Filtering method for lidar, terminal device and computer readable storage medium

Abstract

The application is suitable for the field of laser radar technology, and provides a filtering method of laser radar, a terminal device and a computer readable storage medium, which are applied to laser radar. The laser radar receives echo signals reflected by a probe and forms point cloud data. The point cloud data includes a plurality of reflection points arranged in a scanning order. The filtering method of the laser radar includes: for the i-th reflection point, if the (i-1)-th reflection point is a normal point, whether the i-th reflection point and the near neighbor point before the i-th reflection point have the same trend is judged; if the i-th reflection point and the near neighbor point before the i-th reflection point have different trends, whether the i-th reflection point is a radiation point is judged; if the i-th reflection point is a radiation point, the i-th reflection point is determined to be a tailing point, and the tailing point is filtered out. Through the above method, the filtering accuracy of the tailing point can be improved, and the ranging accuracy of the laser radar is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of laser radar, and particularly relates to a filtering method of a laser radar, a terminal device, and a computer readable storage medium. BACKGROUND

[0002] A laser radar system uses light pulses to measure the distance of an object based on the time of flight (TOF) of each light pulse. Since the laser emission is a light beam with a certain cross-sectional area, when a single laser beam is projected to a near object and a far object, trailing points are easily generated in the laser point cloud data, thereby causing ranging errors.

[0003] Currently, a judgment method based on the distance of a neighborhood is usually used to identify trailing points. Specifically, the distance difference between a to-be-detected reflection point and each neighborhood point thereof is calculated, and the number of distance differences that exceed a distance threshold is counted to determine whether the to-be-detected reflection point is a trailing point. However, sometimes the distance difference between a trailing point and a neighborhood point is not large, and some trailing points are easily identified as normal points, which is low in recognition accuracy, thereby affecting the ranging accuracy and the point cloud effect. SUMMARY

[0004] The embodiments of the present application provide a filtering method of a laser radar, a terminal device, and a computer readable storage medium, which can improve the filtering accuracy of trailing points, thereby improving the ranging accuracy of the laser radar.

[0005] In a first aspect, the embodiments of the present application provide a filtering method of a laser radar, applied to the laser radar, the laser radar receives a reflection echo signal of a detected object and forms point cloud data, the point cloud data includes a plurality of reflection points arranged in a scanning order, and the filtering method of the laser radar includes:

[0006] For the i-th reflection point, if the (i-1)-th reflection point is a normal point, it is determined whether the i-th reflection point and the near-neighbor points before the i-th reflection point have the same trend, wherein the near-neighbor points before the i-th reflection point include m reflection points before the i-th reflection point in the scanning order, and m is a positive integer;

[0007] If the i-th reflection point and the near-neighbor points before the i-th reflection point have different trends, it is determined whether the i-th reflection point is a radiation point, wherein the angle formed by the radiation point, the adjacent point of the radiation point, and the origin point exceeds a preset range, and the origin point represents the position of the laser radar;

[0008] If the i-th reflection point is a radiation point, it is determined that the i-th reflection point is a trailing point, and the trailing point is filtered out.

[0009] In the embodiments of the application, whether the current reflection point is normal is determined by judging whether the current reflection point and the previous adjacent point are of the same trend; if not, whether the current reflection point is a radiation point is further judged, and whether the abnormal reflection point is a tailing point or a misjudgment is further judged; that is, two times of judgment are performed, and the judgment accuracy is improved; in addition, through the same trend judgment, the misjudgment caused by a large distance between adjacent points is avoided, and the judgment accuracy is further improved. Through the above method, the filtering accuracy of the tailing point is effectively improved, and the ranging accuracy of the laser radar is improved.

[0010] In a possible implementation of the first aspect, the judging whether the i th reflection point and the adjacent point before the i th reflection point are of the same trend comprises:

[0011] determining a first index value according to a first distance between the i th reflection point and the origin and a second distance between the i-2 th reflection point and the origin;

[0012] obtaining a third distance between a middle point and the origin from a first preset table according to the first index value, the middle point being a midpoint of a line connecting the i th reflection point and the i-2 th reflection point;

[0013] if a fourth distance between the i-1 th reflection point and the origin is within a preset range of the third distance, it is determined that the i th reflection point and the adjacent point before the i th reflection point are of the same trend;

[0014] if the fourth distance between the i-1 th reflection point and the origin is not within the preset range of the third distance, it is determined that the i th reflection point and the adjacent point before the i th reflection point are not of the same trend.

[0015] In a possible implementation of the first aspect, the judging whether the i th reflection point is a radiation point comprises:

[0016] calculating a field angle of a line connecting the i th reflection point and the origin and a line connecting the origin and the i-1 th reflection point;

[0017] finding a length boundary value corresponding to the field angle in a second preset table;

[0018] calculating a length range according to a distance between the i-1 th reflection point and the origin and the length boundary value;

[0019] if a distance between the i th reflection point and the origin is not within the length range, it is determined that the i th reflection point is a radiation point;

[0020] If the distance between the i th reflection point and the origin is within the length range, it is determined that the i th reflection point is a non-radiation point.

[0021] In a possible implementation manner of the first aspect, before determining whether the i th reflection point and the adjacent point before the i th reflection point have the same trend, the method further includes:

[0022] If the i-1 th reflection point is a normal point, it is determined whether the i-2 th reflection point is a trailing point.

[0023] If the i-2 th reflection point is a trailing point, it is detected whether the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend.

[0024] If the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend, the i-2 th reflection point is corrected as a normal point.

