KR20150049934A - A Method for Filtering Ground Data and An Apparatus thereof - Google Patents

Abstract

Disclosed are a method for filtering ground data and an apparatus thereof. The apparatus comprises: a sensor which receives data about objects around a vehicle; a storage part which stores the received data and predetermined standards; and a processing part which compares the received data and predetermined standards, and filters the data about the objects which are judged to represent the ground among the objects around the vehicle.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method of filtering ground data,

The present invention relates to a technique for analyzing measured information using a laser emitted from a sensor of a vehicle, filtering ground data and determining data for the obstacle.

Generally, data measured using sensors such as LiDAR include information about all objects detected within the measurement range. However, depending on the purpose of the system, the data on some of the sensed data may become unnecessary as noise data. For example, in the case of a vehicle system that recognizes surrounding objects, surrounding vehicles, people, etc., data that is detected when the ground is detected is unnecessary and should be removed. In the case of multi-layer LiDAR, the lower layer often faces the ground, and if not, it may happen that the vehicle is facing the ground due to rolling or pitching of the vehicle.

The present invention aims to provide a method and apparatus for efficiently filtering ground data from data measured using a sensor.

It is to be understood, however, that the invention is not to be limited to the disclosed embodiments, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

According to an aspect of the present invention, there is provided an apparatus for filtering ground surface data, comprising: a sensor for receiving data on an object around the vehicle; A storage unit for storing the received data and a predefined criterion; And a processing unit for comparing the received data with the predefined criterion to filter data on the object that is determined to represent the ground surface of the object around the vehicle.

In addition, the sensor emits one or more beams for sensing the object, and each of the beams may include a plurality of different layers.

The processing unit may obtain a slope from the data of the objects sensed in two adjacent layers of the layer, and when the slope corresponds to the predefined criterion, determine that the sensed object represents a ground .

In addition, the processing unit may acquire a distance between the sensor and the sensed object from data of objects sensed in two layers adjacent to each other among the layers, and determine whether a difference value of the obtained distances corresponds to the predefined criterion , It can be determined that the detected object represents a ground surface.

If the EPW value included in the received data corresponds to the predefined criterion, the processing unit may indicate the ground surface of the object as an EPW value It can be judged.

In addition, the predefined criteria may include a reference angle, a reference distance difference, and a reference EPW value indicating a road, and the processing unit may calculate a slope, a slope, and a slope from the data of the objects detected in two adjacent layers, And EPW values included in the received data are compared with the reference angle, the reference distance difference, and the reference EPW value, respectively, and if it is determined in all cases that the object represents a ground surface, You can filter the data for.

Also, a method for filtering ground surface data of a vehicle system to solve the above-described problems includes receiving data on an object around a vehicle using a sensor; Storing the received data in a storage unit; Comparing the received data with a predefined criterion; And filtering the data determined as representing the ground of the object based on the comparison result.

According to the present invention, when data around the vehicle is sensed by using a sensing unit such as a lidar sensor, the effect of filtering the data corresponding to the ground effectively to provide the processing result of ensuring accuracy and reliability have.

FIG. 1 shows a general situation in which the sensor is used to detect the vicinity of a vehicle.
Fig. 2 shows an exemplary image obtained by processing information on an object in front of the vehicle.
FIG. 3 shows a method of identifying data judged as a ground surface among data sensed by a sensor.
4 shows an example of a ground data filtering apparatus according to the present invention.
Figures 5A and 5B illustrate examples of a floor data filtering system according to the present invention.
FIG. 6 shows a flowchart of a method of processing sheet data according to the present invention.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted. In other words, it should be noted that only parts necessary for understanding the operation according to the embodiment of the present invention will be described, and descriptions of other parts will be omitted so as not to disturb the gist of the present invention.

In the following description, the electronic device according to the present invention may be applied to all information communication devices, multimedia devices, and application devices supporting the functions described in the various embodiments of the present invention, such as AP (Application Processor), GPU (Graphic Processing Unit) And may include all devices using a CPU (Central Processing Unit). For example, the electronic device may include a mobile communication terminal operating based on communication protocols corresponding to various communication systems, a tablet PC (personal computer), a smart phone, A digital camera, a portable multimedia player (PMP), a telematics, a navigation device, and an in-vehicle system.

