Fig. 2

Illustration of descriptor principle. (a) Original 3D object, where yellow points represent the keypoints obtained from the surface of the object; (b) The local surface within neighboring space with radius r and centered on keypoint p; (c) Construction of LRF on keypoint p and transformed local points with respect to the LRF, where blue, yellow, and red arrows represent X-, Y-, and Z-axis, respectively; (d) Split space into a set of cubic voxels; (e) Set label for each voxel, where blue voxels and transparent voxels represent label value is 1 and others is 0, respectively; (f) Update the label value of each voxel, where the color depth of the cube represents the size of voxel label value; (g) Output feature of keypoint p by merging label value of each voxel according to particular index coding