[0025] In a possible implementation manner of the first aspect, the detection of whether the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend includes:

[0026] If the i-3 th reflection point, the i-2 th reflection point and the i-1 th reflection point have the same trend, and the i-2 th reflection point, the i-1 th reflection point and the i th reflection point have the same trend, it is determined that the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend.

[0027] In a possible implementation manner of the first aspect, the method further includes:

[0028] The plurality of reflection points in the point cloud data are traversed in the scanning order, and first labels of the plurality of reflection points are obtained, the first labels being used to indicate that a reflection point is a normal point or a trailing point.

[0029] The plurality of reflection points in the point cloud data are traversed in a reverse order of the scanning order, and second labels of the plurality of reflection points are obtained, the second labels being used to indicate that a reflection point is a normal point or a trailing point.

[0030] For each reflection point, if the first label and the second label of the reflection point both indicate a trailing point, it is determined that the reflection point is a trailing point.

[0031] If any one of the first label and the second label of the reflection point indicates a normal point, it is determined that the reflection point is a normal point.

[0032] In a possible implementation manner of the first aspect, after determining whether the i-th reflection point and the adjacent point before the i-th reflection point have the same trend, the method further includes:

[0033] If the i-th reflection point and the adjacent point before the i-th reflection point have the same trend, it is determined that the i-th reflection point is a normal point.

[0034] After determining whether the i-th reflection point is a radiation point, the method further includes:

[0035] If the i-th reflection point is not a radiation point, it is determined that the i-th reflection point is a normal point.

[0036] In a second aspect, an embodiment of the present application provides a filtering device of a laser radar, applied to the laser radar, the laser radar receives echo signals reflected by a detection object and forms point cloud data, the point cloud data includes a plurality of reflection points arranged in a scanning order, and the filtering device of the laser radar includes:

[0037] A first determining unit is configured to, for an i-th reflection point, if an (i-1)-th reflection point is a normal point, determine whether the i-th reflection point and an adjacent point before the i-th reflection point have the same trend, wherein the adjacent point before the i-th reflection point includes m reflection points before the i-th reflection point in the scanning order, and m is a positive integer.

[0038] A second determining unit is configured to, if the i-th reflection point and the adjacent point before the i-th reflection point have different trends, determine whether the i-th reflection point is a radiation point, wherein an angle formed by the radiation point, a neighboring point of the radiation point, and an original point exceeds a preset range, and the original point represents a position of the laser radar.

[0039] A result unit is configured to, if the i-th reflection point is a radiation point, determine that the i-th reflection point is a tailing point, and filter out the tailing point.

[0040] In a third aspect, an embodiment of the present application provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the filtering method of the laser radar according to any one of the first aspect.

[0041] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the filtering method of the laser radar according to any one of the first aspect.

[0042] In a fifth aspect, the embodiments of the present application provide a computer program product, which, when running on a terminal device, causes the terminal device to perform the filtering method of the laser radar according to any one of the first aspect.

[0043] It can be understood that the beneficial effects of the second aspect to the fifth aspect can be referred to the related description in the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0045] Figure 1 is a schematic diagram of the laser ranging principle provided by the embodiments of the present application;

[0046] Figure 2 is a schematic diagram of the tailing phenomenon provided by the embodiments of the present application;

[0047] Figure 3 is a flowchart of the filtering method of the laser radar provided by the embodiments of the present application;

[0048] Figure 4 is a schematic diagram of the same trend provided by the embodiments of the present application;

[0049] Figure 5 is a schematic diagram of the trend judgment principle provided by the embodiments of the present application;

[0050] Figure 6 is a schematic diagram of the tailing point and the radiation point provided by the embodiments of the present application;

[0051] Figure 7 is a schematic diagram of the radiation point judgment principle provided by the embodiments of the present application;

[0052] Figure 8 is a schematic diagram of the tailing point identification flow provided by the embodiments of the present application;

[0053] Figure 9 is a schematic diagram of the reflection point provided by the embodiments of the present application;

[0054] Figure 10 is a schematic diagram of the reflection point provided by another embodiment of the present application;

[0055] Figure 11 is a schematic diagram of the tailing point identification flow provided by another embodiment of the present application;

[0056] Figure 12 is a structural block diagram of a filtering device of a laser radar provided by an embodiment of the present application;

[0057] Figure 13 is a structural schematic diagram of a terminal device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0058] In the following description, specific details are set forth, such as particular system configurations, techniques, etc., in order to provide a thorough understanding of embodiments of the present application. However, persons having ordinary skill in the art will readily understand that embodiments of the present application can be practiced without these specific details. In other instances, well-known structures, devices, circuits, and materials have not been described in detail in order to avoid obscuring the description of the present application.

[0059] It should be understood that the term "comprises" when used in this specification and the appended claims, specifies the presence of stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0060] It should also be understood that the term "and / or" when used in this specification and the appended claims, means any one or more of the associated listed items can be present, and includes multiples of any one or more of the associated listed items.

[0061] As used in this specification and the appended claims, the term "if" can be interpreted as meaning "when" or "once" or "in response to a determination" or "in response to detecting" depending on the context. Similarly, the phrase "if it is determined" or "if [a described condition or event] is detected" can be interpreted as meaning "once it is determined" or "in response to a determination" or "once [the described condition or event] is detected" or "in response to detecting [a described condition or event]" depending on the context.

[0062] In addition, the terms "first", "second", "third", etc. are used herein only to distinguish one element from another, and do not imply or suggest a relative importance of the elements so designated.

