in the survey area, it is possible to know whether the operation requirements are met.

In some embodiments, obtain the lowest point cloud density of the lidar point cloud obtained by the movable platform in the survey area, and also obtain a preset lowest point cloud density, where the preset lowest point cloud density is the lowest point cloud density that meets the operational requirements Point cloud density, when the minimum point cloud density is less than the preset minimum point cloud density, it does not meet the job requirements. It should be noted that the preset minimum point cloud density can be flexibly set according to the actual situation, which is not specifically limited here.

Compare the lowest point cloud density of the point cloud of the lidar obtained by the calculated movable platform in the survey area with the preset lowest point cloud density, and judge that the calculated movable platform is in the survey area to obtain the laser light. Whether the minimum point cloud density of the radar's point cloud is less than the preset minimum point cloud density.

Exemplarily, calculate the ratio m between the preset minimum point cloud density and the minimum point cloud density of the lidar point cloud obtained by the movable platform in the survey area. If m is greater than or equal to 1, then the calculated movable platform The lowest point cloud density of the lidar point cloud obtained in the survey area is less than the preset lowest point cloud density; on the contrary, if m is less than 1, the calculated movable platform can obtain the lidar in the survey area. The minimum point cloud density of the point cloud is not less than the preset minimum point cloud density.

It should be noted that, it is also possible to compare the lowest point cloud density of the point cloud of the lidar obtained by the calculation of the movable platform in the survey area with the preset lowest point cloud density, and judge that the calculated value is acceptable. The mobile platform operates in the survey area to obtain whether the lowest point cloud density of the point cloud of the lidar is less than the preset lowest point cloud density.

If the calculated minimum point cloud density of the lidar point cloud obtained by the movable platform in the survey area is not less than the preset minimum point cloud density, that is to say, it meets the operation requirements, the movable platform and lidar are controlled according to the The target motion parameters and target scan parameters work in the survey area to obtain the corresponding point cloud.

If the calculated minimum point cloud density of the lidar point cloud obtained by the movable platform in the survey area is less than the preset minimum point cloud density, which means that it does not meet the operation requirements, adjust the target motion parameters and target scanning parameters , and recalculate the lowest point cloud density of the obtained point cloud, so that the re-obtained lowest point cloud density is not less than the preset lowest point cloud density.

In some embodiments, if the calculated minimum point cloud density of the lidar point cloud obtained by the movable platform in the survey area is less than the preset minimum point cloud density, prompt information is output. The prompt information includes, but is not limited to, voice prompt information, text prompt information, and the like. For example, corresponding text prompt information is displayed on the user interface of the movable platform. After receiving the prompt information, the user can perform a response operation in time and feedback corresponding adjustment instructions. Responding to the user's adjustment instruction based on the prompt information, and adjusting the target motion parameters and target scan parameters according to the adjustment instructions, so as to recalculate and obtain the lowest point cloud density based on the adjusted target motion parameters and target scan parameters.

In some embodiments, adjusting the target motion parameters and the target scan parameters may include: displaying a drop-down list of the target motion parameters and the target scan parameters; the drop-down list includes various parameter options corresponding to the target motion parameters and the target scan parameters; receiving A parameter option selected by the user based on the drop-down list; the parameter corresponding to a parameter option is adjusted.

In order to further improve the user's interactive experience, when the calculated minimum point cloud density of the lidar point cloud obtained by the movable platform in the survey area is less than the preset minimum point cloud density, the target motion parameters and target scanning parameters are displayed. drop-down list. For example, a drop-down list of target motion parameters and target scan parameters is displayed on the user interface of the movable platform. Among them, the drop-down list contains various parameter options corresponding to the target motion parameters and target scanning parameters, including but not limited to the distance parameter options between the movable platform and the survey area, the moving speed parameter options of the movable platform, and the movable platform movement parameter options. Route overlap rate parameter options, laser emission frequency parameter options, scan mode parameter options, scan frame rate parameter options, etc. The user can select one of the parameter options in the drop-down list, for example, select the laser emission frequency parameter option and the moving speed parameter option of the movable platform in the drop-down list. A parameter option selected by the user based on the drop-down list is received, and a parameter corresponding to the one parameter option selected by the user is adjusted. For example, if the user selects the laser emission frequency parameter option and the moving speed parameter option of the movable platform, the laser emission frequency and the moving speed of the movable platform are adjusted.

