Feature Extraction from Depth Maps for Object Recognition

This paper suggests features for depth image. It said when using HOG with depth images, much improved performance can be made which out-performs standard HOG. 

The below is the impressive statements. 

Two baseline features were used for comparison: standard HOG over the calculated RGB grayscale image itself and HOG using the depth map as a grayscale image. Both of these were intended as baselines, and HOG over the RGB grascale is the only feature in this paper that directly incorporates numerical color data.