[0063] The terms "one embodiment", "some embodiments", "an embodiment", "some embodiments", "another embodiment", "certain embodiments", etc., as used in this specification, mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in one embodiment", "in some embodiments", "in other embodiments", "in some other embodiments", etc., in various places in this specification are not necessarily all referring to the same embodiment, unless otherwise specifically noted.

[0064] First, let's introduce the technical background involved in the embodiments of this application.

[0065] LiDAR systems use light pulses to measure the distance to an object based on the time-of-flight (TOF) of each pulse. See also Figure 1 This is a schematic diagram illustrating the laser ranging principle provided in an embodiment of this application. Figure 1 As shown, a lidar system measures distance by emitting a laser beam and receiving the laser signal reflected back from the target object. Let the laser emission time be T1 and the echo reception time be T2. After aligning the echo times of different energies and eliminating non-spatial propagation delays ΔT due to hardware limitations, the actual target distance can be obtained. Where c is the speed of light.

[0066] However, because laser emission is a beam, its cross-section has a certain area. See also Figure 2 This is a schematic diagram illustrating the trailing phenomenon provided in an embodiment of this application. For example... Figure 2 As shown in (a), when a single laser beam strikes an object at a distance, an irregular echo will appear, causing timing errors and thus ranging errors. Figure 2 As shown in (b) above, P i The point is the trailing point generated by the above situation.

[0067] In related technologies, one method for detecting trailing points is a neighborhood distance-based judgment method. This type of method calculates the distance differences between the reflection point to be measured and each of its neighboring points, counts the number of distance differences exceeding a distance threshold, and uses this count to determine whether the reflection point to be measured is a trailing point. For example, assuming a neighborhood of 3, if the calculated distance differences d1 and d2 between the reflection point to be measured and its two adjacent points are both greater than the threshold d, then the point to be measured is considered a trailing point. However, in practical applications, sometimes the distance differences between the trailing point and its neighboring points are not large, making it easy to identify some trailing points as normal points, resulting in low recognition accuracy and affecting ranging accuracy and point cloud effects.

[0068] Another method for detecting trailing points is based on neighborhood angle judgment. This type of method identifies trailing points by determining whether the angle formed by the reflection point to be measured, its nearest neighbors, and the origin exceeds the normal angular range. For example, ... Figure 2 As shown in (b) above, if P i Let be the reflection point to be measured. If ∠oP i P i+1 If the angle is greater than 175° or less than 5°, then P is considered to be... i This refers to the tailing point. Due to the involvement of geometric calculations, this type of method requires a large amount of data processing; furthermore, when there are... Figure 2 When dealing with large-angle reflection points as shown, this type of method is prone to misidentifying large-angle reflection points as trailing points, resulting in low detection accuracy and thus affecting the ranging accuracy.

[0069] To solve the above problems, the embodiment of the present application provides a filtering method of a laser radar. Through the method in the embodiment of the present application, the missed detection caused by the small distance difference between the tailing point and the neighborhood point can be avoided, and the misjudgment of the large oblique angle reflection point can also be avoided, thereby effectively improving the filtering precision of the tailing point and the ranging precision of the laser radar. Meanwhile, through the preset table, the calculation amount of the algorithm is reduced, the detection efficiency is effectively improved, and the ranging time of the laser radar is saved.

[0070] Referring to Figure 3 , it is a flowchart of the filtering method of the laser radar provided by the embodiment of the present application. The filtering method of the laser radar provided by the embodiment of the present application is applied to a laser radar, the laser radar receives echo signals reflected by a probe and forms point cloud data, and the point cloud data includes a plurality of reflection points arranged in a scanning order.

[0071] In some application scenarios, the laser radar is a multi-line radar. In this scenario, the point cloud generated by each line laser needs to be filtered. Correspondingly, the method provided in the embodiment of the present application is a processing method for the point cloud data generated by a line laser.

[0072] By way of example, and without limitation, the method can include the following steps:

[0073] S301, for the i-th reflection point, if the (i-1)-th reflection point is a normal point, it is judged whether the i-th reflection point and the near-neighbor point before the i-th reflection point have the same trend.

[0074] The near-neighbor point before the i-th reflection point includes m reflection points before the i-th reflection point in the scanning order, and m is a positive integer. For example, when m=2, the near-neighbor point before the i-th reflection point is the (i-1)-th reflection point and the (i-2)-th reflection point.

[0075] In the embodiment of the present application, if a reflection point and its two previous near-neighbor points are on the same straight line (or approximate straight line), it means that the reflection point and its two previous near-neighbor points have the same trend. Referring to Figure 4 , it is a schematic diagram of the same trend provided by the embodiment of the present application. When ∠P i P i-2 P i-1 is greater than the threshold angle (set as θ thd ), it is considered that P i is different from P i-2 P i-1 has the same trend, otherwise, it is considered that P i is different from P i-2 P i-1 has the same trend. As shown in (a) of Figure 4 , θ is greater than θthd That is, P i With P i-2 P i-1 The trends are different. For example... Figure 4 As shown in (b), θ is less than θ thd That is, P i With P i-2 P i-1 The trend is the same.

[0076] In one embodiment, see Figure 5 This is a schematic diagram illustrating the trend judgment principle provided in the embodiments of this application. Figure 5 As shown, P i-2 and P i Let P be the distance between points, α be the radar horizontal resolution angle, and P be the distance between points. i-1 In the ray OP c Based on the sine and cosine laws, OP can be easily calculated. c The length of is denoted as R(P). c Let T be the threshold for the difference in diameters along the same trend (e.g., 0.05), then we can obtain:

[0077] R(P cl )=R(P c )×(1-T)

[0078] R(P ch )=R(P c )×(1+T)

[0079] If the midpoint P i-1 Radial length R(P) i-1 ) satisfies: R(P cl ) <R(P i-1 ) <R(P ch If P is considered to be true, then P is considered to be true. i-2 ,P i-1 ,P i It is the same trend, in other words, P i relative to the previous nearest normal point P i-2 ,P i-1 The changing trend and P i-2 ,P i-1 The extension trends of the points are basically the same.

