In this paper, we consider an optimal rate control algorithm for shape coding of emerging MPEG-4 compression system. Current MPEG-4 shape coding consists of two sub-steps; First distortion is introduced by scaling down and up way. Then, second, context-based arithmetic coding is applied. Since the arithmetic coding is \lossless", scaling down and up step is considered as a virtual quantizer. We...

Access to the shape by its exterior is solved using convex hull. Many algorithms have been proposed in that way. This contribution addresses the open problem of the access of the shape by its interior also called convex skull. More precisely, we present approaches in discrete case. Furthermore, a simple algorithm to approximate the maximum convex subset of star-shaped polygons is described.

This paper investigates the problem of optimal lossy encoding of object contours in the Inter mode. Contours are approximated by connected second-order spline segments, each defined by three consecutive control points. Taking into account correlations in the temporal direction, control points are chosen optimally in the rate-distortion (RD) sense. Applying motion to contours in the reference fr...

We propose an approach to accurately detecting two dimensional shapes. The cross-section of the shape boundary is modeled as a step function. We first derive a one-dimensional optimal step edge operator, which minimizes both the noise power and the mean squared error between the input and the filter output. This operator is found to be the derivative of the double exponential (DODE) function. W...

We present a new shape-coding approach, which decouples the shape information into two independent data sets, the skeleton and the distance of the boundary from the skeleton. The major benefit of this approach is that it allows a more flexible trade-off between accuracy of the approximation and bit-allocation cost, and thus, provides the possibility of better performance in the operational rate...

R 3 for a fixed shape orientation. Using a self-dual IPM solver, we show that optimal solutions for large-scale formations (e.g. thousands of robots) can be computed in less than 1 second using a standard desktop PC. We also investigate the computational complexity of our approach by solving the SOCPs using a logarithmic-barrier (central-path following) method. The most computationally expensiv...

The problem of finding the optimal tapering of a free (non-supported) javelin is described and solved. For the optimal javelin, the lowest mode of vibration has the highest possible frequency. With this tapering inner damping will lead to the cessation of the vibration at the fastest possible rate. The javelin is modeled as a beam of uniform material. The differential equations governing the vi...

In this paper, we present a review of our work on rate-distortion based operationally optimal vertex-based lossy shape encoding techniques. We approximate the boundary of a given shape by a low order curve, such as a polygon, and consider the problem of nding the approximation which leads to the smallest distortion for a given number of bits. We also address the dual problem of nding the approx...

A major problem in object oriented video coding and MPEG-4 is the encoding of object boundanes. Traditionally, and within MPEG-4, the encoding of shape and texture information are separate steps (the extraction of shape is not considered by the standards). In this paper, we present a vertex-based shape coding method which is optimal in the operational rate-dstortion sense and takes into account...

Parametric spline models are used extensively in representing and coding planar curves. For many applications, it is desirable to be able to derive the spline representation from a set of sample points of the planar shape. The problem we address in this paper is to nd a cubic spline model to optimally approximate a given planar shape. We solve this problem by treating the control points which d...