In other embodiments, the parameter priorities of the target motion parameters and the target scan parameters are preset. Exemplarily, the parameter priorities of the set target motion parameters and target scanning parameters are in descending order: the priority of the laser emission frequency of the lidar, the priority of the overlapping rate of the moving route of the movable platform, the priority of the movable The priority of the moving speed of the platform and the priority of the distance between the movable platform and the survey area. That is, the priority of the laser emission frequency>the priority of the overlapping rate of the moving route of the movable platform>the priority of the moving speed of the movable platform>the priority of the distance between the movable platform and the survey area.

Adjusting the target motion parameter and the target scanning parameter may include: acquiring the target motion parameter and the parameter priority of the target scanning parameter; and adjusting the target motion parameter and the target scanning parameter according to the parameter priority.

Unlike the target motion parameters and target scan parameters that are manually selected and adjusted by the user, the target motion parameters and target scan parameters are automatically adjusted based on the parameter priorities by acquiring preset parameter priorities of the target motion parameters and target scan parameters.

In some embodiments, according to the parameter priority, adjusting the target motion parameter and the target scanning parameter may include: adjusting the laser emission frequency of the lidar; based on the adjusted laser emission frequency of the lidar, the movable platform and the measurement The distance of the zone, the moving speed of the movable platform and the overlapping rate of the moving route of the movable platform are used to determine the first point cloud density.

When the preset target motion parameters and target scanning parameters have the priority of the laser emission frequency > the priority of the overlapping rate of the moving route of the movable platform > the priority of the moving speed of the movable platform > the priority of the movable platform and the When specifying the priority of the distance of the survey area, according to the priority of this parameter, the laser emission frequency of the lidar is first adjusted. The laser emission frequency of lidar has a certain upper limit, which is determined by the lidar device itself, and the laser emission frequency of the adjusted lidar does not exceed the upper limit.

After adjusting the laser emission frequency, based on the adjusted laser emission frequency of the lidar, the distance between the original movable platform and the survey area, the moving speed of the movable platform and the overlapping rate of the moving route of the movable platform, the The lowest point cloud density of the point cloud is determined. For the convenience of description, the re-determined lowest point cloud density is hereinafter referred to as the first point cloud density.

If the first point cloud density is not less than the preset minimum point cloud density, which means that the operation requirements have been met, control the movable platform and lidar to operate in the survey area according to the adjusted target scanning parameters and target motion parameters to obtain corresponding points. cloud.

If the first point cloud density is less than the preset minimum point cloud density, it means that it still does not meet the operation requirements. At this time, the overlapping rate of the moving route of the movable platform is adjusted according to the priority of this parameter.

After adjusting the overlapping rate of the moving route of the movable platform, based on the laser emission frequency of the adjusted lidar, the overlapping rate of the adjusted moving route of the movable platform, and the distance between the original movable platform and the survey area, The moving speed of the movable platform re-determines the lowest point cloud density of the point cloud. For the convenience of description, the re-determined lowest point cloud density is hereinafter referred to as the second point cloud density.

If the second point cloud density is not less than the preset minimum point cloud density, which means that the operation requirements have been met, control the movable platform and lidar to operate in the survey area according to the adjusted target scanning parameters and target motion parameters to obtain corresponding points cloud.

If the second point cloud density is less than the preset minimum point cloud density, it means that it still does not meet the operation requirements. At this time, the moving speed of the movable platform is adjusted according to the priority of the parameter.

After adjusting the moving speed of the movable platform, based on the laser emission frequency of the adjusted lidar, the overlapping rate of the moving route of the adjusted movable platform, the moving speed of the adjusted movable platform, and the original movable platform For the distance from the survey area, the lowest point cloud density of the point cloud is re-determined. For the convenience of description, the re-determined lowest point cloud density is hereinafter referred to as the third point cloud density.

If the third point cloud density is not less than the preset minimum point cloud density, which means that the operation requirements have been met, control the movable platform and lidar to operate in the survey area according to the adjusted target scanning parameters and target motion parameters to obtain corresponding points. cloud.

If the third point cloud density is less than the preset minimum point cloud density, it means that it still does not meet the operation requirements. At this time, the distance between the movable platform and the survey area is adjusted according to the priority of the parameter.

After adjusting the distance between the movable platform and the survey area, based on the adjusted laser emission frequency of the lidar, the adjusted overlapping rate of the moving route of the movable platform, the adjusted moving speed of the movable platform, the adjusted The distance between the movable platform and the survey area is determined, and the lowest point cloud density of the point cloud is re-determined. For the convenience of description, the re-determined lowest point cloud density is hereinafter referred to as the fourth point cloud density.

