Analysis of Irregularities in Human Actions with Volumetric Motion History Images

This paper describes a new 3D motion representation, the Volumetric Motion History Image (VMHI), to be used for the analysis of irregularities in human actions. Such irregularities may occur either in speed or orientation and are strong indicators of the balance abilities and of the confidence level of the subject performing the activity. The proposed VMHI representation overcomes limits of the standard MHI related to motion self-occlusion and speed and is therefore suitable for the visualization and quantification of abnormal motion. This work focuses on the analysis of sway, which is the most common motion irregularity in the studied set of human actions. The sway is visualized and quantified via a user interface using a measure of spatiotemporal surface smoothness, namely the deviation vector. Experimental results show that the deviation vector is a reliable measure for quantifying the deviation of abnormal motion from its corresponding normal motion.