[0080] In the above embodiments, real-time calculation is time-consuming. To address this issue, in another embodiment, the trend determination method may include:

[0081] The first index value is determined based on the first distance between the i-th reflection point and the origin, and the second distance between the (i-2)-th reflection point and the origin;

[0082] According to the first index value, a third distance between an intermediate point and the original point is obtained from a first preset table, the intermediate point being a midpoint of a line connecting the ith reflection point and the i-2th reflection point;

[0083] If a fourth distance between the i-1th reflection point and the original point is within a preset range of the third distance, it is determined that the ith reflection point has the same trend as a neighboring point before the ith reflection point.

[0084] If the fourth distance between the i-1th reflection point and the original point is not within the preset range of the third distance, it is determined that the ith reflection point has a different trend from the neighboring point before the ith reflection point.

[0085] For example, let R(P i-2 ) = 1, and limit 0.50 < R(P i ) / R(P i-2 )<1.50 (this condition can be met in most cases, and if not met, the same trend determination is not performed), and R(P i ) / R(P i-2 ) granularity is 0.01, that is, 100 pairs of R(P i ) / R(P i-2 ) are selected to calculate the R(P c ) result. Accordingly, K = int(100 x R(P i ) / R(P i-2 ))-50 is taken as the index value (0-100), and the array value is the corresponding R(P c ) value. Thus, the R(P c ) lookup table is established, and subsequently the corresponding R(P c ) value can be quickly obtained according to the actual K value.

[0086] Through the lookup table calculation method in the embodiments of the present application, the calculation amount of trend determination can be reduced, and the efficiency of trend determination can be improved, thereby improving the efficiency of tail recognition.

[0087] S302, if the ith reflection point has a different trend from a neighboring point before the ith reflection point, it is determined whether the ith reflection point is a radiation point.

[0088] The angle formed by the radiation point, the adjacent point of the radiation point, and the original point exceeds a preset range, and the original point represents the position of the laser radar.

[0089] In the embodiments of the present application, if a reflection point is a radiation point, and the reflection point and the non-radiation points in the two fields are not on the same straight line (or approximate straight line), it is considered that the reflection point is a tail point. Referring to Figure 6 , which is a schematic diagram of a tail point and a radiation point provided by the embodiments of the present application. As shown inFigure 6 As shown, the right radiation point is considered to be on the same straight line, so it should not be mistaken for a trailing point. The left radiation point is not on the same straight line with its neighborhood points, so these radiation points are trailing points.

[0090] In an embodiment, referring to Figure 7 , it is a schematic diagram of the radiation point judgment principle provided by the embodiment of the present application. As shown in (a) of Figure 7 , the method for judging whether P1 is a radiation point is: whether ∠OP1P2 is within a threshold angle range (for example: 5°-175°), if not, it is considered to be a radiation point. However, according to OP1 length R1, OP2 length R2 and angle θ1, the angle ∠OP1P2 (set as θ2) needs to be calculated, which needs to use the cosine theorem and the sine theorem. For FPGA and other hardware, the calculation is relatively complex and consumes more resources, which is not suitable for real-time calculation of θ2 value.

[0091] In order to solve the above problems, a lookup table can be used for fast judgment. In another embodiment, the radiation point judgment method comprises: calculating the domain angle of the line between the i-th reflection point and the origin and the line between the origin and the i-1-th reflection point; looking up the length boundary value corresponding to the domain angle in a second preset table; calculating the length range according to the distance between the i-1-th reflection point and the origin and the length boundary value; if the distance between the i-th reflection point and the origin is not within the length range, it is determined that the i-th reflection point is a radiation point; if the distance between the i-th reflection point and the origin is within the length range, it is determined that the i-th reflection point is a non-radiation point.

[0092] As shown in (b) of Figure 7 , let R1=1, because the radar unit rotation angle θ and the threshold angles θ2 and θ3 are fixed, and point P2 is a neighborhood point of P1 (the neighborhood size is set in advance, assuming that the neighborhood size is 5, i.e. two points on the left and right of P1), then θ1 is θ or 2θ, so the length R thd1 of OP3 and the length R thd2 of OP4 can be calculated. thd1 If the amplitude R2 of the point cloud point P2 satisfies: R thd2 <R2<R thd1 , it is determined to be a non-radiation point, otherwise it is a radiation point.

[0093] Store the corresponding relationship between all neighborhood angles θ1 (discrete and finite, multiples of θ) and corresponding R thd2 and R thd1 in a table, then R thd2 and R thd1, R' thd2 :

[0094] R' thd1 = R thd1 x R'1

[0095] R' thd2 = R thd2 x R'1

[0096] Then, it is judged whether the actual length R'2 of OP2 satisfies: R' thd1 <R'2<R' thd2 . Further, it is judged whether it is a radiation point.

[0097] Through the table lookup calculation method of the embodiments of the present application, the calculation amount of the radiation point judgment can be reduced, the efficiency of the radiation point judgment can be improved, and thus the efficiency of the tail recognition can be improved.

[0098] In S303, if the i-th reflection point is a radiation point, it is determined that the i-th reflection point is a tail point, and the tail point is filtered out.

[0099] In the above embodiments, i is an integer greater than 1.

