Juan A. Magallon

Drift-Free Real-Time Sequential Mosaicing

We present a sequential mosaicing algorithm for a calibrated rotating camera which can for the first time build drift-free, consistent spherical mosaics in real-time, automatically and seamlessly even when previously viewed parts of the scene are re-visited. Our mosaic is composed of elastic triangular tiles attached to a backbone map of feature directions over the unit sphere built using a sequential EKF SLAM (Extend Kalman Filter Simultaneous Localization And Mapping) approach.This method represents a significant advance on previous mosaicing techniques which either require off-line optimization or which work in real-time but use local alignment of nearby images and ultimately drift. We demonstrate the system’s real-time performance with real-time mosaicing results from sequences with 360 degrees pan. The system shows good global mosaicing ability despite the challenging conditions: hand-held simple low-resolution webcam, varying natural outdoor illumination, and people moving in the scene.

The Evolution of a WILDLAND Forest FIRE FRONT

The rate of the spread and shape of a forest fire front is a problem that has not been thoughtfully studied from a computer graphics perspective. Here, using physically based computer graphics modeling, we propose a model for the simulation of wildland fires over 3D complex terrain. The model is based on conservation laws of energy and species, which includes radiation convection, reaction and natural convection, and takes into account the endothermic and exothermic phases of this kind of phenomenon. As an application, a simulation of a wildland fire in the Ebro basin of Spain is presented. The results are visualized on synthetic imagery, obtained by using the digital model of the studied terrain plus its corresponding images acquired by the Spot 4 and LandSat TM satellites.

Quality Control of an Interpolation Method for Discontinuous Parametric Surfaces

In this paper we study a finite element interpolation method for fitting discontinuous parametric surfaces when the data points are the nodes of a curvilinear grid. Quality control of the interpolating surfaces is also considered, focussing on the display of isophotes and reflection lines using ray tracing techniques. Finally, graphical and numerical examples are given.

Lighting design in low-cost immersive systems

GIGA (the Advanced Computer Graphics Group from the University of Zaragoza) has developed two packages, code-named ALEPH and SICARA3D. Those systems are capable of both calculating light distribution in complex environments, based on a rigorous simulation of the physical phenomena involved, and visualizing the results in a photorealistic way, including models of the HVS (human visual system) implemented in a third package code-named SmiddotEmiddotKmiddotEmiddotR. Our systems support, as a remarkable difference with respect to all other known systems like RADIANCE ([G.J. Ward, (1994)]), a spectral management of lighting magnitudes, instead of working with simple RGB. We have also added to this framework the power of low-cost CAVE immersive systems. With this combination, we include stereoscopy and a collaborative environment to the reliability of the numerical results and the realistic aspect of the imagery

Parallelization of inverse design of luminaire reflectors

This paper presents the parallelization of techniques for the design of reflector shapes from prescribed optical properties (far-field radiance distribution), geometrical constraints and, if available, a user-given initial guess. This is a problem of high importance in the field of Lighting Engineering, more specifically for Luminaire Design. Light propagation inside and outside the optical set must be computed and the resulting radiance distribution compared to the desired one in an iterative process. Constraints on the shape imposed by industry needs must be taken into account, bounding the set of possible shape definitions. A general approach is based on a minimization procedure on the space of possible reflector shapes, starting from a generic or a user-provided shape. This minimization techniques are usually known also as inverse problems, and are very expensive in computational power, requiring a long time to reach a good solution. To reduce this high resource needs we propose a parallel approach, based on SMP and clustering, that can bring the simulation times to a more feasible level.

Geometric and visual modelling of complex stratigraphic structures

Abstract Geologists routinely perform three-dimensional analyzes to understand and describe spatial relationships. The end product of any data analysis obtained from structural or stratigraphic geological studies is usually a set of complex surfaces. The graphic presentation of data is important because it influences the geological interpretation of natural phenomena. The purpose of this paper is to present geometric and visual modelling tools and methods that allow geologists to incorporate geological interpretation during the data input process and automatically obtain a realistic three-dimensional simulation of the real shape of a complex geologic structure. The procedure will also provide a graph for any (cross or oblique) section of the structure. Such displays are particularly useful for people who are not familiar with contour maps to help them “see” unusual or special features and to improve the ability to interpret a map. Geometric modelling of these complex surfaces is based on an interpolation method for discontinuous parametric surfaces using finite elements. Visual modelling is based on photorealistic image synthesis following the ray-tracing method. Our techniques are generic (not tied to a specific program) and discussed in terms of general capabilities (not specific program parameters).