In the present specification, an object refers to a target detected by a sensor. For example, a sensor may emit one or more beams to collect information about the object from the reflected beam, wherein the subject that reflects the beam may be understood as an object herein. Objects such as ground, roads, sidewalls, and obstacles can correspond to objects.

FIG. 1 shows a general situation in which the sensor is used to detect the vicinity of a vehicle. The vehicle 100 may include a sensor 110 for collecting information such as a front obstacle on the front side. The sensor 110 may emit a laser-like beam and collect information about an object in the vicinity of the vehicle 100 from data reflected and returned. Referring to FIG. 1, a vehicle 100 is traveling on an uneven road surface 130, and an obstacle 120 such as a pedestrian is located in front of the vehicle 100. Some of the beam emitted from the sensor senses the road 130, while the other part senses the obstacle 120. The beam emitted from the sensor 110 may be radiated at a plurality of angles relative to the ground. That is, the beam emitted from the sensor 110 may have a plurality of layers in a direction perpendicular to the paper surface. In this case, if the lowest layer is parallel to the ground, or if it indicates an upward direction with respect to the ground, if it meets a certain degree of uphill road or if the road surface condition is uneven, Can be collected.

Data collected via the sensor 110 may be processed and displayed to a user (e.g., a vehicle operator). An exemplary image related to this is shown in FIG.

Fig. 2 shows an exemplary image obtained by processing information on an object in front of the vehicle. The first image 210 represents an image of the front of the vehicle photographed by the camera. The second image 220 is a processed image generated based on the data collected from the sensor. Although not shown, a second processed image that has been processed in a user-friendly manner by filtering the ground data in the second image 220 may be provided through a display unit such as a telematics of a vehicle, a head unit display (HUD), or a smart device .

Referring to the first image 210, there is no obstacle ahead of the current vehicle. However, in addition to the data judged to have been collected from the walls on both sides of the road in the processed second image 220 based on the data sensed through the sensor, the data actually sensed by the drawing is judged to be a specific obstacle ahead Data that can be stored. That is, in the second image 220, the front road surface is measured and appears as if there is an obstacle. The images ultimately provided to the user are required to filter such data. Hereinafter, referring to FIG. 3, a method of identifying data determined as a ground will be described.

FIG. 3 shows a method of identifying data judged as a ground surface among data sensed by a sensor. Although the sensor in FIG. 3 is shown to mean a Lidar sensor, any kind of sensor, for example a radar or ultrasonic sensor, to which the method disclosed herein is applicable can also be understood as a sensor shown in FIG.

In Fig. 3, it can be understood that the direction in which the vehicle travels is the y-axis, the left-right direction of the vehicle traveling direction is the x-axis, and the direction perpendicular to the ground is the z-axis. For example, if the Lidar sensor can sense a field of vision (FOV) of 100 degrees forward of the vehicle and the resolution is 0.1 °, then the FID of the Lidar sensor consists of 1,000 beams . Further, when the Raida sensor supports four layers, each beam can be composed of four layers. When the Raida sensor detects the front of the vehicle, 1,000 data for each layer, 4,000 data pieces can be detected. Of course, this is exemplary, and the FOV, resolution, and number of layers supported by the Lidar sensor can be adjusted differently according to specific embodiments. In one example, the vehicle may have a plurality of Lidar sensors, and the FOV may change due to the rotatable characteristics of the sensor. However, even in a series of modified examples, the principles described below still apply to the method of filtering the data corresponding to the ground from the data sensed by the sensor. In the following, the description will be made on the basis of a LIDAR sensor supporting FOV of 100 DEG, resolution of 0.1 DEG, and four layers.

The left image of FIG. 3 shows the object detection for the same layer based on the traveling direction (y-axis) of the vehicle. In this example, a Lidar sensor mounted on a vehicle collects information about an object to be sensed using 1000 beams in a forward reference 100 [deg.] Range. If the illustrated layer is the first (lowest located) layer, each beam can be divided into 7 beams (1,1), beams (1,2), or beams (1,1000). If it is the second layer, it can be divided into beam (2,1), beam (2,2), or beam (2,1000). That is, the beam emitted from the Raid sensor can be divided into a beam (layer, n). The information collected at this time may include the distance from the sensor to the object, the movement of the object, and the width of the received reflected signal (EPW: Echo Pulse Width).