If the fourth point cloud density is not less than the preset minimum point cloud density, which means that the operation requirements have been met, control the movable platform and lidar to operate in the survey area according to the adjusted target scanning parameters and target motion parameters to obtain corresponding points. cloud.

If the fourth point cloud density is less than the preset minimum point cloud density, it means that it still does not meet the job requirements. Exemplarily, the above parameters are adjusted again according to the parameter priority until the minimum point cloud density obtained by recalculation Less than the preset minimum point cloud density.

It should be noted that if the moving speed of the movable platform is too slow or the distance between the movable platform and the survey area is too low, although a high point cloud density can be achieved, it will lead to low efficiency during operation, which is inconsistent with the original intention of the user. Therefore, in practical applications, the upper limit value of the moving speed and height of the movable platform is set, and the user makes a trade-off according to the efficiency and point cloud density, and adjusts the moving speed and high. Exemplarily, if the lowest point cloud density still cannot meet the requirements at a lower moving speed and altitude, the overlapping rate of the moving routes of the movable platform can be increased.

Exemplarily, if the movable platform load is equipped with a visible light camera at the same time, and the ground resolution and overlap ratio of visible light data are required, the maximum moving speed of the movable platform (maximum moving speed = photo side length * (1-photo Overlap rate)/fastest photographing interval) and the maximum height of the movable platform (photograph ground resolution=pixel size*aircraft height/focal length) are determined. At the same time, the point cloud strength also determines the maximum height limit. The moving speed of the adjusted movable platform does not exceed the maximum moving speed, and the distance between the adjusted movable platform and the measurement area does not exceed the maximum height.

In the above embodiment, the target motion parameters of the movable platform in the survey area are obtained, and the target scanning parameters of the lidar mounted on the movable platform are obtained, and the target motion parameters of the movable platform and the target scanning parameters of the lidar are calculated. The point cloud density distribution of the lidar point cloud obtained by the movable platform in the survey area, that is, the point cloud density distribution is determined by comprehensively considering various factors such as the motion parameters of the movable platform and the scanning parameters of the lidar. The accuracy and reliability of obtaining the point cloud density distribution of the survey area are improved.

Please refer to FIG. 14. FIG. 14 is a schematic block diagram of a movable platform provided by an embodiment of the present application. As shown in FIG. 14 , the movable platform 300 includes a processor 301 and a memory 302, and the processor 301 and the memory 302 are connected through a bus, such as an I2C (Inter-integrated Circuit) bus.

Specifically, the processor 301 may be a micro-controller unit (Micro-controller Unit, MCU), a central processing unit (Central Processing Unit, CPU), or a digital signal processor (Digital Signal Processor, DSP) or the like.

Specifically, the memory 302 may be a Flash chip, a read-only memory (ROM, Read-Only Memory) magnetic disk, an optical disk, a U disk, a mobile hard disk, and the like.

Wherein, the processor is used for running the computer program stored in the memory, and implements the following steps when executing the computer program:

In some embodiments, the processor is further configured to:

acquiring preset point cloud distribution information of the lidar, where the preset point cloud distribution information is measured under preset motion parameters of the movable platform and preset scanning parameters of the lidar;

When the processor calculates the point cloud density distribution of the lidar point cloud obtained by the movable platform in the survey area operation according to the target motion parameter and the target scanning parameter, the processor is used for: accomplish:

obtaining a first numerical relationship between the target motion parameter and the preset motion parameter;

acquiring a second numerical relationship between the target scan parameter and the preset scan parameter;

According to the first numerical relationship, the second numerical relationship, and the preset point cloud distribution information, it is determined that the point cloud of the lidar point cloud obtained by the movable platform in the survey area is determined. density distribution.

In some embodiments, the processor is further configured to:

According to the distribution of the point cloud density, the lowest point cloud density of the point cloud of the lidar obtained by the movable platform in the survey area is determined.

In some embodiments, the target motion parameters include the distance between the movable platform and the survey area, the moving speed of the movable platform, and the overlap ratio of the moving routes of the movable platform.

In some embodiments, the target scanning parameters include laser emission frequency, scanning mode, and scanning frame rate of the lidar.

