Egocentric Mapping of Body Surface Constraints

Abstract

The relative location of human body parts often materializes the semantics of on-going actions, intentions and even emotions expressed, or performed, by a human being. However, traditional methods of performance animation fail to correctly and automatically map the semantics of performer postures involving self-body contacts onto characters with different sizes and proportions. Our method proposes an egocentric normalization of the body-part relative distances to preserve the consistency of self contacts for a large variety of human-like target characters. Egocentric coordinates are character independent and encode the whole posture space, i.e., it ensures the continuity of the motion with and without self-contacts. We can transfer classes of complex postures involving multiple interacting limb segments by preserving their spatial order without depending on temporal coherence. The mapping process exploits a low-cost constraint relaxation technique relying on analytic inverse kinematics; thus, we can achieve online performance animation. We demonstrate our approach on a variety of characters and compare it with the state of the art in online retargeting with a user study. Overall, our method performs better than the state of the art, especially when the proportions of the animated character deviate from those of the performer.

Visuo-tactile congruency influences the body schema during full body ownership illusion

“…While this procedure does install visuo-tactile congruency in the pre-defined use case, it cannot be easily generalized to other forms of self-contact. Molla, Debarba, and Boulic (2018) solved the problem more generally by defining positions in space with regards to egocentric coordinates as seen from individual bodies with specific size and proportions. While this approach can transfer body postures seamlessly between a wide range of different body shapes, the approach used in the present study furthermore extends to providing congruent touch with external objects and is comparatively easy to set up.…”

Inverse Kinematics Techniques in Computer Graphics: A Survey

“…In this direction, it is essential to study methods that automatically adapt skeletons undergoing complex deformations into different input meshes, preserving the essence of motion naturally and without oscillations (e.g. [MGDB17]). They should also be able to re-establish violated constraints that may occur.…”

Impact of Self-Contacts on Perceived Pose Equivalences

“…an egocentric normalization of the body part relative distances [Molla et al(2018)], or an external graph connecting body segments [Baciu and Iu(2006)]. This approach is well illustrated by the interaction mesh proposed by Ho et al Ho10spatial.…”