The right image of FIG. 3 shows the detection of an object with respect to the beam of the same order, with respect to the traveling direction (y-axis) of the vehicle. For convenience, it can be understood as data for the 100th beam from the left side (the driver side with respect to the center of the vehicle). That is, the beam shown in the right image of FIG. 3 can be understood as beam (1,100), beam (2,100), beam (3,100), and beam (4,100).

Objects around the vehicle are detected by the beam emitted from the Lidar sensor. By the 100th beam, four sensed data are obtained for each layer (i.e., from the first layer to the fourth layer), one by one. The values obtained by each of the above-described beams can be defined as value (1,100), value (2,100), value (3,100), and value (4,100). For the sake of convenience, the four beams shown as B1, B2, B3, and B4 will be referred to for convenience, and four detected values will be described as V1, V2, V3, and V4.

(1) Tilt condition

If V1 and V2 are ground-sensed data by sensors and V3 and V4 are data sensed by obstacles, the hypothetical line connecting V1 and V1 is relative to the hypothetical line connecting V3 and V4 The angle (inclination) with respect to the ground becomes small. (I.e.,? 1 <? 2). Further, in general, the angle with respect to the measurement direction (traveling direction of the vehicle) of the Lidar sensor is close to 0 in the case of a ground surface and close to 90 degrees in the case of an obstacle.

The slope of this hypothetical line can be obtained using a simple trigonometric function. Generally, the radiation angle of the beam constituting the layer of the Raid sensor is fixed. For example, when the radiation angle of the first layer is?, The radiation angle of the second layer is? With respect to the z-axis, and the first layer is lower than the second layer,? 1 is expressed by the following equation Can be determined.

Where r1 is the distance from the sensor to the V1 detection point, and r2 is the distance from the sensor to the V2 detection point. The slope is not always determined by the above equation, but can be obtained based on appropriate approximation and correction.

A predetermined reference value for determining whether the sensed data corresponds to the paper surface can be set. This reference value is based on information such as the height at which the Lidar sensor is located, the angle at which the beam is emitted (at the z-axis) in each layer of the RidA sensor, and the angle at which the beam is emitted at the same layer Can be set. If the measured slope is smaller than this reference value, it can be judged as an obstacle if the measured slope is larger than this reference value. Such a reference value may be determined experimentally or may be set by a user.

A predetermined reference range for judging whether or not the sensed data corresponds to the ground can be set. For example, if the slope is less than 20 degrees, it may be judged as a road, if it is more than 20 degrees but less than 60 degrees, it may be judged as a judgment suspension, and if it is more than 60 degrees, In the illustrated example, the slope measured by the first layer and the second layer is included in the range of the road, but the slope measured by the second layer and the third layer may be included in the judgment pending range. In this case, if the slope measured by the third layer and the fourth layer is included in the obstacle range, the data measured by the third layer may ultimately be determined as an obstacle. Alternatively, the nature of the data sensed by the third layer may be finally determined by the density condition or the EPW condition described later.

(2) density condition

Even if the above-described slope is relatively large, it may correspond to a road. For example, if there is a low jaw in front, or if it is located at a high hill length in front of the vehicle, the slope of the hypothetical line connecting the measured values in the two layers can be measured to a large extent. Or a situation in which it is difficult to reliably determine whether or not the measured data is road by the inclination condition. As a way to overcome this, we can use the density of the measured values.

Generally, roads are flat and exist over a wide range, even if there is a curvature, so that the operation of the vehicle is not hindered. On the other hand, obstacles such as pedestrians, other vehicles, and roadside trees are often arranged vertically on the road. Therefore, as described above, when the beam included in the first layer and the second layer is directed to the road surface, and the beam included in the third layer and the fourth layer is directed to the obstacle, The distance r1 from the distance r1 to the object (road) to the object (road) measured from the second layer becomes relatively longer due to the characteristics of the road. That is, the distribution of distance values appears dispersedly. However, the distance (r3) to the object (obstacle) measured in the third layer and the distance (r4) to the object (obstacle) measured in the fourth layer have almost similar values. That is, the distribution of the distance value is concentrated on a specific value. Therefore, when the distances detected by the sensors at different layers appear densely within a specified reference value, the corresponding data can be determined as data detected as an obstacle. For example, if the distance value measured by beam (3,800) to beam (3,900) and beam (4,800) to beam (4,900) is detected within a specified reference value (for example, within 50 cm) It can be judged that there is a predetermined obstacle on the right side of the traveling direction.

