Retrieval and constraint-based human posture reconstruction from a single image

In this study, we present a novel model-based approach to reconstruct the 3D human posture from a single image. The approach is guided by a posture library and a set of constraints. Given a 2D human figure, i.e., a set of labeled body segments and estimated root orientation in the image, a 3D pivotal posture whose 2D projection is similar to the human figure is first retrieved from the posture library. To facilitate the retrieval process, a table-lookup technique is proposed to index postures according to their 2D projections with respect to designated view directions. Next physical and environmental constraints, including segment length ratios, joint angle limits, pivotal posture reference, and feet-floor contact, are automatically applied to reconstruct the 3D posture. Experimental results show the effectiveness of the proposed approach.