In some embodiments, when implementing the acquiring the first numerical relationship between the target motion parameter and the preset motion parameter, the processor is configured to:

Obtain the first ratio between the distance between the movable platform and the survey area in the target motion parameters and the reference height in the preset motion parameters;

When the processor realizes the obtaining of the second numerical relationship between the target scanning parameter and the preset scanning parameter, the processor is configured to realize:

obtaining a second ratio between the laser emission frequency of the laser radar in the target scanning parameters and the reference emission frequency in the preset scanning parameters;

The processor is implementing the process of determining that the movable platform operates in the survey area to obtain the lidar according to the first numerical relationship, the second numerical relationship, and the preset point cloud distribution information. The point cloud density distribution of the point cloud is used to achieve:

The movable platform is determined according to the first ratio, the second ratio, the reference point cloud density corresponding to the preset point cloud distribution information, and the moving speed of the movable platform in the target motion parameter The lowest point cloud density of the point cloud of the lidar is obtained in the survey area operation.

In some embodiments, the processor is further configured to:

In the user interface of the movable platform, the lowest point cloud density is displayed.

In some embodiments, the processor is further configured to:

Get the preset minimum point cloud density;

If the calculated minimum point cloud density is less than the preset minimum point cloud density, adjust the target motion parameters and the target scan parameters so that the minimum point cloud density is not less than the preset minimum point cloud density Cloud density.

In some embodiments, the processor is further configured to:

If the calculated minimum point cloud density is not less than the preset minimum point cloud density, the movable platform and the lidar are controlled in the survey area according to the target motion parameters and the target scanning parameters work to obtain the point cloud.

In some embodiments, when implementing the acquiring preset point cloud distribution information of the lidar, the processor is configured to implement:

acquiring the scanning range of the lidar and multiple overlapping rates of multiple routes of the movable platform;

According to the scanning range and the multiple overlapping ratios, determine the point cloud density of the overlapping area and the point cloud density of the non-overlapping area;

The preset point cloud distribution information is generated based on the point cloud density of the overlapping area and the point cloud density of the non-overlapping area.

In some embodiments, the processor, when implementing the acquiring the target motion parameters of the movable platform in the survey area, and acquiring the target scanning parameters of the lidar mounted on the movable platform, is configured to:

The target motion parameters and the target scan parameters input by the user on the user interface of the movable platform are received.

In some embodiments, the processor is further configured to:

If the calculated minimum point cloud density is less than the preset minimum point cloud density, output a prompt message;

In response to the user's adjustment instruction based on the prompt information, the target motion parameter and the target scan parameter are adjusted according to the adjustment instruction.

In some embodiments, when implementing the adjusting of the target motion parameter and the target scan parameter, the processor is configured to:

Displaying a drop-down list of the target motion parameters and the target scan parameters; the drop-down list includes various parameter options corresponding to the target motion parameters and the target scan parameters;

receiving a parameter option selected by the user based on the drop-down list;

A parameter corresponding to the one parameter option is adjusted.

obtaining the parameter priority of the target motion parameter and the target scan parameter;

The target motion parameter and the target scan parameter are adjusted according to the parameter priority.

In some embodiments, the order of priority of the parameters from high to low is: the priority of the laser emission frequency of the lidar, the priority of the overlapping rate of the moving route of the movable platform, the priority of the movable platform The priority of the moving speed of the platform and the priority of the distance between the movable platform and the survey area.

In some embodiments, when the processor adjusts the target motion parameter and the target scan parameter according to the parameter priority, the processor is configured to:

adjusting the laser emission frequency of the lidar;

Determine the first point based on the adjusted laser emission frequency of the lidar, the distance between the movable platform and the survey area, the moving speed of the movable platform, and the overlap rate of the moving route of the movable platform Cloud density.

In some embodiments, after implementing the determining the first point cloud density, the processor further implements:

If the first point cloud density is less than the preset minimum point cloud density, adjusting the overlap ratio of the moving route of the movable platform;

Based on the adjusted laser emission frequency of the lidar, the adjusted overlap rate of the moving route of the movable platform, the distance between the movable platform and the survey area, and the moving speed of the movable platform, determine Second point cloud density.

In some embodiments, after performing the determining of the second point cloud density, the processor further performs:

If the second point cloud density is less than the preset minimum point cloud density, adjusting the moving speed of the movable platform;

Based on the adjusted laser emission frequency of the lidar, the adjusted overlapping rate of the moving route of the movable platform, the adjusted moving speed of the movable platform, the distance between the movable platform and the survey area distance to determine the third point cloud density.

