CN112136018A

CN112136018A - Point cloud noise filtering method of distance measuring device, distance measuring device and mobile platform

Info

Publication number: CN112136018A
Application number: CN201980009042.2A
Authority: CN
Inventors: 王闯; 吴特思; 陈涵; 洪小平
Original assignee: SZ DJI Technology Co Ltd
Current assignee: SZ DJI Technology Co Ltd
Priority date: 2019-04-24
Filing date: 2019-04-24
Publication date: 2020-12-25
Also published as: WO2020215252A1

Abstract

The invention provides a method for filtering noise of a point cloud of a distance measuring device, the distance measuring device and a mobile platform, wherein the method comprises the following steps: acquiring a depth value of a current point cloud point acquired by the ranging device and a depth value of at least one adjacent point cloud point adjacent to the current point cloud point (S501); inputting the depth value of the current point cloud point and the depth value of the at least one neighboring point cloud point to a predetermined filtering model to determine whether the current point cloud point is noise (S502). The method has the advantages of small required calculation amount, no time delay of a processing result, capability of filtering the cloud point of the current point in real time, high accuracy, capability of filtering various noise points including waveform fusion noise points and remarkable improvement on the point cloud quality of the distance measuring device.

Description

Point cloud noise filtering method of distance measuring device, distance measuring device and mobile platform

Description

Technical Field

The invention relates to the technical field of distance measuring devices, in particular to a method for filtering noise of a point cloud of a distance measuring device, the distance measuring device and a mobile platform.

Background

For example, the core function of a distance measuring device of a scanning laser distance measuring system is to measure distance by emitting and receiving laser, but if the laser echo entering the system is reflected by a plurality of objects close to each other, the analog signal generated after passing through a photoelectric converter is distorted due to waveform fusion, and at the moment, the depth calculated by a conventional algorithm has errors, so that noise is generated. Such noise has been long in the industry and has a large impact on the performance of the system.

Therefore, in view of the above problems, the present invention provides a method for filtering noise of a point cloud of a ranging device.

Disclosure of Invention

The present invention has been made to solve at least one of the above problems. Specifically, the invention provides a method for filtering noise of a point cloud of a ranging device, which comprises the following steps:

acquiring the depth value of a current point cloud point acquired by the distance measuring device and the depth value of at least one adjacent point cloud point adjacent to the current point cloud point;

and inputting the depth value of the cloud point of the current point and the depth value of the cloud point of the at least one adjacent point into a preset filtering model so as to determine whether the cloud point of the current point is a noise point.

Exemplarily, inputting the depth value of the current cloud point and the depth value of the at least one neighboring cloud point into a predetermined filtering model to determine whether the current cloud point is noise, specifically including:

and judging whether the change of the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point is continuous or not based on the preset filtering model so as to determine whether the cloud point of the current point is a noise point or not.

For example, the determining, based on the predetermined filtering model, whether a change in a depth value of a current point cloud point and the at least one neighboring point cloud point is continuous to determine whether the current point cloud point is a noise point specifically includes:

acquiring a threshold data set of the difference between the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point;

determining whether the current point cloud point is noisy based on whether a difference between depth values of the current point cloud point and the at least one neighboring point cloud point is within the threshold data set.

For example, the obtaining a threshold data set of a difference between the depth values of the current point cloud point and the at least one neighboring point cloud point specifically includes:

obtaining a filtering threshold coefficient based on the emission time interval of the optical pulse sequence emitted by the distance measuring device, the scanning angular velocity of the distance measuring device and an included angle, wherein the included angle is the included angle between the advancing direction of the optical pulse sequence emitted by the distance measuring device and a reference surface;

and obtaining the threshold data set based on the filtering threshold coefficient and the depth value of the cloud point of the adjacent point before the current cloud point, wherein the threshold data set comprises a threshold value which is in direct proportion to the depth value of the cloud point of the adjacent point before the current cloud point and is in inverse proportion to the included angle.

Illustratively, if the scanning angular velocity of the distance measuring device is uniform within the angle of field, the filtering threshold coefficient is a fixed value for a predetermined included angle.

For example, if the scanning angular velocity of the distance measuring device is non-uniform within the field angle, the scanning angular velocity within the entire field angle is a two-dimensional data set related to the zenith angle and the azimuth angle of the scanning, and the filtering threshold coefficient is the two-dimensional data set for the predetermined included angle.

Illustratively, if the scanning angular velocity of the distance measuring device is non-uniform within the field angle, the scanning angular velocity within the entire field angle is a two-dimensional data set related to the zenith angle and the azimuth angle of the scanning, and the filtering threshold coefficient is obtained based on the emission time interval of the pulse signal, the maximum scanning angular velocity of the distance measuring device, and the included angle.

Illustratively, the included angle is in the range of 0-90 degrees.

For example, the threshold data set includes a threshold value of a difference between the depth values of the current cloud point and its previous neighboring cloud point, and then the difference between the depth value of the current cloud point and its previous neighboring cloud point determined as noise is greater than the threshold value.

Illustratively, the filter model comprises a filter function.

Illustratively, the method further comprises:

when the cloud point of the current point is determined to be a noise point, filtering the cloud point of the current point; alternatively, the first and second electrodes may be,

and marking the cloud point of the current point determined as the noise point.

Illustratively, the method further comprises:

and outputting the point cloud points of the non-noise points collected by the distance measuring device as an image or a video.

Illustratively, the filtering out of point cloud points is performed during the process of the ranging device acquiring point cloud points.

Illustratively, the neighboring point cloud point is a point cloud point acquired before the current point cloud point.

Illustratively, the method further comprises:

assigning the depth value and/or the reflectance value of the marked current point cloud point to a special value.

Exemplarily, the obtaining of the depth value of the cloud point at the current point acquired by the ranging device specifically includes:

emitting a sequence of light pulses;

converting the received return light reflected by the object into an electric signal and outputting the electric signal;

sampling the output electrical signal to measure the time difference between transmission and reception of the optical pulse sequence;

and receiving the time difference, and calculating the depth value of the cloud point at the current point.

Yet another aspect of the invention provides a ranging device comprising one or more processors, working collectively or individually, the processors being configured to:

Illustratively, the processor is specifically configured to:

Illustratively, the processor is more specifically configured to:

Illustratively, the processor is further configured to:

Illustratively, the included angle is in the range of 0-90 degrees.

Illustratively, the filter model comprises a filter function.

