The paper demonstrates that DECAF, which depends on accurate initial keypoint estimates to drive its test-time optimization, produces poor reconstructions when significant occlusion is present. In cases where the hand covers more than half the face, the 2D keypoint estimators (MediaPipe, 3DDFA) fail to produce accurate initial estimates, causing DECAF's iterative fitting to converge to incorrect hand-face relationships. This is shown qualitatively in Figure 8 with several example images.
Evidence
observational
Caveat
Shown qualitatively with a small number of examples in Figure 8; no systematic evaluation over a defined set of occluded cases is reported