In some embodiments, after implementing the determining the third point cloud density, the processor further implements:

If the third point cloud density is less than the preset minimum point cloud density, adjusting the distance between the movable platform and the survey area;

Based on the adjusted laser emission frequency of the lidar, the adjusted overlap rate of the moving route of the movable platform, the adjusted moving speed of the movable platform, the adjusted movable platform and the The distance of the survey area to determine the fourth point cloud density.

The embodiments of the present application further provide a computer-readable storage medium, where the computer-readable storage medium stores a computer program, the computer program includes program instructions, and the processor executes the program instructions to implement the embodiments of the present application Provides the steps of the point cloud density determination method.

Wherein, the computer-readable storage medium may be an internal storage unit of the removable platform described in the foregoing embodiments, such as a hard disk or a memory of the removable platform. The computer-readable storage medium can also be an external storage device of the removable platform, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital) equipped on the removable platform , SD) card, flash memory card (Flash Card), etc.

According to the embodiments of the present invention, a point cloud density determination method, a movable platform and a computer-readable storage medium are provided. By obtaining the target motion parameters of the movable platform in the survey area, and obtaining the target scanning parameters of the lidar mounted on the movable platform, and according to the target motion parameters of the movable platform and the target scanning parameters of the lidar, the movable platform is calculated. The point cloud density distribution of the point cloud of the lidar is obtained by the surveying area operation, that is, the motion parameters of the movable platform and the scanning parameters of the lidar are comprehensively considered to determine the point cloud density distribution, thereby improving the acquisition and measurement performance. The accuracy and reliability of the point cloud density distribution in the area.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalents within the technical scope disclosed in the present application. Modifications or substitutions shall be covered by the protection scope of this application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

A method for determining point cloud density, characterized in that the method comprises:

acquiring the target motion parameters of the movable platform in the survey area, and acquiring the target scanning parameters of the lidar mounted on the movable platform;

According to the target motion parameter and the target scanning parameter, the point cloud density distribution of the point cloud of the lidar obtained by the movable platform in the survey area is calculated.
The method for determining point cloud density according to claim 1, wherein the method further comprises:

acquiring preset point cloud distribution information of the lidar, where the preset point cloud distribution information is measured under preset motion parameters of the movable platform and preset scanning parameters of the lidar;

The calculating the point cloud density distribution of the point cloud of the lidar obtained by the movable platform in the survey area according to the target motion parameter and the target scanning parameter, including:

obtaining a first numerical relationship between the target motion parameter and the preset motion parameter;

acquiring a second numerical relationship between the target scan parameter and the preset scan parameter;

According to the first numerical relationship, the second numerical relationship, and the preset point cloud distribution information, it is determined that the point cloud of the lidar point cloud obtained by the movable platform in the survey area is determined. density distribution.
The method for determining point cloud density according to claim 1, wherein the method further comprises:

According to the distribution of the point cloud density, the lowest point cloud density of the point cloud of the lidar obtained by the movable platform in the survey area is determined.
The method for determining a point cloud density according to claim 1, wherein the target motion parameters include the distance between the movable platform and the survey area, the moving speed of the movable platform, and the movement speed of the movable platform. The overlap ratio of moving routes.
The method for determining a point cloud density according to claim 1, wherein the target scanning parameters include a laser emission frequency, a scanning mode, and a scanning frame rate of the lidar.
The method for determining a point cloud density according to claim 2, wherein the acquiring the first numerical relationship between the target motion parameter and the preset motion parameter comprises:

Obtain the first ratio between the distance between the movable platform and the survey area in the target motion parameters and the reference height in the preset motion parameters;

The obtaining of the second numerical relationship between the target scan parameter and the preset scan parameter includes:

obtaining a second ratio between the laser emission frequency of the laser radar in the target scanning parameters and the reference emission frequency in the preset scanning parameters;

According to the first numerical relationship, the second numerical relationship, and the preset point cloud distribution information, it is determined that the movable platform operates in the survey area to obtain the point cloud of the lidar. Point cloud density distribution, including:

The movable platform is determined according to the first ratio, the second ratio, the reference point cloud density corresponding to the preset point cloud distribution information, and the moving speed of the movable platform in the target motion parameter The lowest point cloud density of the point cloud of the lidar is obtained in the survey area operation.
The point cloud density determination method according to claim 3 or 6, wherein the method further comprises:

In the user interface of the movable platform, the lowest point cloud density is displayed.
The point cloud density determination method according to claim 3 or 6, wherein the method further comprises:

Get the preset minimum point cloud density;