Illustratively, the processor is further configured to:

and marking the cloud point of the current point determined as the noise point.

Exemplarily, the distance measuring apparatus further comprises:

and the output device is used for outputting the point cloud points of the non-noise points acquired by the distance measuring device into an image or a video.

Illustratively, the filtering out of point cloud points is performed during the process of acquiring point cloud points by the ranging device.

Illustratively, the neighboring point cloud point is a point cloud point acquired by the ranging device before the current point cloud point.

Illustratively, the processor is further configured to:

Exemplarily, the distance measuring apparatus further comprises:

a transmitter for transmitting a sequence of light pulses;

the receiving circuit is used for converting the received return light reflected by the object into an electric signal and outputting the electric signal;

a sampling circuit for sampling the output electrical signal to measure the time difference between transmission and reception of the optical pulse train;

and the operation circuit is used for receiving the time difference and calculating the depth value of the cloud point at the current point.

Illustratively, the processor comprises a field programmable gate array.

Another aspect of the present invention provides a computer storage medium, on which a computer program is stored, which when executed by a processor implements the method for point cloud noise filtering of a distance measuring device.

Yet another aspect of the present invention provides a mobile platform, comprising:

the aforementioned distance measuring device; and

the platform body, range unit installs on the platform body.

Illustratively, the mobile platform comprises a drone, a robot, a vehicle, or a boat.

The method of the embodiment of the invention acquires the depth value of the current point cloud point acquired by the distance measuring device and the depth value of at least one adjacent point cloud point adjacent to the current point cloud point; inputting the depth value of the cloud point of the current point and the depth value of the cloud point of the at least one adjacent point into a preset filtering model to determine whether the cloud point of the current point is a noise point or not, further filtering or marking the cloud point determined as the noise point, filtering various noise points including waveform fusion noise points, remarkably reducing flying line noise points and other abnormal noise points between front and back similar objects in the cloud point, and obviously optimizing and improving the quality of the point cloud; in addition, the method of the embodiment of the invention can be realized only by less calculation amount, the processing result has no time delay and high accuracy, and the process of noise filtering is almost completed in real time along with the point cloud acquisition.

Drawings

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

FIG. 1 is a schematic diagram illustrating the generation principle of multiple echoes of a laser ranging system in an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating the principle of the generation of the waveform fusion noise of the laser ranging system according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating waveform fusion noise in an embodiment of the present invention;

FIG. 4 is a schematic diagram of waveform fusion noise in another embodiment of the present invention;

FIG. 5 is a schematic flow chart diagram illustrating a method for noise filtering of a point cloud of a range finder in one embodiment of the invention;

FIG. 6 is a diagram illustrating noise points marked after applying a method of point cloud noise filtering according to an embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating a comparison of point cloud images before and after applying a method of point cloud noise filtering according to an embodiment of the present invention;

FIG. 8 is a diagram illustrating an architecture of a ranging device according to an embodiment of the present invention;

fig. 9 shows a schematic view of a distance measuring device in an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely a subset of embodiments of the invention and not all embodiments of the invention, with the understanding that the invention is not limited to the example embodiments described herein. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention described herein without inventive step, shall fall within the scope of protection of the invention.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.

It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In order to provide a thorough understanding of the present invention, a detailed structure will be set forth in the following description in order to explain the present invention. Alternative embodiments of the invention are described in detail below, however, the invention may be practiced in other embodiments that depart from these specific details.

A ranging device, such as a laser ranging system, is a sensing system that uses laser light for scanning and distance measurement to obtain three-dimensional information in a surrounding scene. The basic principle is that laser pulses are actively transmitted to a detected object, laser echo signals are captured, and the distance of the detected object is calculated according to the time difference between the transmission and the reception of the laser; obtaining angle information of the measured object based on the known emission direction of the laser; by high-frequency transmission and reception, massive distance and angle information of the detection points can be acquired, and the information is called point cloud. Three-dimensional information of the surrounding scene can be reconstructed based on the point cloud.

The laser ranging system usually emits laser light with a certain divergence angle θ (θ is a set of parameters related to the design parameters of the laser), which means that the area of the light spot increases with the distance from the emission point. Assuming that the spot area of the laser light is Sd1 at a distance d1 from the emission point, due to the complexity of the actual environment, the spot Sd1 may fall on one object in its entirety, or may fall on one object a only in one portion and another object B at a distance d2 in another portion, as shown in fig. 1.

Because the speed of light is constant under certain circumstances, as shown in fig. 2, if the distance between d1 and d2 is relatively long, the receiving system will acquire two mutually independent laser echoes; if d1 is closer to d2, the two laser echoes will gradually merge; when the distance between d1 and d2 is less than the limit distance dmin, the two laser echoes are completely merged into a waveform on the analog signal generated by the photoelectric converter. In the algorithm for calculating the distance by the laser ranging system according to the laser flight time, unless the special waveform is accurately identified and specially processed, an error distance which is neither d1 nor d2 is probably calculated, and is called noise. Of course, there are other causes of outliers that can be generalized as noise and filtered out by the present invention.

Fig. 3 and 4 show two cloud point images with waveform fusion noise, in the cloud point image shown in fig. 3, a and B are a pillar and a wall, respectively, and the C region does not have any object, but noise is generated in the C region due to the waveform fusion phenomenon described above. In the cloud point shown in fig. 4, the arrow points to a blank area between the car and the guardrail, but due to the close distance, some noise is generated.

The current conventional schemes generally have the following methods: 1) removing noise points by using an image recognition or spatial filtering method on an upper-layer operation platform; 2) identifying and denoising the bottom layer according to the waveform characteristics; 3) no treatment is carried out; however, the above scheme 1 requires a large amount of point cloud data for operation, which not only consumes a lot of resources, but also causes a certain delay in the calculation result. The difficulty of the scheme 2 is that the waveform is very close to a normal waveform, so that the waveform can hardly be distinguished from the waveform characteristics, or a large amount of misjudgments exist; scheme 3 does not add extra computation, but in some applications, the noise may have a great influence on the object identification of the point cloud, especially on the identification of objects with close distances.

In view of the above problems, an embodiment of the present invention provides a method for filtering noise of a point cloud of a ranging apparatus, as shown in fig. 5, the method includes the following steps: step S501, obtaining a depth value of a current point cloud point collected by the distance measuring device and a depth value of at least one adjacent point cloud point adjacent to the current point cloud point; step S502, inputting the depth value of the cloud point of the current point and the depth value of the cloud point of the at least one neighboring point into a predetermined filtering model to determine whether the cloud point of the current point is a noise point. The method has the advantages of small required calculation amount, no time delay of a processing result, capability of filtering the cloud point of the current point in real time, high accuracy, capability of filtering various noise points including waveform fusion noise points and remarkable improvement on the point cloud quality of the distance measuring device.