(3) EPW condition

The echo pulse width can be used to determine whether the sensed data represents the ground or an obstacle. Generally, in the case of the ground, the incidence angle of the beam is large, and in the case of the road, the color of the asphalt is often black. Therefore, the EPW value of the beam reflected from an object generally corresponding to the ground is larger than the EPW value of the beam reflected from the obstacle.

Each beam is composed of a plurality of layers as shown in Fig. 3, and a slope can be obtained from the data of the object detected at the adjacent layer. For example, both V1 obtained at the first layer and V2 obtained at the second layer are data on the ground, from which the slope with respect to the ground can be obtained. V2 and V3 are data obtained from the ground and obstacles, respectively. The slope obtained therefrom can have an appropriate value between the slope of the normal ground and the slope of the normal obstacle. Also, both V3 and V4 are data obtained from the obstacle from which the slope of the obstacle can be obtained. In this manner, the slopes between the objects detected in the adjacent two layers can be obtained by comparing sequentially from the first layer to the fourth layer or from the lower layer to the upper layer.

 In a similar manner, a distance difference between objects measured at adjacent layers can be obtained. The distances between the objects corresponding to V1, V2, V3 and V4 can be obtained as r1, r2, r3 and r4 and the distance difference values of r1 and r2, r2 and r3, r3 and r4 can be obtained have. In the illustrated example, the distance difference value between r1 and r2, r2 and r3 has a relatively large value, but the distance difference value between r3 and r4 corresponding to the obstacle has a relatively small value. That is, the distribution of the distance values becomes dense.

When at least one of the slope condition, the dense condition, and the EPW condition is satisfied, the object can be determined as data obtained from the ground. However, in one embodiment, in order to improve the accuracy of the filtering result, an object satisfying all three conditions can be determined to represent the ground surface.

Hereinafter, a ground data filtering apparatus according to an embodiment of the present invention will be described with reference to FIGS.

4 shows an example of a ground data filtering apparatus according to the present invention. 4, the ground data filtering apparatus 400 includes a sensing unit 410, a storing unit 420, a processing unit 430, and a display unit (not shown) 440). The storage 420 may also include a data matrix 422, an EPW value 424, and other predefined reference values.

The sensing unit 410 may be a sensor. For example, a radar sensor, a radar sensor, an ultrasonic sensor, or the like may correspond to the sensing unit 410. The sensing unit 410 receives data about an object located in the vicinity of the vehicle. In addition, the sensing unit 410 may include two or more sensors, and the position at which the sensor is attached to the vehicle may be fixed, fluid, or may be adjusted by a user.

The range sensed by the sensing unit 410 may correspond to the full azimuth of the vehicle depending on the attachment position of the sensor. The present invention can be generally understood as a predetermined range in front of the vehicle. The predetermined range is determined by the characteristics of the sensor. For example, when the FOV of the sensor is 100 °, the predetermined range is a linear distance supported by the beam characteristics of the sensor within a range of 50 ° to the left and right from the position where the sensor is located on the vehicle, It can be an area of the form. For example, if the beam of the sensor can measure up to the linear distance L, and the FOV is?, The predetermined range is 0.5 *? * L ² . In addition, the sensor can sense an object from a region extending over a plurality of layers corresponding to the predetermined range according to a layer supported by the sensor.

The storage unit 420 stores data about objects collected by the sensor. The storage unit may be an HDD, an SSD, an SD card, or a flash memory. The data may be stored in a sort of data matrix 422. The data matrix 422 may be composed of a layer row and a beam column. For example, the first row includes data about objects collected in the first layer, and the second row includes data about objects collected from the second layer. Such a data matrix sequentially compares data corresponding to a corresponding layer row in the same beam column (for example, comparing the values of the first layer, the second layer, ..., the nth layer with respect to the first beam ) To determine whether the object is an object representing a ground surface.