[0100] In an embodiment, when i = 1, that is, for the first reflection point, it is first judged whether the first reflection point is a radiation point; if yes, it is determined that the first reflection point is a tail point; if no, it is determined that the first reflection point is a normal point.

[0101] In the embodiments of the present application, it is first determined whether the current reflection point is normal by judging whether the current reflection point and the previous adjacent point are of the same trend; if not, it is further judged whether the current reflection point is a radiation point, and it is further judged whether the abnormal reflection point is a tail point or a misjudgment; that is, two judgments are performed, and the judgment accuracy is improved; in addition, through the same trend judgment, the misjudgment caused by a large distance between adjacent points is avoided, and the judgment accuracy is further improved. Through the above method, the filtering accuracy of the tail point is effectively improved, and thus the ranging accuracy of the laser radar is improved.

[0102] Referring to Figure 8 , FIG. 1 is a tail point recognition flowchart provided by the embodiments of the present application. As shown in Figure 8As shown, for the point cloud data generated for each line laser, starting from the selected initial point, each point is traversed in clockwise direction in turn. Radiation point judgment is performed on the initial point (i.e. the first reflection point). If the initial point is a radiation point, the initial point is marked as a tailing point; if the initial point is a non-radiation point, the initial point is marked as a normal point. Next, the next point (i.e. the second reflection point) is judged. For the second reflection point, if the previous point (i.e. the first reflection point) is a tailing point, it is judged whether the second reflection point is a radiation point. If the second reflection point is a radiation point, the second reflection point is marked as a tailing point; if the second reflection point is not a radiation point, the second reflection point is marked as a normal point. If the previous point (i.e. the first reflection point) is a normal point, it is judged whether the second reflection point and the previous near neighbor point have the same trend. If the trend is the same, the second reflection point is considered to be in the same plane as the normal point, and is marked as a normal point; if the trend is different, it is judged whether the second reflection point is a radiation point. If the second reflection point is a radiation point, the second reflection point is marked as a tailing point; if the second reflection point is not a radiation point, the second reflection point is marked as a normal point. In turn, until the last reflection point is traversed.

[0103] In some application scenarios, referring to Figure 9 , a schematic diagram of a reflection point is provided. As shown in Figure 9 , (a) shows a case of traversing (clockwise scanning) the reflection points in the scanning order. In this case, when traversing the large-angle plane from near to far (distance from the origin), the far radiation point P i to P i+2 will be determined as a normal point because the far radiation point has the same trend as the previous near non-radiation (i.e. normal point). When turning into the large-angle plane from the far inflection point, the near radiation point P j to P j+2 will be determined as a tailing point because the near radiation point is a radiation point and has a different trend from the previous normal point. Figure 9 , (b) shows a case of traversing the reflection points in the reverse order of the scanning order (counterclockwise scanning). In this case, when traversing the large-angle plane from near to far (distance from the origin), the far radiation point P' j to P' j+2 will be determined as a normal point; when turning into the large-angle plane from the far inflection point, the near radiation point P' i+1 and P' i+2 will be determined as tailing points.

[0104] As shown in Figure 9In the case shown, the one-way traversal of the single side trend judgment will still cause some cases of large angle points to be misjudged as trailing points. In order to solve the misjudgment problem, the trend judgment needs to be performed on both sides of the continuous reflection point set to determine whether the reflection point set is a trailing point set. Only when both sides are not the same trend, it is considered that the reflection point set is a trailing point set. The following two ways are provided in the embodiments of the present application.

[0105] One way is to traverse the plurality of reflection points in the point cloud data according to the scanning order to obtain a first mark of each of the plurality of reflection points, the first mark being used to indicate that the reflection point is a normal point or a trailing point; traverse the plurality of reflection points in the point cloud data according to the reverse order of the scanning order to obtain a second mark of each of the plurality of reflection points, the second mark being used to indicate that the reflection point is a normal point or a trailing point; for each reflection point, if the first mark and the second mark of the reflection point both indicate a trailing point, the reflection point is determined to be a trailing point; if any one of the first mark and the second mark of the reflection point indicates a normal point, the reflection point is determined to be a normal point.

[0106] In the above-mentioned way, it is equivalent to performing forward and reverse traversal twice, and only when it is determined to be a trailing point at the same time, it is determined to be a trailing point. For example, in forward traversal, the trailing point can be marked as 1, and the normal point can be marked as 0; in reverse traversal, the trailing point is also marked as 1, and the normal point is marked as 0. Then, the AND operation result of the two marks corresponding to each reflection point is judged: if it is 1 (i.e., both are marked as trailing points), the reflection point is marked as a trailing point; if it is 0 (i.e., not all are marked as trailing points or none are marked as trailing points), the reflection point is marked as a normal point.

[0107] Another way is that if the i-1th reflection point is a normal point, it is determined whether the i-2th reflection point is a trailing point; if the i-2th reflection point is a trailing point, it is detected whether the i-1th reflection point and the neighboring point before the i-1th reflection point have the same trend; if the i-1th reflection point and the neighboring point before the i-1th reflection point have the same trend, the i-2th reflection point is corrected to be a normal point.

[0108] Specifically, if the i-3th reflection point, the i-2th reflection point and the i-1th reflection point have the same trend, and the i-2th reflection point, the i-1th reflection point and the i-th reflection point have the same trend, it is determined that the i-1th reflection point and the neighboring point before the i-1th reflection point have the same trend.