The method for filtering noise of point cloud of the ranging device of the present application is explained in detail below with reference to the accompanying drawings. The features of the following examples and embodiments may be combined with each other without conflict.

First, as shown in fig. 5, in step S501, a depth value of a current point cloud point acquired by the distance measuring device and a depth value of at least one adjacent point cloud point adjacent to the current point cloud point are acquired.

In one example, the obtaining the depth value of the cloud point at the current point acquired by the ranging apparatus specifically includes: emitting a sequence of light pulses; converting the received return light reflected by the object into an electric signal and outputting the electric signal; sampling the output electrical signal to measure the time difference between transmission and reception of the optical pulse sequence; and receiving the time difference, and calculating the depth value of the cloud point at the current point. The depth values of all the point cloud points collected by the distance measuring device can be obtained by the method.

The adjacent cloud point adjacent to the current cloud point is the cloud point acquired by the distance measuring device in a specific time period before or after the current time when the distance measuring device acquires the current cloud point.

Optionally, the adjacent point cloud point is a point cloud point acquired by the distance measuring device before the current point cloud point. Whether the cloud point of the current point is a noise point or not can be filtered in real time based on the cloud points of the adjacent points.

Next, in step S502, the depth value of the current cloud point and the depth value of the at least one neighboring cloud point are input to a predetermined filtering model to determine whether the current cloud point is noise.

In one example, inputting the depth value of the current cloud point and the depth value of the at least one neighboring cloud point to a predetermined filtering model to determine whether the current cloud point is a noise point, specifically including: and judging whether the change of the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point is continuous or not based on the preset filtering model so as to determine whether the cloud point of the current point is a noise point or not.

For example, the method for determining whether the change of the depth values of the current cloud point and the at least one neighboring cloud point is continuous may be, for example, analyzing and determining by using a relative relationship between the depth values of a plurality of points, for example, taking four neighboring cloud points as an example, the depth values of the four neighboring cloud points are d1, d2, d3 and d4, respectively, and if the differences between the depth values of d2 and d1, d3 and d2, d4 and d3 continuously change according to a predetermined rule and are all within a threshold interval of the depth difference, the data of the cloud points are considered to be normal and are not noise. And if the depth difference fluctuation is large and is not in the depth difference threshold interval, the data is considered to be abnormal and is marked and processed. The method can be used for filtering each point cloud point in the point cloud data after the distance measuring device collects the point cloud data with a preset quantity, so that the point cloud data is filtered at the distance measuring device end, or filtering the point cloud point according to the filtering method in the embodiment of the application along with the collection of each point cloud point by the distance measuring device, the noise filtering process is almost completed along with the point cloud collection in real time, the noise filtering process can be realized only by less calculation amount, and the data delay is extremely small.

In an example, the determining, based on the predetermined filtering model, whether a change in a depth value of a current point cloud point and the at least one neighboring point cloud point is continuous to determine whether the current point cloud point is a noise point specifically includes: acquiring a threshold data set of the difference between the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point; determining whether the current point cloud point is a noise point based on whether a difference between depth values of the current point cloud point and the at least one neighboring point cloud point is within the threshold data set, wherein the current point cloud point whose difference between depth values is within the threshold data set is not a noise point, and the current point cloud point whose difference between depth values exceeds the threshold data set is a noise point, for example, the threshold data set includes a threshold value of a difference between depth values of the current point cloud point and its previous neighboring point cloud point, and then determining that a difference between a depth value of the current point cloud point and its previous neighboring point cloud point is greater than the threshold value, and comparing the difference between actual depth values based on the difference between the two actual depth values with the threshold value after acquiring the actual depth value of the current point cloud point and the actual depth value of its previous neighboring point cloud point, if the difference between actual depth values is less than or equal to the threshold value, the current cloud point is not noise, and if the difference between the actual depth values is greater than the threshold, the current cloud point is noise. The filtering is real-time filtering, can be realized by only less calculation amount, has extremely small data delay, and almost completes the noise filtering process in real time along with point cloud acquisition.

The above threshold data set may be obtained by any suitable method, and in an example, the obtaining of the threshold data set of the difference between the depth values of the current point cloud point and the at least one neighboring point cloud point specifically includes: obtaining a filtering threshold coefficient based on the emission time interval of the optical pulse sequence emitted by the distance measuring device, the scanning angular velocity of the distance measuring device and an included angle, wherein the included angle is the included angle between the advancing direction of the optical pulse sequence emitted by the distance measuring device and a reference surface; and obtaining the threshold data set based on the filtering threshold coefficient and the depth value of the cloud point of the adjacent point before the current cloud point, wherein the threshold data set comprises a threshold value which is in direct proportion to the depth value of the cloud point of the adjacent point before the current cloud point and is in inverse proportion to the included angle.

The included angle theta between the advancing direction of the light pulse sequence emitted by the distance measuring device and the reference surface can be reasonably adjusted according to the actual filtering effect, optionally, the included angle can be in the range of 0-90 degrees, further, the included angle can be in the range of 0-80 degrees, or can be in the range of 0-30 degrees, 0-40 degrees, 0-50 degrees and the like. In the embodiment of the invention, the denoising effects with different intensities can be obtained by adjusting the included angle theta. When theta approaches 90 degrees, almost all point clouds which are not normally incident are filtered out according to the scheme in the embodiment of the invention; as θ approaches 0 °, the scheme according to embodiments of the invention will hardly filter any point cloud. And adjusting theta to obtain filtering of the waveform fusion noise point or other abnormal noise points to different degrees.

In one example, if the scanning angular velocity of the ranging device is uniform over the field angle, the filtering threshold coefficient is a fixed value for the predetermined angle, and the threshold value of the difference between the depth value of each current cloud point and the depth value of the adjacent cloud point before the current cloud point may be the product of the filtering threshold coefficient and the difference between the depth values of the adjacent cloud points before the current cloud point. Because the point cloud collected by the ranging device when detecting the target scene includes a plurality of point cloud points, the current point cloud point may be any one of the plurality of point cloud points, each different current point cloud point may correspond to a threshold of a difference between different depth values, or when part of the cloud points of adjacent points before the current point cloud point have the same depth value and the filtering threshold coefficient is also a fixed value, the part of the current point cloud point may also correspond to a threshold of a difference between the same depth values.

