Francisco J. Perales López

A New Method for Detection and Initial Pose Estimation Based on Mumford-Shah Segmentation Functional

In this paper we describe a new method for detection and initial pose estimation of a person in a human computer interaction in an uncontrolled indoor environment. We used the Koepfler-Morel-Solimini mathematical formulation of Mumford-Shah segmentation functional adapted to color images. The idea is to obtain a system to detect the hands and face in a sequence of monocular or binocular images. The skin color is predefined and a procedure is parameterized to segment and recognize the homogeneous regions. Besides, we fit our results to a restriction that the two hands and face must be detected at the same time. We also use a biomechanical restriction to reach this initial estimation. So, the centroid of the blob is computed for every region. We explain the mathematical background segmentation, and region classification (hands, face, head and upper-torso). Finally, we present some interesting results and we implement the algorithm efficiently in order to obtain real time results processing standard video format.

3D Part Recognition Method for Human Motion Analysis

A method for matching sequences from two perspective views of a moving person silhouette is presented. Regular (approximate uniform thickness) parts are detected on an image and a skeleton is generated. A 3D regular region graph is defined to gather possible poses based on the two 2D-regular regions, one for each view, at a given frame. The matching process of 3D graphs with a model graph results in interpretations of the human motion in the scene. The objective of this system is to reconstruct human motion parameters and use the analytical information for synthesis. Experimental results and error analysis are explained when the system is used to drive an avatar.

P3DMA: A Physical 3D Deformable Modelling and Animation System

Animation and Realistic Simulation of a 3D objects elastic deformation is actually an important and challenging feature in applications where three-dimensional object interaction and behaviour is considered or explored. Also, in interactive environments we need a rapid computation of deformations. In this paper we present a prototype of a system for the animation and simulation of elastic objects in an interactive system and under real-time conditions. The approach makes use of the finite elements method (F.E.M) and Elasticity Theory. The simulation is interactively visualized in an Open Inventor environment. Using picking node selection the user can interactively apply forces to objects causing their deformation. The deformations computed with our approach have a physical interpretation based on the mathematical model defined. Furthermore, our algorithms perform with either 2D or 3D problems. Finally, a set of results are presented which demonstrate performance of the proposed system. All programs are written in C++ using POO, VRML and Open Invertor tools. Real time videos can be visualized on web site: http://dmi.uib.es/people/mascport/defweb/dd.html.

Matching a Human Walking Sequence with a VRML Synthetic Model

In this paper we present a specific matching technique based on basic motor patterns between two image sequences taken from different view points and a VRML synthetic human model. The criteria used are part of a generic system for the analysis and synthesis of human motion. The system has two phases: an automatic or interactively supervised analysis phase where the motion is interpreted and a synthesis phase where the original motion is applied to a biomechanical model. The main goal of our approach consists of finding a general solution that could be applied to general motor patterns. We define a set of matching conditions and we describe general-purpose criteria in order to reduce the space of search. The complexity of human motion analysis has led researchers to study new approaches and design more robust techniques for human tracking, detection or reconstruction. Whereas mathematical solutions partially solve this problem, the complexity of the algorithms proposed only serve to limit these solutions for real time purposes or general kind of motion types considered. So, we propose more simple, less general approaches but with a low computational cost. In this case the human model information about the kind of movement to be studied is very important in the process of matching between key-frame images. We also try to develop a system that can, at least in part, overcome the limitations of view dependence.

Elastic Deformations Using Finite Element Methods in Computer Graphic Applications

Deformation tools constitute an important topic in computer animation. This paper shows how we can give an exact value to the basic parameters in a dynamical elastic deformation system based on finite elements for 2D objects. We look for an optimal value for the time step ( Δt ) in the dynamical system, and an optimal area for the basic square finite element of the object. Fine time step adjustment is important to reduce the computational cost of the system, and guarantee the realistic look of the result (final deformation of the object). Then several results from different physical conditions are compared, in order to find a good system of measuring the difference between them. Finally, using this measurement parameter we can relate the size of the finite elements with the error between several deformations of the same object. The deformations are rendered using the Open Inventor application (VRML).