Francisco A. Madera

A Hybrid Bounding Volume Algorithm to Detect Collisions between Deformable Objects

An algorithm to detect collisions between both rigid and deformable objects is presented. The approach exploits benefits of a Bounding Volume Hierarchy (BVH) and a Feature-based method. The BVH decomposes the three dimensional polygonal objects into a hierarchy of spheres. The lowest level of the hierarchy is formed utilising spheres which bound 1-rings surrounding each vertex of the original mesh. Spatial coherence is exploited during construction to ensure that adjacent 1-rings are joined first. This promotes tighter bounding volumes as the objects deform. Experiments were carried out to analyse the performance of the method when varying the BVH construction to consider octrees and binary trees. To illustrate the enhancement the approach provides it has been compared against standard Sphere and Axis-aligned Bounding Volume Hierarchies.

Detecting Self-Collisions Using a Hybrid Bounding Volume Algorithm

A discrete collision detection algorithm to detect self-collisions between deformable objects is presented, this is built up using a Bounding Volume Hierarchy (BVH) and a Feature-based method. The deformations are represented by the features of the mesh, which are withinthe bounding volumes and consequently the updating time for the BVH is reduced. The algorithm compares the minimum bounded geometry, the 1-ring, with the other spheres of the hierarchy in order to cull away Bounding Volumes (BV) that are far apart. The 3D objects utilised are surface-based and are deformed by warping, control points of splines, and a mass-spring model.

Collision Detection for Deformable Objects using Octrees

We present an algorithm for collision detection between multiple deformable objects translating in a large environment. We use Spatial Partitioning to subdivide the scene and a Bounding Volume Hierarchy to decompose the objects, using octrees in both cases. The algorithm is divided in two parts, the Broad and Narrow Phases, with objects that can be rigid or deformable. In the Broad Phase, an octree is used to partition the scene and cull away the objects Bounding Volumes that are distant. In the Narrow Phase, a hierarchical decomposition of Axis Aligned Bounding Boxes or spheres is employed to reduce the number of primitives in the pairwise comparisons. In summary this work is a general-purpose collision detection technique for performing real time collision detection of deformable bodies in interactive 3D applications.

A Distance Hierarchy to Detect Collisions Between Deformable Objects

To detect collisions between deformable objects we introduce an algorithm that computes the closest distances between certain feature points defined in their meshes. The strategy is to divide the objects into regions and to define a representative vertex that serves to compute the distance to the regions of the other objects. Having obtained the closest regions between two objects, we proceed to explore these regions by expanding them and detecting the closest sub-regions. We handle a hierarchy of regions and distances where the first level contains n1 regions, each one is divided into n2 sub-regions, and so on. A collision is obtained when the distance between two vertices in the last level of the tree is less than a predefined value e. The advantage of our algorithm is that we can follow the deformation of the surface with the representative vertices defined in the hierarchy.

Operating System Simulator to Translate Assembler Code to Machine Code

We analysed and implemented an Operating System software simulator to translate assembler code into machine code. The simulator is a computer program of a virtual machine which contains a computer simplified computer architecture and a memory manage module. The simulator allows users to implement routines in order to extend several functionalities such as memory management, control processing, and any other Operating System role. The simulator can also be employed to make different practices to help in the computers architecture understanding.

Hexagonal Prism: A Geometric Primitive for Architecture Design

We study the geometric features of the hexagonal prism and show some designs to be used in architectural geometry. Motivated by the architecture model built in [1], we propose several geometrical designs using the hexagonal prism as the basic primitive. We focus on the geometrical patterns of the hexagonal prism,we pursuit to identify those patterns that space dictates and describe how these patterns are manifested in mathematics and in computer graphics.

Self-collision Detection using Sphere Chains

An algorithm to detect self-collisions in a human object is presented. We proposed to approximate the human object by spheres, which are placed inside the object mesh to fill the correspondent volume. We introduce the concept of sphere chain, a set of joined spheres which contains some regions of the human mesh. The object is approximated by several chains in the preprocessing stage to be prepared for the running stage to perform the collision detection.