In another example, if the scanning angular velocity of the distance measuring device is non-uniform within the field angle, the scanning angular velocity within the entire field angle is a two-dimensional data set related to the zenith and azimuth angles of the scanning, and the filtering threshold coefficient is the two-dimensional data set for the predetermined included angle. A threshold dataset is obtained based on the two-dimensional dataset, thereby filtering the point cloud.

In another example, if the scanning angular velocity of the distance measuring device is non-uniform within the field angle, the scanning angular velocity within the entire field angle is a two-dimensional data set related to the zenith angle and the azimuth angle of the scanning, the maximum scanning angular velocity of the distance measuring device is found in the two-dimensional data set, the filtering threshold coefficient is obtained based on the emission time interval of the pulse signal, the maximum scanning angular velocity of the distance measuring device, and the included angle, and the filtering threshold coefficient is applied to obtain a threshold data set, and then applied to filter the current cloud point. The method has the advantages of saving resources, calculating amount and the like, and can play a preset filtering effect on the point cloud.

In a specific example, taking the depth difference based on adjacent points as an example, assuming that there exists a sufficiently large plane a (i.e. a reference plane) in space, the distance between the plane a and a distance measuring device such as a laser distance measuring system is d, the scanning angular velocity of the laser is α, and if the scanning angular velocity of the distance measuring device is uniform within the field angle, the linear velocity of the light pulse sequence (e.g. the laser) emitted by the distance measuring device scanning on the plane a is:

v＝αd

if the emitting time interval of the adjacent optical pulse sequences designed by the distance measuring device is t, when the plane A is vertical to the advancing direction of the optical pulse sequences, the distance difference value of cloud points of adjacent points measured by the distance measuring device is approximate to:

Δd＝αdt

furthermore, if the plane a forms a predetermined angle θ with the advancing direction of the optical pulse train, the distance difference between the cloud points of the adjacent points measured by the distance measuring device is approximately:

in the above formula, α and t are fixed values related to the design of the distance measuring device, d is the actual distance (i.e. depth value) of the cloud point of the current point measured by the distance measuring device, and θ is a design parameter defined in the present invention. Clearly, Δ d' is proportional to d and inversely related to θ. At a distance d, i.e. a certain Δ d', for a predetermined angle θ, its scaling factor (i.e. the filtering threshold factor) is defined as K. If the depth values of several point cloud points are measured continuously, wherein the depth values are d1, d2, d3, d4 and d5 in sequence, the difference between the depth values of the cloud points of the front point and the back point and the threshold are shown in table 1:

table 1 difference calculation and threshold generation for neighboring points

Number of points	Depth of field	Cloud point difference of adjacent points	Threshold value
1	d1	/	/
2	d2	d2-d1	K*d1
3	d3	d3-d2	K*d2
4	d4	d4-d3	K*d3
5	d5	d5-d4	K*d4

For example, for the current cloud point with the serial number of 2, if the difference between the actually measured depth value d2 of the current cloud point with the serial number of 2 and the actually measured depth value d1 of the cloud point of the adjacent point before the current cloud point is greater than the product of the filter coefficient K and the filter coefficient d1, the current cloud point with the serial number of 2 is considered as noise, and the noise is marked and processed; otherwise, the cloud point of the current point with the sequence number of 2 is considered not to be a noise point but to be a normal point, and is directly output. And in the same way, sequentially filtering each current point cloud point collected by the distance measuring device until all noise points (also called noise) are identified. As shown in fig. 6, points in the area indicated by the arrows in fig. 6 are noise points to be filtered marked by the present invention, and other areas are normal points.

In other embodiments of the present invention, the filter model includes a filter function, such as a linear filter function, a gaussian filter function, a spatial frequency distribution filter function, and the like. And identifying noise points of abnormal fluctuation by using a filter function meeting a preset condition as a judgment condition.

For the current point cloud point determined as a noise point by the above method, the current point cloud point may be processed according to a method, for example, when the current point cloud point is determined as a noise point, the current point cloud point is filtered, for example, the depth value of the current point cloud point determined as a noise point is set to 0, that is, direct filtering is performed, and optionally, the point cloud point filtering is performed during the process of the distance measuring device collecting the point cloud points, so that the distance measuring device may directly output point cloud data almost without a noise point. In another example, the current cloud point determined as a noise point is marked, a depth value and/or a reflectivity value of the marked current cloud point is assigned to a special value or the current cloud point is directly filtered, the special value is different from the depth value or the reflectivity of other cloud points without noise points, and then a processing mode is determined by an upper algorithm (i.e., an upper application), for example, an object segmentation recognition algorithm, a three-dimensional reconstruction algorithm, and the like. It should be noted that, in the embodiment of the present invention, the value after processing is used only when data is sent to the upper layer application, and the original data before filtering is always reserved in the embodiment of the present invention as a reference for the next filtering algorithm.

As shown in fig. 7, by comparing the previous and subsequent effects of the method in the embodiment of the present invention applied in the same scene, the method in the embodiment significantly reduces "flying line" noise and other abnormal noise between the previous and subsequent similar objects in the point cloud, and significantly optimizes and improves the quality of the point cloud.

In summary, the method of the embodiment of the present invention obtains the depth value of the current point cloud point acquired by the distance measuring device, and the depth value of at least one adjacent point cloud point adjacent to the current point cloud point; inputting the depth value of the cloud point of the current point and the depth value of the cloud point of the at least one adjacent point into a preset filtering model to determine whether the cloud point of the current point is a noise point or not, further filtering or marking the cloud point determined as the noise point, filtering various noise points including waveform fusion noise points, remarkably reducing flying line noise points and other abnormal noise points between front and back similar objects in the cloud point, and obviously optimizing and improving the quality of the point cloud; in addition, the method of the embodiment of the invention can be realized only by less calculation amount, the processing result has no time delay and high accuracy, and the process of noise filtering is almost completed in real time along with the point cloud acquisition.

In the following, the structure of a distance measuring device in the embodiments of the present invention is described in more detail with reference to fig. 8 and 9, the distance measuring device includes a laser radar, the distance measuring device is only used as an example, and other suitable distance measuring devices can be applied to the present application. The distance measuring device is used for executing the method for filtering the noise of the point cloud in the embodiment.

