Fusing 2D Uncertainty and 3D Cues for Monocular Body Pose Estimation.

Most recent approaches to monocular 3D human pose estimation rely on Deep Learning. They typically involve training a network to regress from an image to either 3D joint coordinates directly, or 2D joint locations from which the 3D coordinates are inferred by a model-fitting procedure. The former takes advantage of 3D cues present in the images but rarely models uncertainty. By contrast, the latter often models 2D uncertainty, for example in the form of joint location heatmaps, but discards all the image information, such as texture, shading and depth cues, in the fitting step. In this paper, we therefore propose to jointly model 2D uncertainty and leverage 3D image cues in a regression framework for monocular 3D human pose estimation. To this end, we introduce a novel two-stream deep architecture. One stream focuses on modeling uncertainty via probability maps of 2D joint locations and the other exploits 3D cues by directly acting on the image. We then study different approaches to fusing their outputs to obtain the final 3D prediction. Our experiments evidence in particular that our late-fusion mechanism improves upon the state-of-the-art by a large margin on standard 3D human pose estimation benchmarks.