1. A method of detecting movement of objects depicted in a lidar point cloud on a device comprising a processor, the method comprising: executing on the processor instructions configured to: identify at least one object represented by a voxel cluster of voxels respectively corresponding to lidar points in the lidar point cloud and sharing an adjacency within a three-dimensional voxel space; for the respective lidar points in the lidar point cloud: associate the lidar point with a selected object, and compare a first position of the lidar point at a first time and a second position of the lidar point at a second time to classify the movement of the lidar point according to the selected object; and for the respective objects, classify the movement of the object according to the movement of the respective lidar points associated with the object.