The scheme provided by each embodiment of the invention can be applied to a distance measuring device, and the distance measuring device can be electronic equipment such as a laser radar, laser distance measuring equipment and the like. In one embodiment, the ranging device is used to sense external environmental information, such as distance information, orientation information, reflected intensity information, velocity information, etc. of environmental targets. In one implementation, the ranging device may detect the distance of the probe to the ranging device by measuring the Time of Flight (TOF), which is the Time-of-Flight Time, of light traveling between the ranging device and the probe. Alternatively, the distance measuring device may detect the distance from the probe to the distance measuring device by other techniques, such as a distance measuring method based on phase shift (phase shift) measurement or a distance measuring method based on frequency shift (frequency shift) measurement, which is not limited herein.

For ease of understanding, the following describes an example of the ranging operation with reference to the ranging apparatus 100 shown in fig. 8.

Illustratively, the distance measuring device may include a transmitting module, a receiving module and a temperature control system, wherein the transmitting module is used for emitting light pulses; the receiving module is used for receiving at least part of the light pulse reflected back by the object and determining the distance of the object relative to the distance measuring device according to the received at least part of the light pulse.

Specifically, as shown in fig. 8, the transmitting module includes a transmitting circuit 110; the receiving module includes a receiving circuit 120, a sampling circuit 130, and an arithmetic circuit 140.

The transmit circuit 110 may emit a train of light pulses (e.g., a train of laser pulses). The receiving circuit 120 may receive the optical pulse train reflected by the detected object, perform photoelectric conversion on the optical pulse train to obtain an electrical signal, process the electrical signal, and output the electrical signal to the sampling circuit 130. The sampling circuit 130 may sample the electrical signal to obtain a sampling result. The arithmetic circuit 140 may determine the distance between the distance measuring device 100 and the detected object based on the sampling result of the sampling circuit 130.

Optionally, the distance measuring apparatus 100 may further include a control circuit 150, and the control circuit 150 may implement control of other circuits, for example, may control an operating time of each circuit and/or perform parameter setting on each circuit, and the like.

It should be understood that, although the distance measuring device shown in fig. 8 includes a transmitting circuit, a receiving circuit, a sampling circuit and an arithmetic circuit for emitting one light beam for detection, the embodiments of the present application are not limited thereto, and the number of any one of the transmitting circuit, the receiving circuit, the sampling circuit and the arithmetic circuit may be at least two, and the at least two light beams are emitted in the same direction or in different directions respectively; the at least two light paths may be emitted simultaneously or at different times. In one example, the light emitting chips in the at least two transmitting circuits are packaged in the same module. For example, each transmitting circuit comprises a laser emitting chip, and die of the laser emitting chips in the at least two transmitting circuits are packaged together and accommodated in the same packaging space.

In some implementations, in addition to the circuit shown in fig. 8, the distance measuring apparatus 100 may further include a scanning module for emitting at least one light pulse sequence (e.g., a laser pulse sequence) emitted from the emitting circuit with a changed propagation direction so as to scan the field of view. Illustratively, the scan area of the scan module within the field of view of the ranging device increases over time.

Here, a module including the transmission circuit 110, the reception circuit 120, the sampling circuit 130, and the operation circuit 140, or a module including the transmission circuit 110, the reception circuit 120, the sampling circuit 130, the operation circuit 140, and the control circuit 150 may be referred to as a ranging module, which may be independent of other modules, for example, a scanning module.

The distance measuring device can adopt a coaxial light path, namely the light beam emitted by the distance measuring device and the reflected light beam share at least part of the light path in the distance measuring device. For example, at least one path of laser pulse sequence emitted by the emitting circuit is emitted by the scanning module after the propagation direction is changed, and the laser pulse sequence reflected by the detector is emitted to the receiving circuit after passing through the scanning module. Alternatively, the distance measuring device may also adopt an off-axis optical path, that is, the light beam emitted by the distance measuring device and the reflected light beam are transmitted along different optical paths in the distance measuring device. FIG. 9 shows a schematic diagram of one embodiment of the ranging device of the present invention using coaxial optical paths.

The ranging apparatus 200 comprises a ranging module 210, the ranging module 210 comprising an emitter 203 (which may comprise the transmitting circuitry described above), a collimating element 204, a detector 205 (which may comprise the receiving circuitry, sampling circuitry and arithmetic circuitry described above) and a path-altering element 206. The distance measuring module 210 is configured to emit a light beam, receive return light, and convert the return light into an electrical signal. Wherein the emitter 203 may be configured to emit a sequence of light pulses. In one embodiment, the transmitter 203 may emit a sequence of laser pulses. Optionally, the laser beam emitted by the emitter 203 is a narrow bandwidth beam having a wavelength outside the visible range. The collimating element 204 is disposed on an emitting light path of the emitter, and is configured to collimate the light beam emitted from the emitter 203, and collimate the light beam emitted from the emitter 203 into parallel light to be emitted to the scanning module. The collimating element is also for converging at least a portion of the return light reflected by the detector. The collimating element 204 may be a collimating lens or other element capable of collimating a light beam.

In the embodiment shown in fig. 9, the transmit and receive optical paths within the distance measuring device are combined by the optical path changing element 206 before the collimating element 204, so that the transmit and receive optical paths can share the same collimating element, making the optical path more compact. In other implementations, the emitter 203 and the detector 205 may use respective collimating elements, and the optical path changing element 206 may be disposed in the optical path after the collimating elements.

In the embodiment shown in fig. 9, since the beam aperture of the light beam emitted from the emitter 203 is small and the beam aperture of the return light received by the distance measuring device is large, the optical path changing element can adopt a small-area mirror to combine the emission optical path and the reception optical path. In other implementations, the optical path changing element may also be a mirror with a through hole, wherein the through hole is used for transmitting the outgoing light from the emitter 203, and the mirror is used for reflecting the return light to the detector 205. Therefore, the shielding of the bracket of the small reflector to the return light can be reduced in the case of adopting the small reflector.

In the embodiment shown in fig. 9, the optical path altering element is offset from the optical axis of the collimating element 204. In other implementations, the optical path altering element may also be located on the optical axis of the collimating element 204.

The ranging device 200 also includes a scanning module 202. The scanning module 202 is disposed on the emitting light path of the distance measuring module 210, and the scanning module 202 is configured to change the transmission direction of the collimated light beam 219 emitted by the collimating element 204, project the collimated light beam to the external environment, and project the return light beam to the collimating element 204. The return light is converged by the collimating element 204 onto the detector 205.