[0109] For example, referring to Figure 10 is a schematic diagram of a reflection point provided by another embodiment of the present application. P j is a reflection point, but different from the normal point P j-2 and P j-1The trend is the same, so it is believed that P j Normal. (P) j+1 Let P be the radiating point and the normal point. j-1 and P j Different trends, therefore marked P j+1 This is the trailing point. Because P j+1 P is the trailing point. j+2 Since it is a radiation point, it is labeled P. j+2 P is the trailing point. j+3 For normal points, the previous point P j+2 As the tailing point, P needs to be adjusted. j+2 Perform subsequent trend detection (i.e., determine P) j+3 (Whether it follows the same trend as its previous nearest neighbors):

[0110] Condition 1: Normal point P j+3 and trailing point P j+1 P j+2 Same trend;

[0111] Condition 2: Normal point P j+4 and trailing point P j+2 And normal point P j+3 Same trend;

[0112] If both conditions are met, then the preceding trailing point P can be considered as... j+1 P j+2 and subsequent normal point P j+3 P j+4 Since they are in the same plane, P j+2 Change it to a normal point. If both conditions one and two are not met simultaneously, the original trailing point mark will not be modified.

[0113] In some application scenarios, it can also be combined with P j+2 Modify a continuous set of trailing points into normal points. For example... Figure 10 As shown, P j+1 and P j+2 A continuous set of trailing points is formed in P. j+2 Under the above two conditions, P j+1 and P j+2 All have been corrected to normal.

[0114] See Figure 11 This is a schematic diagram of a trailing point identification process provided in another embodiment of this application. Figure 11 As shown, for the point cloud data generated by each laser line, starting from the selected initial point, each point is traversed sequentially in a clockwise direction. The initial point (i.e., the first reflection point) is judged as a radiating point; if it is a radiating point, it is marked as a trailing point; if it is a non-radiating point, it is marked as a normal point. Then, the next point (the second reflection point) is judged.

[0115] For the i-th (i>3) reflection point, if the previous point (i.e. the (i-1)-th reflection point) is a trailing point, it is determined whether the i-th reflection point is a radiation point, if the i-th reflection point is a radiation point, the i-th reflection point is marked as a trailing point; if the i-th reflection point is not a radiation point, the i-th reflection point is marked as a normal point.

[0116] If the previous point (i.e. the (i-1)-th reflection point) is a normal point, it is determined whether the (i-1)-th reflection point and the previous reflection point have the same trend; if the trends are the same, the (i-1)-th reflection point is modified as a normal point; if the trends are different, it is determined whether the i-th reflection point and the previous adjacent point have the same trend; if the trends are the same, the i-th reflection point is marked as a normal point; if the trends are different, it is determined whether the i-th reflection point is a radiation point; if it is a radiation point, the i-th reflection point is marked as a trailing point; if it is not a radiation point, the i-th reflection point is marked as a normal point. In succession, until the last reflection point is traversed.

[0117] Through the above embodiment, the reflection points are determined by bilateral same trend, only when the current reflection point has different trends on both sides, the current reflection point is considered as a trailing point. Through the above method, the misjudgment caused by unilateral same trend determination is effectively avoided, the accuracy of trailing point identification is effectively improved, and the accuracy of radar ranging is improved.

[0118] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, the execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0119] Corresponding to the filtering method of the laser radar described in the above embodiment, Figure 12 is a structural block diagram of a filtering device of a laser radar provided by the embodiments of the present application, only the parts related to the embodiments of the present application are shown for the convenience of description.

[0120] Referring to Figure 12 , the device comprises:

[0121] The first determining unit 121 is configured to, for the i-th reflection point, if the (i-1)-th reflection point is a normal point, determine whether the i-th reflection point and the adjacent point before the i-th reflection point have the same trend, wherein the adjacent point before the i-th reflection point includes m reflection points in the scanning order before the i-th reflection point, and m is a positive integer.

[0122] The second judging unit 122 is configured to judge whether the ith reflection point is a radiation point if the ith reflection point is different from the trend of the adjacent point before the ith reflection point, wherein an angle formed by the radiation point, a neighboring point of the radiation point and an original point exceeds a preset range, and the original point represents a position of the laser radar.

[0123] The result unit 123 is configured to determine that the ith reflection point is a tailing point and filter out the tailing point if the ith reflection point is the radiation point.

[0124] Optionally, the first judging unit 121 is further configured to:

[0125] determine a first index value according to a first distance between the ith reflection point and the original point and a second distance between an i-2th reflection point and the original point;

[0126] obtain a third distance between an intermediate point and the original point from a first preset table according to the first index value, wherein the intermediate point is a midpoint of a line connecting the ith reflection point and the i-2th reflection point;

[0127] determine that the ith reflection point is the same as the trend of the adjacent point before the ith reflection point if a fourth distance between an i-1th reflection point and the original point is within a preset range of the third distance;

[0128] determine that the ith reflection point is different from the trend of the adjacent point before the ith reflection point if the fourth distance between the i-1th reflection point and the original point is not within the preset range of the third distance.

[0129] Optionally, the second judging unit 122 is further configured to:

[0130] calculate a field angle of a line connecting the ith reflection point and the original point and a line connecting the original point and the i-1th reflection point;

[0131] find a length boundary value corresponding to the field angle in a second preset table;

[0132] calculate a length range according to a distance between the i-1th reflection point and the original point and the length boundary value;

[0133] determine that the ith reflection point is the radiation point if a distance between the ith reflection point and the original point is not within the length range;

[0134] determine that the ith reflection point is a non-radiation point if the distance between the ith reflection point and the original point is within the length range.

