Laser point cloud loopback detection method and system based on triangular pyramid local descriptor

Abstract

The invention provides a laser point cloud loopback detection method and system based on triangular pyramid local descriptors, relates to the technical field of loopback detection, is used for retrieving a loopback frame of a current key frame from a key frame time sequence, and comprises the following steps: constructing a global descriptor and a triangular pyramid local descriptor of each key frame in the key frame time sequence; based on the global descriptor, roughly searching a preliminary candidate loopback frame set from the key frame time sequence; on the basis of the triangular pyramid local descriptors, a final candidate loopback frame set is accurately searched from the preliminary candidate loopback frame set; screening the loopback frame of the current key frame from the final candidate loopback frame set through geometric verification and validity judgment; wherein the triangular pyramid local descriptor is obtained by performing density clustering on the point cloud of the key frame based on the points in the neighborhood, constructing a triangular pyramid by using the clustering result, and taking the information code of the triangular pyramid as the triangular pyramid local descriptor of the key frame. The method has the advantages of high precision, strong robustness, simple calculation and the like.

Claims

1. A laser point cloud loop detection method based on a triangular pyramid local descriptor, characterized in that: Used to retrieve the loop frame of the current keyframe from the keyframe sequence, including: Construct a global descriptor and a triangular pyramid local descriptor for each key frame in the key frame sequence; Based on the global descriptor, a preliminary candidate loop frame set is roughly searched from the key frame sequence; Based on the triangular pyramid local descriptor, the final candidate loop frame set is precisely searched from the preliminary candidate loop frame set; Through geometric verification and validity judgment, the loop frame of the current key frame is selected from the final candidate loop frame set as the final laser point cloud loop detection result; The triangular pyramid local descriptor is based on the number of points in the neighborhood, density clustering is performed on the point cloud of the key frame, a triangular pyramid is constructed using the clustering result, and the information of the triangular pyramid is encoded as the triangular pyramid local descriptor of the key frame.

2. The laser point cloud loop detection method based on triangular pyramid local descriptor according to claim 1, characterized in that: The global descriptor divides the point cloud of the key frame into regions, encodes information in all regions, and calculates the feature value of each region. The feature values ​​of all regions constitute the global descriptor of the key frame.

3. The laser point cloud loop detection method based on triangular pyramid local descriptor according to claim 1, characterized in that: The density clustering of the point cloud of the key frame is based on the distance between two points, the number of points in the neighborhood of each point is calculated, and the points in the point cloud of the key frame are screened and grouped using a preset point count threshold to obtain multiple clusters.

4. The laser point cloud loop detection method based on triangular pyramid local descriptor as claimed in claim 3, characterized in that: The method of constructing a triangular pyramid using clustering results is based on a global descriptor to determine the feature points of each cluster. The feature points of every three clusters form a base triangle of a triangular pyramid, and the laser radar center O is used as the vertex of the triangular pyramid, thereby obtaining a plurality of triangular pyramids.

5. The laser point cloud loop detection method based on triangular pyramid local descriptor according to claim 1, characterized in that: The rough search is specifically as follows: Using the ring coding function, construct the feature density vector of each key frame; Based on the feature density vector, calculate the cosine distance between the current key frame and other key frames in the key frame set; The key frames whose distances meet the preset conditions are selected from the key frame set to form a preliminary candidate loop frame set for the current key frame.

6. The laser point cloud loop detection method based on triangular pyramid local descriptor according to claim 1, characterized in that: The precise search is specifically: Using the triangular pyramid structure information in the triangular pyramid local descriptor, the hash key value of each candidate loop frame in the preliminary candidate loop frame set is calculated, and the candidate loop frames are screened by comparing the hash key value of the current key frame with the hash key value of each candidate loop frame; The candidate loop frames after the hash key value filtering are further screened using the Jaccard similarity coefficient, and the candidate loop frames that are finally retained constitute the final candidate loop frame set.

7. A laser point cloud loop detection system based on a triangular pyramid local descriptor, characterized in that: Used to retrieve the loop frame of the current keyframe from the keyframe sequence, including: The descriptor construction module is configured to: construct a global descriptor and a triangular pyramid local descriptor for each key frame in the key frame sequence; The coarse search module is configured to: coarsely search a preliminary candidate loop frame set from the key frame sequence based on the global descriptor; The fine search module is configured to: based on the triangular pyramid local descriptor, finely search out a final candidate loop frame set from the preliminary candidate loop frame set; The final screening module is configured to: screen out the loop frame of the current key frame from the final candidate loop frame set as the final laser point cloud loop detection result through geometric verification and validity judgment; The triangular pyramid local descriptor is based on the number of points in the neighborhood, density clustering is performed on the point cloud of the key frame, a triangular pyramid is constructed using the clustering result, and the information of the triangular pyramid is encoded as the triangular pyramid local descriptor of the key frame.

8. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the laser point cloud loop closure detection method based on a triangular pyramid local descriptor according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by the processor, the laser point cloud loop closure detection method based on the triangular pyramid local descriptor as described in any one of claims 1 to 6 is implemented.

10. An electronic device, characterized in that: include: A processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes the laser point cloud loop detection method based on the triangular pyramid local descriptor as described in any one of claims 1-6.

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