A Distance-Based Approach for Human Posture Simulations

Abstract

Abstract-Human-like characters can be modeled by suitable skeletal structures, which basically consist in trees where edges represent bones and vertices are joints between two adjacent bones. Motion is then defined as variations of the joints' configuration (i.e., partial rotations) over time, which also influences joint positions. However, this representation does not allow to easily represent the relationship between joints that are not directly connected by a bone. This work is therefore based on the premise that variations of the relative distances between such joints are important to represent complex human motions. While the former representations are currently used in practice for playing and analyzing motions, the latter can help in modeling a new class of problems where the relationships in human motions need to be simulated. Our main interest in this work is in adapting previously captured human postures (one frame of a given motion) with the aim of satisfying a certain number of geometrical constraints, which turn out to be easily definable in terms of distances. We present a novel procedure for approximating the relative inter-joint distances for skeletal structures having arbitrary features and respecting a predefined posture. This set of inter-joint distances defines an instance of the Distance Geometry Problem (DGP), that we tackle with a non-monotone spectral gradient method.

Feature Selection in Time-Series Motion Databases

“…For every motion, together with some information related to rotation angles between body parts (which can be easily extracted from BVH files), we also consider relative distances between joint pairs. Some recent studies, in fact, have shown that relative distances can play an important role in the representation of human motions [6]. As Fig.…”

Introducing the Interaction Distance in the context of Distance Geometry for Human Motions

“…When the animations are represented by functions having the form of equ. (1), the motion adaptation problem can be formulated as follows [2,17]. Let be the initial animation of ( , ), given in terms of absolute vertex positions.…”

“…Some initial studies where the motion adaptation problem is formulated as a dynDGP can be found in [2,15,17]. However, these studies pointed out some limitations in the use of the Euclidean distance for this particular application.…”

“…This article focuses on a particular application of the dynDGP, where the main interest is in analyzing human motions through the study of animated skeletal structures which resemble the human body [20]. Some initial works have shown that tools for distance geometry can be employed in this context [2,17], but they consider, as in the majority of the applications in distance geometry, the Euclidean distance as a metric.…”

An application-based characterization of dynamical distance geometry problems

“…This is a very delicate step, because the inclusion of large changes in the modified distances may cause large distance incompatibilities, and spoil the simulations. One possible technique for modifying the distances related to pairs {u, v} ∈ E S in accordance with new skeletal structure was recently presented in [1,23]. Some preliminary results can be viewed in a video clip associated to the paper [1] (downloadable from the conference website).…”