In one embodiment, the scanning module 202 may include at least one optical element for changing the propagation path of the light beam, wherein the optical element may change the propagation path of the light beam by reflecting, refracting, diffracting, etc. the optical element includes at least one light refracting element having non-parallel exit and entrance faces, for example. For example, the scanning module 202 includes a lens, mirror, prism, galvanometer, grating, liquid crystal, Optical Phased Array (Optical Phased Array), or any combination thereof. In one example, at least a portion of the optical element is moved, for example, by a driving module, and the moved optical element can reflect, refract, or diffract the light beam to different directions at different times. In some embodiments, multiple optical elements of the scanning module 202 may rotate or oscillate about a common axis 209, with each rotating or oscillating optical element serving to constantly change the direction of propagation of an incident beam. In one embodiment, the multiple optical elements of the scanning module 202 may rotate at different rotational speeds or oscillate at different speeds. In another embodiment, at least some of the optical elements of the scanning module 202 may rotate at substantially the same rotational speed. In some embodiments, the multiple optical elements of the scanning module may also be rotated about different axes. In some embodiments, the multiple optical elements of the scanning module may also rotate in the same direction, or in different directions; or in the same direction, or in different directions, without limitation.

In one embodiment, the scanning module 202 includes a first optical element 214 and a driver 216 coupled to the first optical element 214, the driver 216 configured to drive the first optical element 214 to rotate about the rotation axis 209, such that the first optical element 214 redirects the collimated light beam 219. The first optical element 214 projects the collimated beam 219 into different directions. In one embodiment, the angle between the direction of the collimated beam 219 after it is altered by the first optical element and the axis of rotation 209 changes as the first optical element 214 is rotated. In one embodiment, the first optical element 214 includes a pair of opposing non-parallel surfaces through which the collimated light beam 219 passes. In one embodiment, the first optical element 214 includes a prism having a thickness that varies along at least one radial direction. In one embodiment, the first optical element 214 comprises a wedge angle prism that refracts the collimated beam 219.

In one embodiment, the scanning module 202 further comprises a second optical element 215, the second optical element 215 rotating around a rotation axis 209, the rotation speed of the second optical element 215 being different from the rotation speed of the first optical element 214. The second optical element 215 is used to change the direction of the light beam projected by the first optical element 214. In one embodiment, the second optical element 215 is coupled to another driver 217, and the driver 217 drives the second optical element 215 to rotate. The first optical element 214 and the second optical element 215 may be driven by the same or different drivers, such that the first optical element 214 and the second optical element 215 rotate at different speeds and/or turns, thereby projecting the collimated light beam 219 into different directions in the ambient space, which may scan a larger spatial range. In one embodiment, the controller 218 controls the

drivers

216 and 217 to drive the first optical element 214 and the second optical element 215, respectively. The rotation speed of the first optical element 214 and the second optical element 215 can be determined according to the region and the pattern expected to be scanned in the actual application. The

drives

216 and 217 may include motors or other drives.

In one embodiment, second optical element 215 includes a pair of opposing non-parallel surfaces through which the light beam passes. In one embodiment, second optical element 215 includes a prism having a thickness that varies along at least one radial direction. In one embodiment, second optical element 215 comprises a wedge angle prism.

In one embodiment, the scan module 202 further comprises a third optical element (not shown) and a driver for driving the third optical element to move. Optionally, the third optical element comprises a pair of opposed non-parallel surfaces through which the light beam passes. In one embodiment, the third optical element comprises a prism having a thickness that varies along at least one radial direction. In one embodiment, the third optical element comprises a wedge angle prism. At least two of the first, second and third optical elements rotate at different rotational speeds and/or rotational directions.

In one embodiment, the scanning module comprises 2 or 3 photorefractive elements arranged in sequence on an outgoing light path of the optical pulse sequence. Optionally, at least 2 of the photorefractive elements in the scanning module rotate during scanning to change the direction of the sequence of light pulses.

The scanning module has different scanning paths at least partially different times, and the rotation of each optical element in the scanning module 202 may project light in different directions, such as the direction of the projected light 211 and the direction 213, so as to scan the space around the distance measuring device 200. When the light 211 projected by the scanning module 202 hits the detection object 201, a part of the light is reflected by the detection object 201 to the distance measuring device 200 in the opposite direction to the projected light 211. The return light 212 reflected by the object 201 passes through the scanning module 202 and then enters the collimating element 204.

The detector 205 is placed on the same side of the collimating element 204 as the emitter 203, and the detector 205 is used to convert at least part of the return light passing through the collimating element 204 into an electrical signal.

In one embodiment, each optical element is coated with an antireflection coating. Optionally, the thickness of the antireflection film is equal to or close to the wavelength of the light beam emitted by the emitter 203, which can increase the intensity of the transmitted light beam.

In one embodiment, a filter layer is coated on a surface of a component in the distance measuring device, which is located on the light beam propagation path, or a filter is arranged on the light beam propagation path, and is used for transmitting at least a wave band in which the light beam emitted by the emitter is located and reflecting other wave bands, so as to reduce noise brought to the receiver by ambient light.

In some embodiments, the transmitter 203 may include a laser diode through which laser pulses in the order of nanoseconds are emitted. Further, the laser pulse reception time may be determined, for example, by detecting the rising edge time and/or the falling edge time of the electrical signal pulse. In this manner, the ranging apparatus 200 may calculate TOF using the pulse reception time information and the pulse emission time information, thereby determining the distance of the probe 201 to the ranging apparatus 200. The distance and orientation detected by ranging device 200 may be used for remote sensing, obstacle avoidance, mapping, modeling, navigation, and the like.

In some embodiments, the ranging device further comprises one or more processors, one or more memory devices, the one or more processors operating collectively or individually. Optionally, the ranging device may further include at least one of an input device (not shown), an output device (not shown), and an image sensor (not shown), which are interconnected by a bus system and/or other form of connection mechanism (not shown).

The storage means, i.e. the memory, is used for storing a memory for processor executable instructions, e.g. for corresponding steps and program instructions present in a method for implementing a ranging device point cloud noise filtering according to an embodiment of the invention. May include one or more computer program products that may include various forms of computer-readable storage media, such as volatile memory and/or non-volatile memory. The volatile memory may include, for example, Random Access Memory (RAM), cache memory (cache), and/or the like. The non-volatile memory may include, for example, Read Only Memory (ROM), hard disk, flash memory, etc.

