TECHNICAL FIELD

The subject matter described herein relates, in general, to systems and methods for reducing LiDAR points, and, in particular, to using a grid and distances from a camera to reduce LiDAR points in an image.

BACKGROUND

LiDAR sensors are popular sensors for use in autonomous and semi-autonomous vehicles. A LiDAR sensor measures the distance to a target by illuminating the target with a pulse laser, and measuring the reflected pulses. Differences in return times and wavelengths for the pulses can then be used to generate a 3D representation of the target. Often, LiDAR sensors include a plurality of lasers, with each laser outputting a pulse laser at a different angle.

While LiDAR sensors are very sensitive and can provide a very accurate representation of a target, there are drawbacks associated with LiDAR sensors. One drawback in the sheer amount of data (called points) generated by the LiDAR sensor. Each point may have an associated distance from the LiDAR sensor. LiDAR points are often used for a variety of post-processing tasks such as shape recognition, direction detection, and shape-matching with previous frames. When the number of such points are large, such post-processing tasks can be become bogged down and may take a long time to execute. Because such tasks are time sensitive, there is a need to reduce the number of points that are provided by LiDAR sensors without compromising the overall effectiveness of the LiDAR sensors.

SUMMARY

In one embodiment, a system for removing LiDAR points is provided. An image is received from a camera and a plurality of points is received from a LiDAR sensor. The points are placed on the image based on coordinates associated with each point. The image is divided into a plurality of cells by placing a grid over the image. For each cell, a threshold is calculated based on the minimum distance between the points in the cell and the camera. The threshold may control how many points are allowed to remain in each cell. After calculating the thresholds, points are removed from each cell until the number of points in each cell do not exceed the threshold for the cell. The image and/or the reduced plurality of points are then used to provide one or more vehicle functions.

As will be described further below, the system solves may of the problems associated with large numbers of LiDAR points. First, by removing LiDAR points from cells, the overall number of LiDAR points is reduced leading to faster processing and resource usage by vehicle functions that rely on the LiDAR points. Second, because the threshold for each cell is based on the distance between the points in the cell and the camera, cells that are closer to the camera will have more points removed than cells that are farther from the camera. Because LiDAR points tend to be denser at a closer distance, removing points from close cells may have less effect on the vehicle functions that use the points.

In an embodiment, a system for reducing LiDAR points for a vehicle is provided. The system includes one or more processors and a memory communicably coupled to the one or more processors. The system further includes a reduction module including instructions that when executed by the one or more processors cause the one or more processors to: receive an image from a camera associated with the vehicle; receive a plurality of points from a LiDAR sensor associated with the vehicle, wherein each point of the plurality of points is associated with a position in the image; divide the image into a plurality of cells, wherein each point of the plurality of points is associated with a cell of the plurality of cells based on the position of the point in the image; for each cell of the plurality of cells, calculate a threshold for the cell based on the points associated with cell; for each cell of the plurality of cells, delete points associated with the cell until a number of points associated with the cell satisfies the threshold; and use the remaining points for one or more vehicle functions.

In an embodiment, a method for reducing LiDAR points is provided. The method includes: receiving an image from a camera associated with a vehicle; receiving a plurality of points from a LiDAR sensor associated with the vehicle, wherein each point of the plurality of points is associated with a position in the image; dividing the image into a plurality of cells, wherein each point of the plurality of points is associated with a cell of the plurality of cells based on the position of the point in the image; for each cell of the plurality of cells, calculating a threshold for the cell based on the points associated with cell; for each cell of the plurality of cells, deleting points associated with the cell until a number of points associated with the cell satisfies the threshold; and using the remaining points and the image for one or more vehicle functions.

In an embodiment, a non-transitory computer-readable medium for reducing LiDAR points is provided. The medium including instructions that when executed by one or more processors cause the one or more processors to: receive an image from a camera associated with a vehicle; receive a plurality of points from a LiDAR sensor associated with the vehicle, wherein each point of the plurality of points is associated with a position in the image; divide the image into a plurality of cells, wherein each point of the plurality of points is associated with a cell of the plurality of cells based on the position of the point in the image; for each cell of the plurality of cells, calculate a threshold for the cell based on the points associated with cell; for each cell of the plurality of cells, delete points associated with the cell until a number of points associated with the cell satisfies the threshold; and use the remaining points for one or more vehicle functions.