The storage 420 may also store EPW values 424. In addition, the EPW values indicating that the road is generally stored may be stored in the storage unit 420 in advance. Such EPW values 242 may be used to determine whether the data received from the object is road or not. In addition, the storage unit 420 may include information on a value of a reference angle used to determine whether the object represents a ground, a value of a reference distance difference, or a range thereof (for example, Other data 426)

The processing unit 430 may determine whether the object represents a ground using the data stored in the storage unit 420. For example, the processing unit 430 may calculate, from data on objects detected in two adjacent layers (i.e., adjacent two rows) in the data matrix, an angle formed by an imaginary solid line connecting the two objects with the ground, Can be obtained. This obtained slope is compared with a predefined criterion. If the obtained inclination is smaller than the predetermined angle or included in the range of the angle defined as representing the ground, that is, if the inclination condition is satisfied, it can be determined that the object represents the ground.

In addition, the processing unit 430 can obtain the distance between the sensor and the object from the data of the object sensed in two adjacent layers. If the difference between the distance values between the two objects and the sensor is less than a predetermined size or included in a range of sizes defined as representing the ground, that is, if the density condition is satisfied, the object may be determined to represent the ground have.

In addition, when the EPW value included in the received data is the EPW value corresponding to the road, the processing unit 430 can determine that the object represents the ground surface.

Data on an object satisfying at least one of the above criteria can be judged as ground data, but it is also possible to judge data on an object satisfying all of the above-mentioned criteria as ground data in order to improve the accuracy.

The display unit 440 provides the user or the vehicle driver with the filtered result of the ground surface data. At this time, the provided image may be a user-friendly and properly processed image. For example, if the ground data indicates that the filtered detection result has an obstacle within a certain forward distance, steering guidance of the steering wheel may be provided together with guidance of the position or distance.

Such a display or other part of the device 400 may be implemented as a separate stand-alone device, an example of which will be described with reference to FIGS. 5A and 5B.

Figures 5A and 5B illustrate examples of a floor data filtering system according to the present invention. In explaining the configurations shown in Figs. 5A and 5B, the description overlapping with the above-described configuration will be omitted.

Referring to FIG. 5A, the system includes a processing unit 510 and a display unit 520. The processing unit 520 includes the sensing unit 410, the storage unit 420, and the processing unit 430 described above, and further includes a communication unit 450. The communication unit 450 may be connected to the communication unit 524 included in the display device 520 to provide data so that the result of filtering the ground data by the display unit 522 of the display device 520 is displayed. The connection between the communication unit 450 and the communication unit 524 is possible not only by a wired connection such as a LAN but also by a local communication such as Wi-Fi, Bluetooth, or NFC. For example, the processing unit 510 may be a telematics system mounted on a vehicle, and the display device 520 may be a mobile computing device such as a smart phone, a tablet, or a smart watch capable of communicating with telematics. The display device 520 may also be the HUD of the vehicle.

5B shows another configuration example of the system. Referring to FIG. 5B, the sensing unit 410 is configured independently of the processing unit 530. The sensing unit 410 and the processing unit 530 may be connected by a CAN bus or the like. By replacing the sensing unit 410 with the processing unit 530, the sensing unit 410 can be easily replaced, replaced, or added.

FIG. 6 shows a flowchart of a method of processing sheet data according to the present invention. The process begins at step 610. In step 620, the system collects data about objects located around the vehicle using sensors and the like. The sensor emits one or more beams to sense the object, and the beam has a plurality of layers. In step 630, the system stores the data received by the sensor in the storage. The data to be stored may have the form of a data matrix. The description of the data matrix is omitted as it has been described above. The EPW value included in the received data can also be stored. In steps 642, 644, and 646, the received data, or data obtained therefrom, is compared with a predefined criterion in the system. Steps 642, 644 and 646 may be performed sequentially or concurrently.

In step 642, the slope for the two objects detected in the adjacent layer is determined. The inclination may refer to an angle formed by a virtual solid line connecting the two objects with the ground surface.

At step 644, the density of the two objects detected in the adjacent layer is determined. The density is determined from the difference in the distance value between the two objects and the sensor, and the smaller the difference in the distance value is, the higher the density is, and the greater the density is, the lower the density is.

In step 646, the EPW value included in the collected data is determined.

In step 650, it is determined whether the slope, density, and EPW determined in steps 642, 644, and 646 satisfy a predefined criterion (condition). If the condition is met, the object is determined to represent the ground (step 662), and if not, the object may be determined to be an obstacle (step 664). In one embodiment, it can be determined as a paper surface when at least one of a slope, a density, and an EPW condition is satisfied. In another embodiment, when all three conditions are satisfied, the object can be determined as a ground surface, Ground data can be filtered.