If the calculated minimum point cloud density is less than the preset minimum point cloud density, adjust the target motion parameters and the target scan parameters so that the minimum point cloud density is not less than the preset minimum point cloud density Cloud density.
The method for determining a point cloud density according to claim 8, wherein the method further comprises:

If the calculated minimum point cloud density is not less than the preset minimum point cloud density, the movable platform and the lidar are controlled in the survey area according to the target motion parameters and the target scanning parameters work to obtain the point cloud.
The method for determining a point cloud density according to claim 2, wherein the obtaining the preset point cloud distribution information of the lidar comprises:

acquiring the scanning range of the lidar and multiple overlapping rates of multiple routes of the movable platform;

According to the scanning range and the multiple overlapping ratios, determine the point cloud density of the overlapping area and the point cloud density of the non-overlapping area;

The preset point cloud distribution information is generated based on the point cloud density of the overlapping area and the point cloud density of the non-overlapping area.
The method for determining a point cloud density according to claim 1, wherein the acquiring the target motion parameters of the movable platform in the survey area, and acquiring the target scanning parameters of the lidar mounted on the movable platform, comprises:

The target motion parameters and the target scan parameters input by the user on the user interface of the movable platform are received.
The method for determining a point cloud density according to claim 8, wherein the method further comprises:

If the calculated minimum point cloud density is less than the preset minimum point cloud density, output a prompt message;

In response to the user's adjustment instruction based on the prompt information, the target motion parameter and the target scan parameter are adjusted according to the adjustment instruction.
point cloud density determination method according to claim 8, is characterized in that, described adjustment described target motion parameter and described target scanning parameter, comprise:

Displaying a drop-down list of the target motion parameters and the target scan parameters; the drop-down list includes various parameter options corresponding to the target motion parameters and the target scan parameters;

receiving a parameter option selected by the user based on the drop-down list;

A parameter corresponding to the one parameter option is adjusted.
The method for determining point cloud density according to claim 8, wherein the adjusting the target motion parameter and the target scanning parameter comprises:

obtaining the parameter priority of the target motion parameter and the target scan parameter;

The target motion parameter and the target scan parameter are adjusted according to the parameter priority.
The method for determining a point cloud density according to claim 14, wherein the order of the priority of the parameters from high to low is: the priority of the laser emission frequency of the lidar, the moving route of the movable platform The priority of the overlap rate, the priority of the moving speed of the movable platform, and the priority of the distance between the movable platform and the survey area.
The method for determining a point cloud density according to claim 15, wherein the adjusting the target motion parameter and the target scanning parameter according to the parameter priority comprises:

adjusting the laser emission frequency of the lidar;

Determine the first point based on the adjusted laser emission frequency of the lidar, the distance between the movable platform and the survey area, the moving speed of the movable platform, and the overlap rate of the moving route of the movable platform Cloud density.
The method for determining a point cloud density according to claim 16, wherein after the determining the first point cloud density, the method further comprises:

If the first point cloud density is less than the preset minimum point cloud density, adjusting the overlap ratio of the moving route of the movable platform;

Based on the adjusted laser emission frequency of the lidar, the adjusted overlap rate of the moving route of the movable platform, the distance between the movable platform and the survey area, and the moving speed of the movable platform, determine Second point cloud density.
The method for determining a point cloud density according to claim 17, wherein after determining the second point cloud density, the method further comprises:

If the second point cloud density is less than the preset minimum point cloud density, adjusting the moving speed of the movable platform;

Based on the adjusted laser emission frequency of the lidar, the adjusted overlapping rate of the moving route of the movable platform, the adjusted moving speed of the movable platform, the distance between the movable platform and the survey area distance to determine the third point cloud density.
The method for determining a point cloud density according to claim 18, wherein after determining the third point cloud density, the method further comprises:

If the third point cloud density is less than the preset minimum point cloud density, adjusting the distance between the movable platform and the survey area;

Based on the adjusted laser emission frequency of the lidar, the adjusted overlap rate of the moving route of the movable platform, the adjusted moving speed of the movable platform, the adjusted movable platform and the The distance of the survey area to determine the fourth point cloud density.
A movable platform, characterized in that, comprising:

memory for storing computer programs;

a processor for invoking a computer program in the memory to execute the point cloud density determination method according to any one of claims 1 to 19.
A storage medium, characterized in that, the storage medium is used for storing a computer program, and the computer program is loaded by a processor to execute the method for determining the density of a point cloud according to any one of claims 1 to 19.