[0135] Optionally, the device 12 further comprises:

[0136] The double-side detection unit 124 is configured to, before judging whether the i th reflection point and the adjacent point before the i th reflection point have the same trend, judge whether the i-2 th reflection point is a trailing point if the i-1 th reflection point is a normal point; if the i-2 th reflection point is a trailing point, judge whether the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend; and if the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend, correct the i-2 th reflection point as a normal point.

[0137] Optionally, the double-side detection unit 124 is further configured to, if the i-3 th reflection point, the i-2 th reflection point and the i-1 th reflection point have the same trend, and the i-2 th reflection point, the i-1 th reflection point and the i th reflection point have the same trend, judge that the i-1 th reflection point and the adjacent point before the i-1 th reflection point have the same trend.

[0138] Optionally, the double-side detection unit 124 is configured to traverse the plurality of reflection points in the point cloud data according to a scanning order to obtain a first mark of each of the plurality of reflection points, the first mark being used to indicate whether the reflection point is a normal point or a trailing point; traverse the plurality of reflection points in the point cloud data according to a reverse order of the scanning order to obtain a second mark of each of the plurality of reflection points, the second mark being used to indicate whether the reflection point is a normal point or a trailing point; and for each reflection point, if the first mark and the second mark of the reflection point both indicate a trailing point, judge that the reflection point is a trailing point; and if either of the first mark and the second mark of the reflection point indicates a normal point, judge that the reflection point is a normal point.

[0139] Optionally, the first judging unit 121 is further configured to, if the i th reflection point and the adjacent point before the i th reflection point have the same trend, judge that the i th reflection point is a normal point.

[0140] Optionally, the second judging unit 122 is further configured to, if the i th reflection point is a non-radiation point, judge that the i th reflection point is a normal point.

[0141] It should be noted that the information interaction and execution process between the above apparatuses / units are based on the same concept as the method embodiments, and the specific functions and technical effects thereof can be referred to the method embodiments, which will not be described here.

[0142] In addition, Figure 12The filtering device shown can be a software unit, a hardware unit, or a combination of software and hardware built into an existing terminal device, or it can be integrated into the terminal device as an independent component, or it can exist as an independent terminal device.

[0143] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0144] Figure 13 This is a schematic diagram of the structure of the terminal device provided in the embodiments of this application. For example... Figure 13 As shown, the terminal device 13 of this embodiment includes: at least one processor 130 ( Figure 13 (Only one is shown) a processor, a memory 131, and a computer program 132 stored in the memory 131 and executable on the at least one processor 130, wherein the processor 130 executes the computer program 132 to implement the steps in the filtering method embodiments of any of the above-described lidars.

[0145] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. This terminal device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that... Figure 13 This is merely an example of terminal device 13 and does not constitute a limitation on terminal device 13. It may include more or fewer components than shown, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0146] The processor 130 can be a central processing unit (CPU), and can also be other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or the like. The general-purpose processor can be a microprocessor or the like.

[0147] The memory 131 can be an internal storage unit of the terminal device 13, such as a hard disk or a memory of the terminal device 13 in some embodiments. The memory 131 can also be an external storage device of the terminal device 13, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, or the like, in other embodiments. Further, the memory 131 can include both an internal storage unit and an external storage device of the terminal device 13. The memory 131 is used to store an operating system, an application program, a boot loader, data, and other programs, such as program codes of the computer program, and the like. The memory 131 can also be used to temporarily store data that has been output or will be output.

[0148] The embodiments of the present application further provide a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the steps in the above-mentioned various method embodiments.

[0149] The embodiments of the present application provide a computer program product. When the computer program product is run on a terminal device, the terminal device executes the steps in the above-mentioned various method embodiments.

[0150] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the present application can implement all or part of the processes in the above-mentioned embodiment methods through a computer program to instruct relevant hardware to complete, and the computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of each method embodiment described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms. The computer readable medium at least includes any entity or device capable of carrying the computer program code to the device / terminal equipment, recording medium, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium. For example, U disk, mobile hard disk, magnetic disk or optical disk, etc. In some jurisdictions, according to legislation and patent practice, the computer readable medium can not be an electrical carrier signal and a telecommunication signal.

[0151] In the above embodiments, the description of each embodiment has its own focus, and the parts not described or recorded in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0152] Those of ordinary skill in the art can understand that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0153] In the embodiments provided by the present application, it should be understood that the disclosed apparatus / terminal equipment and method can be implemented in other ways. For example, the above-described apparatus / terminal equipment embodiments are only schematic. For example, the division of the modules or units is only a logical function division, and there can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection between each displayed or discussed unit can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0154] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may also be distributed to multiple network units. Part or all of the units can be selected to achieve the purpose of the embodiment scheme according to actual needs.

[0155] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A filtering method of a laser radar, characterized by, The application is applied to a laser radar which receives echo signals reflected by a probe and forms point cloud data, the point cloud data includes a plurality of reflection points arranged in a scanning order, and a filtering method of the laser radar includes: For the i-th reflection point, if the (i-1)-th reflection point is a normal point, it is determined whether the i-th reflection point and the near neighbor points before the i-th reflection point have the same trend, wherein the near neighbor points before the i-th reflection point include m reflection points before the i-th reflection point in the scanning order, and m is a positive integer; If the i-th reflection point and the near neighbor points before the i-th reflection point have different trends, it is determined whether the i-th reflection point is a radiation point, wherein an angle formed by the radiation point, a neighboring point of the radiation point and an original point exceeds a preset range, and the original point represents a position of the laser radar; If the i-th reflection point is a radiation point, it is determined that the i-th reflection point is a tailing point, and the tailing point is filtered out; The method further includes: For the i-th reflection point, if the (i-1)-th reflection point is a tailing point, and the i-th reflection point is a radiation point, it is determined that the i-th reflection point is a tailing point; If the (i-1)-th reflection point is a tailing point, and the i-th reflection point is a normal point, it is determined whether the i-th reflection point and the near neighbor points before the i-th reflection point have the same trend; If the i-th reflection point and the near neighbor points before the i-th reflection point have the same trend, the (i-1)-th reflection point is corrected to be a normal point.