At step 670, the process ends. However, as described above in connection with FIG. 5, the filtered result of the ground data can be displayed or transmitted to another device for display. In addition, the data acquired in step 620 may be transferred between devices before being stored in a predetermined storage in step 630. [ That is, the flowchart shown in FIG. 6 is exemplary and some steps corresponding to the above description may be omitted or added at the level of those skilled in the art.

In this specification, elements represented as means for performing a specific function encompass any way of performing a particular function, and these elements may be implemented as a combination of circuit elements performing a specific function, or software for performing a specific function May include any form of software, including firmware, microcode, etc., coupled with suitable circuitry to perform.

Reference throughout this specification to &quot; one embodiment &quot; of the principles of the invention and various modifications of such expression in connection with this embodiment means that a particular feature, structure, characteristic or the like is included in at least one embodiment of the principles of the invention it means. Thus, the appearances of the phrase &quot; in one embodiment &quot; and any other variation disclosed throughout this specification are not necessarily all referring to the same embodiment.

It is to be understood that all embodiments and conditional statements disclosed herein are intended to assist one skilled in the art to understand the principles and concepts of the present invention to those skilled in the art, It will be understood that the invention may be embodied in various other forms without departing from the spirit or essential characteristics thereof. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

400: ground data filtering device
410:
420:
430:
440:

Claims (12)

An apparatus for filtering ground surface data,
A sensor for receiving data about an object around the vehicle;
A storage unit for storing the received data and a predefined criterion; And
And a processing unit for comparing the received data with the predefined criterion to filter data for the object that is determined to represent the ground of the object around the vehicle. The method according to claim 1,
The sensor emits one or more beams for sensing the object,
Each of the beams comprising a plurality of different layers. 3. The method of claim 2,
Wherein the processing unit obtains a slope from data of objects detected in two adjacent layers among the layers,
And determines that the sensed object represents a ground surface when the slope corresponds to the predefined criterion. 3. The method of claim 2,
Wherein the processing unit obtains the distance between the sensor and the sensed object from the data of the object sensed in two adjacent layers of the layer,
And determines that the sensed object represents a ground surface when the difference value of the obtained distance corresponds to the predefined criterion. The method according to claim 1,
The predefined criterion is an EPW value representing a road,
Wherein the processing unit determines that the object represents a ground when the EPW value included in the received data corresponds to the predefined criterion. 3. The method of claim 2,
Wherein the predefined criterion comprises a reference angle, a reference distance difference, and a reference EPW value representing the road,
The processing unit may calculate a slope, a difference in distance to each object, and an EPW value included in the received data from the data of the objects detected in two layers adjacent to each other, And comparing the reference EPW value with the reference EPW value to filter data for the object if it is determined that the object represents a ground in all cases. A method for a vehicle system to filter ground surface data,
Receiving data about an object around the vehicle using a sensor;
Storing the received data in a storage unit;
Comparing the received data with a predefined criterion; And
And filtering the data determined to represent the ground of the object based on the comparison result. 8. The method of claim 7,
Wherein the sensor emits one or more beams for sensing the object, each of the beams comprising a plurality of different layers. 9. The method of claim 8,
Wherein the comparing comprises:
Obtaining a slope from data on objects sensed in two adjacent layers among the layers; And
And determining that the sensed object represents a ground surface if the slope corresponds to the predefined criterion. 9. The method of claim 8,
Wherein the comparing comprises:
Obtaining a distance between the sensor and the sensed object from data for an object sensed in two adjacent layers of the layer; And
And determining that the sensed object represents a ground surface if the difference value of the obtained distance corresponds to the predefined criterion. 8. The method of claim 7,
The predefined criterion is an EPW value representing a road,
Wherein the comparing comprises determining that the object represents a ground if the EPW value included in the received data corresponds to the predefined criterion. 9. The method of claim 8,
Wherein the predefined criterion comprises a reference angle, a reference distance difference, and a reference EPW value representing the road,
Wherein the comparing comprises:
The EPW value included in the received data and the slope, the distance difference between the objects, and the EPW value from the data of the objects sensed in two layers adjacent to each other are referred to as the reference angle, With a value; And
Determining that the object represents a ground if the inclination, the distance difference for each object, and the EPW values included in the received data satisfy the reference angle, the reference distance difference, and the reference EPW value, &Lt; / RTI &gt;

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