Validating Objective Evaluation Metric: Is Fréchet Motion Distance able to Capture Foot Skating Artifacts ?

Automatically generating character motion is one of the technologies required for virtual reality, graphics, and robotics. Motion synthesis with deep learning is an emerging research topic. A key component of the development of such an algorithm involves the design of a proper objective metric to evaluate the quality and diversity of the synthesized motion dataset, two key factors of the performance of generative models. The Fréchet distance is nowadays a common method to assess this performance. In the motion generation field, the validation of such evaluation methods relies on the computation of the Fréchet distance between embeddings of the ground truth dataset and motion samples polluted by synthetic noise to mimic the artifacts produced by generative algorithms. However, the synthetic noise degradation does not fully represent motion perturbations that are commonly perceived. One of these artifacts is foot skating: the unnatural foot slides on the ground during locomotion. In this work-in-progress paper, we tested how well the Fréchet Motion Distance (FMD), which was proposed in previous works, is able to measure foot skating artifacts, and we found that FMD is not able to measure efficiently the intensity of the skating degradation.