Automatic extraction of low-level object motion descriptors

In our previous work, we developed a method to extract low-level elementary motion units (EMU) and elementary reaction units (ERU) for object-based event description, assuming perfect video object segmentation and tracking. This paper features the following contributions. (1) We propose a novel object tracking algorithm for a specific domain. (2) We evaluate the performance of our EMU and ERU extraction system with automatically-computed but imperfect video object information obtained by the proposed tracker. It is assumed that objects for which descriptors are sought for are interactively marked on the initial frame. (3) We extend the description of ERUs to enable better description of low-level reactions. Experimental results are provided to demonstrate each contribution.