2. The filtering method of a lidar according to claim 1, wherein, The determination of whether the i-th reflection point and the near neighbor points before the i-th reflection point have the same trend includes: A first index value is determined according to a first distance between the i-th reflection point and the original point, and a second distance between an (i-2)-th reflection point and the original point; A third distance between an intermediate point and the original point is obtained from a first preset table according to the first index value, the intermediate point being a midpoint of a line connecting the i-th reflection point and the (i-2)-th reflection point; If a fourth distance between the (i-1)-th reflection point and the original point is within a preset range of the third distance, it is determined that the i-th reflection point and the near neighbor points before the i-th reflection point have the same trend; If the fourth distance between the (i-1)-th reflection point and the original point is not within the preset range of the third distance, it is determined that the i-th reflection point and the near neighbor points before the i-th reflection point have different trends.

3. The filtering method of a lidar according to claim 1, wherein, The determination of whether the i-th reflection point is a radiation point includes: A field angle of a line connecting the i-th reflection point and the original point, and a line connecting the original point and the (i-1)-th reflection point is calculated; A length boundary value corresponding to the field angle is searched in a second preset table; A length range is calculated according to a distance between the (i-1)-th reflection point and the original point, and the length boundary value; If a distance between the i-th reflection point and the original point is not within the length range, it is determined that the i-th reflection point is a radiation point; If the distance between the i-th reflection point and the original point is within the length range, it is determined that the i-th reflection point is a non-radiation point.

4. The filtering method of a lidar according to claim 1, wherein, Before judging whether the i-th reflection point and the adjacent point before the i-th reflection point have the same trend, the method further comprises: If the i-1-th reflection point is a normal point, judging whether the i-2-th reflection point is a trailing point; If the i-2-th reflection point is a trailing point, detecting whether the i-1-th reflection point and the adjacent point before the i-1-th reflection point have the same trend; If the i-1-th reflection point and the adjacent point before the i-1-th reflection point have the same trend, modifying the i-2-th reflection point as a normal point.

5. The filtering method of a lidar according to claim 4, wherein, The detection of whether the i-1-th reflection point and the adjacent point before the i-1-th reflection point have the same trend comprises: If the i-3-th reflection point, the i-2-th reflection point and the i-1-th reflection point have the same trend, and the i-2-th reflection point, the i-1-th reflection point and the i-th reflection point have the same trend, it is judged that the i-1-th reflection point and the adjacent point before the i-1-th reflection point have the same trend.

6. The filtering method of a lidar according to claim 1, wherein, The method further comprises: According to the scanning order, the plurality of reflection points in the point cloud data are traversed to obtain respective first marks of the plurality of reflection points, the first marks being used to represent that the reflection points are normal points or trailing points; According to the reverse order of the scanning order, the plurality of reflection points in the point cloud data are traversed to obtain respective second marks of the plurality of reflection points, the second marks being used to represent that the reflection points are normal points or trailing points; For each reflection point, if the first mark and the second mark of the reflection point both represent trailing points, it is judged that the reflection point is a trailing point; If any one of the first mark and the second mark of the reflection point represents a normal point, it is judged that the reflection point is a normal point.

7. The method of filtering for a lidar according to claim 1, wherein, After judging whether the i-th reflection point and the adjacent point before the i-th reflection point have the same trend, the method further comprises: If the i-th reflection point and the adjacent point before the i-th reflection point have the same trend, it is judged that the i-th reflection point is a normal point; After judging whether the i-th reflection point is a radiation point, the method further comprises: If the i-th reflection point is a non-radiation point, it is judged that the i-th reflection point is a normal point.

8. A filtering device of a lidar, characterized by, The filter device is applied to a laser radar, the laser radar receives echo signals reflected by a detection object and forms point cloud data, the point cloud data comprises a plurality of reflection points arranged according to a scanning order, and the filter device of the laser radar comprises: A first judging unit is configured to, for an i-th reflection point, if an i-1-th reflection point is a normal point, judge whether the i-th reflection point and an adjacent point before the i-th reflection point have the same trend, wherein the adjacent point before the i-th reflection point comprises m reflection points before the i-th reflection point in the scanning order, and m is a positive integer; A second judging unit is configured to, if the i-th reflection point and the adjacent point before the i-th reflection point have different trends, judge whether the i-th reflection point is a radiation point, wherein an angle formed by the radiation point, a neighboring point of the radiation point and an original point exceeds a preset range, and the original point represents a position of the laser radar. A result unit is configured to determine that the i-th reflection point is a trailing point if the i-th reflection point is a radiation point, and filter out the trailing point. The first determining unit is further configured to: For the i-th reflection point, if the (i-1)-th reflection point is a trailing point and the i-th reflection point is a radiation point, the i-th reflection point is determined to be a trailing point. If the (i-1)-th reflection point is a trailing point and the i-th reflection point is a normal point, it is determined whether the i-th reflection point has the same trend as the adjacent point before the i-th reflection point. If the i-th reflection point has the same trend as the adjacent point before the i-th reflection point, the (i-1)-th reflection point is corrected to be a normal point.

9. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the method in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 9. The computer program is executed by the processor to implement the method in any one of claims 1 to 7.

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