The input device may be a device used by a user to input instructions and may include one or more of a keyboard, a mouse, a microphone, a touch screen, and the like.

The output device may output various information (e.g., images or sounds) to the outside (e.g., a user), and may include one or more of a display, a speaker, and the like, for outputting the point cloud points of non-noise points collected by the ranging device as images or videos.

A communication interface (not shown) is used for communication between the ranging apparatus and other devices, including wired or wireless communication. The ranging device may access a wireless network based on a communication standard, such as WiFi, 2G, 3G, 4G, 5G, or a combination thereof. In one exemplary embodiment, the communication interface receives a broadcast signal or broadcast associated information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, the communication interface further comprises a Near Field Communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on Radio Frequency Identification (RFID) technology, infrared data association (IrDA) technology, Ultra Wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

The processor may be a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other form of processing unit having data processing capabilities and/or instruction execution capabilities, and may control other components in the ranging apparatus to perform desired functions. The processor can execute the instructions stored in the storage device to execute the method for noise filtering of the point cloud of the ranging apparatus described herein, which is described in the foregoing embodiments and is not repeated herein. For example, a processor can include one or more embedded processors, processor cores, microprocessors, logic circuits, hardware Finite State Machines (FSMs), Digital Signal Processors (DSPs), or a combination thereof. In this embodiment, the processor comprises a Field Programmable Gate Array (FPGA), wherein the arithmetic circuitry of the ranging device may be part of the Field Programmable Gate Array (FPGA).

In one embodiment, the distance measuring device of the embodiment of the invention can be applied to a mobile platform, and the distance measuring device can be installed on a platform body of the mobile platform. The mobile platform with the distance measuring device can measure the external environment, for example, the distance between the mobile platform and an obstacle is measured for the purpose of avoiding the obstacle, and the external environment is mapped in two dimensions or three dimensions. In certain embodiments, the mobile platform comprises at least one of an unmanned aerial vehicle, an automobile, a remote control car, a robot, a boat, a camera. When the distance measuring device is applied to the unmanned aerial vehicle, the platform body is a fuselage of the unmanned aerial vehicle. When the distance measuring device is applied to an automobile, the platform body is the automobile body of the automobile. The vehicle may be an autonomous vehicle or a semi-autonomous vehicle, without limitation. When the distance measuring device is applied to the remote control car, the platform body is the car body of the remote control car. When the distance measuring device is applied to a robot, the platform body is the robot. When the distance measuring device is applied to a camera, the platform body is the camera itself.

The distance measuring device in the embodiment of the invention is used for executing the method, and the mobile platform comprises the distance measuring device, so that the distance measuring device and the mobile platform have the same advantages as the method.

In addition, the embodiment of the invention also provides a computer storage medium, and the computer storage medium is stored with the computer program. One or more computer program instructions may be stored on the computer-readable storage medium, and a processor may execute the program instructions stored by the storage device to implement the functions (implemented by the processor) of the embodiments of the present invention described herein and/or other desired functions, for example, to execute the corresponding steps of the method for noise filtering of a point cloud of a ranging apparatus according to the embodiments of the present invention, and various applications and various data, such as various data used and/or generated by the applications, may also be stored in the computer-readable storage medium.

For example, the computer storage medium may include, for example, a memory card of a smart phone, a storage component of a tablet computer, a hard disk of a personal computer, a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM), a portable compact disc read only memory (CD-ROM), a USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media. For example, one computer readable storage medium contains computer readable program code for converting point cloud data into a two-dimensional image and/or three-dimensional reconstruction of point cloud data, another computer readable storage medium contains computer readable program code for object segmentation of the two-dimensional image, and so forth.

Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the foregoing illustrative embodiments are merely exemplary and are not intended to limit the scope of the invention thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described device embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another device, or some features may be omitted, or not executed.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the invention and aiding in the understanding of one or more of the various inventive aspects. However, the method of the present invention should not be construed to reflect the intent: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

The various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functionality of some of the modules according to embodiments of the present invention. The present invention may also be embodied as apparatus programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present invention may be stored on computer-readable media or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

Claims

A method for filtering noise of a point cloud of a distance measuring device is characterized by comprising the following steps:

acquiring the depth value of a current point cloud point acquired by the distance measuring device and the depth value of at least one adjacent point cloud point adjacent to the current point cloud point;

and inputting the depth value of the cloud point of the current point and the depth value of the cloud point of the at least one adjacent point into a preset filtering model so as to determine whether the cloud point of the current point is a noise point.
The method of claim 1, wherein inputting the depth value of the current cloud point and the depth value of the at least one neighboring cloud point into a predetermined filter model to determine whether the current cloud point is noisy, comprises:

and judging whether the change of the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point is continuous or not based on the preset filtering model so as to determine whether the cloud point of the current point is a noise point or not.
The method according to claim 2, wherein the determining whether the change of the depth values of the current point cloud point and the at least one neighboring point cloud point is continuous based on the predetermined filtering model to determine whether the current point cloud point is noisy comprises:

acquiring a threshold data set of the difference between the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point;

determining whether the current point cloud point is noisy based on whether a difference between depth values of the current point cloud point and the at least one neighboring point cloud point is within the threshold data set.
The method of claim 3, wherein the obtaining the threshold data set of the difference between the depth values of the current point cloud point and the at least one neighboring point cloud point comprises:

obtaining a filtering threshold coefficient based on the emission time interval of the optical pulse sequence emitted by the distance measuring device, the scanning angular velocity of the distance measuring device and an included angle, wherein the included angle is the included angle between the advancing direction of the optical pulse sequence emitted by the distance measuring device and a reference surface;

and obtaining the threshold data set based on the filtering threshold coefficient and the depth value of the cloud point of the adjacent point before the current cloud point, wherein the threshold data set comprises a threshold value which is in direct proportion to the depth value of the cloud point of the adjacent point before the current cloud point and is in inverse proportion to the included angle.
The method of claim 4, wherein the filter threshold coefficient is a fixed value for a predetermined angle of view if the scanning angular velocity of the ranging device is uniform over the angle of view.
The method of claim 4, wherein if the scanning angular velocity of the ranging device is non-uniform over the field angle, the scanning angular velocity over the field angle is a two-dimensional data set related to the zenith and azimuth angles of the scan, and the filter threshold coefficient is the two-dimensional data set for a predetermined said included angle.
The method of claim 4, wherein if the scanning angular velocity of the ranging device is non-uniform over the field angle, the scanning angular velocity over the field angle is a two-dimensional data set related to the zenith and azimuth angles of the scan, and the filtering threshold coefficient is obtained based on the emission time interval of the pulse signal, the maximum scanning angular velocity of the ranging device, and the included angle.
The method of claim 4, wherein the included angle is in the range of 0 ° to 90 °.
The method of claim 3, wherein the threshold data set comprises a threshold of a difference between depth values of the current point cloud point and its previous neighboring point cloud point, and wherein the difference between the depth value of the current point cloud point and its previous neighboring point cloud point determined to be noise is greater than the threshold.
The method of claim 1, wherein the filter model comprises a filter function.
The method of any one of claims 1 to 10, further comprising:

when the cloud point of the current point is determined to be a noise point, filtering the cloud point of the current point; alternatively, the first and second electrodes may be,

and marking the cloud point of the current point determined as the noise point.
The method of any one of claims 1 to 10, further comprising:

and outputting the point cloud points of the non-noise points collected by the distance measuring device as an image or a video.
The method of claim 11,

the filtering out of the point cloud points is performed in the process of collecting the point cloud points by the distance measuring device.
The method of claim 1, wherein the neighboring point cloud point is a point cloud point acquired before the current point cloud point.
The method of claim 11, wherein the method further comprises:

assigning the depth value and/or the reflectance value of the marked current point cloud point to a special value.
The method according to any one of claims 1 to 10, wherein the obtaining of the depth value of the current cloud point acquired by the ranging apparatus comprises:

emitting a sequence of light pulses;

converting the received return light reflected by the object into an electric signal and outputting the electric signal;

sampling the output electrical signal to measure the time difference between transmission and reception of the optical pulse sequence;

and receiving the time difference, and calculating the depth value of the cloud point at the current point.
A ranging device comprising one or more processors, working together or separately, the processors being configured to:

acquiring the depth value of a current point cloud point acquired by the distance measuring device and the depth value of at least one adjacent point cloud point adjacent to the current point cloud point;

and inputting the depth value of the cloud point of the current point and the depth value of the cloud point of the at least one adjacent point into a preset filtering model so as to determine whether the cloud point of the current point is a noise point.
The ranging apparatus of claim 17, wherein the processor is specifically configured to:

and judging whether the change of the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point is continuous or not based on the preset filtering model so as to determine whether the cloud point of the current point is a noise point or not.
A ranging apparatus as claimed in claim 18 wherein the processor is more particularly adapted to:

acquiring a threshold data set of the difference between the depth values of the cloud point of the current point and the cloud point of the at least one adjacent point;

determining whether the current point cloud point is noisy based on whether a difference between depth values of the current point cloud point and the at least one neighboring point cloud point is within the threshold data set.
The ranging apparatus of claim 19, wherein the processor is further configured to:

obtaining a filtering threshold coefficient based on the emission time interval of the optical pulse sequence emitted by the distance measuring device, the scanning angular velocity of the distance measuring device and an included angle, wherein the included angle is the included angle between the advancing direction of the optical pulse sequence emitted by the distance measuring device and a reference surface;

and obtaining the threshold data set based on the filtering threshold coefficient and the depth value of the cloud point of the adjacent point before the current cloud point, wherein the threshold data set comprises a threshold value which is in direct proportion to the depth value of the cloud point of the adjacent point before the current cloud point and is in inverse proportion to the included angle.
The range finder device of claim 20, wherein the filter threshold coefficient is a fixed value for a predetermined angle of view if a scanning angular velocity of the range finder device is uniform over the angle of view.
The range finder device of claim 20, wherein if the scanning angular velocity of said range finder device is non-uniform over the field angle, the scanning angular velocity over the field angle is a two-dimensional data set related to the zenith and azimuth angles scanned, and said filter threshold coefficient is a two-dimensional data set for a predetermined said included angle.
The ranging apparatus as claimed in claim 20, wherein if the scanning angular velocity of the ranging apparatus is non-uniform within the field angle, the scanning angular velocity within the entire field angle is a two-dimensional data set related to the zenith and azimuth angles of scanning, and the filtering threshold coefficient is obtained based on the emission time interval of the pulse signal, the maximum scanning angular velocity of the ranging apparatus, and the included angle.
A ranging apparatus as claimed in claim 20 wherein said included angle is in the range 0 to 90 °.
The ranging apparatus of claim 19, wherein the threshold data set comprises a threshold of a difference between depth values of the current cloud point and its previous neighboring cloud point, and wherein the difference between the depth value of the current cloud point and its previous neighboring cloud point determined to be noise is greater than the threshold.
The ranging apparatus of claim 17 wherein said filter model comprises a filter function.
A ranging apparatus as claimed in any of claims 17 to 26 wherein the processor is further adapted to:

when the cloud point of the current point is determined to be a noise point, filtering the cloud point of the current point; alternatively, the first and second electrodes may be,

and marking the cloud point of the current point determined as the noise point.
A ranging apparatus as claimed in any of claims 17 to 26, further comprising:

and the output device is used for outputting the point cloud points of the non-noise points acquired by the distance measuring device into an image or a video.
The range finder device of claim 27, wherein the filtering out of point cloud points is performed during acquisition of point cloud points by the range finder device.
The ranging apparatus of claim 17, wherein the neighboring point cloud point is a point cloud point acquired by the ranging apparatus prior to the current point cloud point.
The ranging apparatus of claim 27, wherein the processor is further configured to:

assigning the depth value and/or the reflectance value of the marked current point cloud point to a special value.
A ranging apparatus as claimed in any of claims 17 to 26, further comprising:

a transmitter for transmitting a sequence of light pulses;

the receiving circuit is used for converting the received return light reflected by the object into an electric signal and outputting the electric signal;

a sampling circuit for sampling the output electrical signal to measure the time difference between transmission and reception of the optical pulse train;

and the operation circuit is used for receiving the time difference and calculating the depth value of the cloud point at the current point.
A ranging apparatus as claimed in any of claims 17 to 26 wherein the processor comprises a field programmable gate array.
A computer storage medium on which a computer program is stored, which program, when executed by a processor, carries out the method of any one of claims 1 to 16.
A mobile platform, comprising:

a ranging apparatus as claimed in any of claims 17 to 33; and

the platform body, range unit installs on the platform body.
The mobile platform of claim 35, wherein the mobile platform comprises a drone, a robot, a vehicle, or a boat.