Pedestrian velocity obstacles: pedestrian simulation through reasoning in velocity space

We live in a populous world. Furthermore, as social animals, we participate in activities which draw us together into shared spaces -- office buildings, city sidewalks, parks, events (e.g., religious, sporting, or political), etc. Models that can predict how crowds of humans behave in such settings would be valuable in allowing us to analyze the designs for novel environments and anticipate issues with space utility and safety. They would also better enable robots to safely work in a common environment with humans. Furthermore, credible simulation of crowds of humans would allow us to populate virtual worlds, helping to increase the immersive properties of virtual reality or entertainment applications. We propose a new model for pedestrian crowd simulation: Pedestrian Velocity Obstacles (PedVO). PedVO is based on Optimal Reciprocal Collision Avoidance (ORCA), a local navigation algorithm for computing optimal feasible velocities which simultaneously avoid collisions while still allowing the agents to progress toward their individual goals. PedVO extends ORCA by introducing new models of pedestrian behavior and relationships in conjunction with a modified geometric optimization planning technique to efficiently simulate agents with improved human-like behaviors. PedVO introduces asymmetric relationships between agents through two complementary techniques: Composite Agents and Right of Way. The former exploits the underlying collision avoidance mechanism to encode abstract factors and the latter modifies the optimization algorithm's constraint definition to enforce asymmetric coordination. PedVO further changes the optimization algorithm to more fully encode the agent's knowledge of its environment, allowing the agent to make more intelligent decisions, leading to a better utilization of space and improved flow. PedVO incorporates a new model, which works in conjunction with the local planning algorithm, to introduce a ubiquitous density-sensitive behavior observed in human crowds -- the so-called "fundamental diagram." We also provide a physically-plausible, interactive model for simulating walking motion to support the computed agent trajectories. We evaluate these techniques by simulating various scenarios, such as pedestrian experiments and a challenging real-world scenario: simulating the performance of the Tawaf, an aspect of the Muslim Hajj.Doctor of Philosoph

Multilayer representation for geological information systems

En esta tesis se propone el uso de la Representación de Terrenos Basada en Stacks (SBRT, de sus siglas en inglés) para datos geológicos volumétricos. Esta estructura de datos codifica estructuras geológicas representadas como stacks utilizando una compacta representación de datos. A continuación, hemos formalizado la SBRT con un esquema basado en la teoría de geo-átomos para proporcionar una definición precisa y determinar sus propiedades. Esta tesis también introduce una nueva estructura de datos llamada QuadStack, mejorando los resultados de compresión proporcionados por la SBRT al aprovechar la redundancia de información que a menudo se encuentra en los datos distribuidos por capas. También se han proporcionado métodos de visualización para estas representaciones basados en el conocido algoritmo de visualización raycasting. Al mantener los datos en todo momento en la memoria de la GPU de forma compacta, los métodos propuestos son lo suficientemente rápidos como para proporcionar velocidades de visualización interactivas.In this thesis we propose the use of the Stack-Based Representation of Terrains (SBRT) for volumetric geological data. This data structure encodes geological structures represented as stacks using a compact data representation. The SBRT is further formalized with a framework based on the geo-atom theory to provide a precise definition and determine its properties. Also, we introduce QuadStacks, a novel data structure that improves the compression results provided by the SBRT, by exploiting in its data arrangement the redundancy often found in layered dataset. This thesis also provides direct visualization methods for the SBR and QuadStacks based on the well-known raycasting algorithm. By keeping the whole dataset in the GPU in a compact way, the methods are fast enough to provide real-time frame rates.Tesis Univ. Jaén. Departamento de Informática. Leída el 19 de septiembre de 2019

Computer graphics simulation of organic and inorganic optical and morphological appearance changes.

Organic bodies are subject to internal biological, chemical and physical processes as well as environmental interactions after death, which cause significant structural and optical changes. Simulating corpse decomposition and the environmental effects on its surface can help improve the realism of computer generated scenes and provide the impression of a living, dynamic environment. The aim of this doctorate thesis is to simulate post mortem processes of the human body and their visual effects on its appearance. The proposed method is divided into three processes; surface weathering due to environmental activities, livor mortis and natural mummification by desiccation. The decomposing body is modelled by a layered model consisting of a tetrahedral mesh representing the volume and a high resolution triangle surface mesh representing the skin. A particle-based surface weathering approach is employed to add environmental effects. The particles transport substances that are deposited on the object’s surface. A novel, biologically-inspired blood pooling simulation is used to recreate the physical processes of livor mortis and its visual effects on the corpse’s appearance. For the mummification, a physically-based approach is used to simulate the moisture diffusion process inside the object and the resulting de- formations of the volume and skin. In order to simulate the colouration changes associated with livor mortis and mummification, a chemically-based layered skin shader that considers time and spatially varying haemoglobin, oxygen and moisture contents is proposed. The suggested approach is able to model changes in the internal structure and the surface appearance of the body that resemble the post mortem processes livor mortis, natural mummification by desiccation and surface weathering. The surface weathering approach is able to add blemishes, such as rust and moss, to an object’s surface while avoiding inconsistencies in deposit sizes and dis- continuities on texture seams. The livor mortis approach is able to model the pink colouration changes caused by blood pooling, pressure induced blanching effects, fixation of hypostasis and the purple discolouration due to oxygen loss in blood. The mummification method is able to reproduce volume shrinkage effects caused by moisture loss, skin wrinkling and skin darkening that are comparable to real mummies

Proceedings of the 7th Sound and Music Computing Conference

Proceedings of the SMC2010 - 7th Sound and Music Computing Conference, July 21st - July 24th 2010