Geometric Modelling

Porosity determination of jersey structure

by Sofien BENLTOUFA

Halo Matrix Geo-Spatial 3D Mapping and Positions System

by Michael Weaver

Halo Matrix (patent # 61/404,639) is a Geo-Spatial 3D Mapping and Positions System that defines an 3D mapping surface... more Halo Matrix (patent # 61/404,639) is a Geo-Spatial 3D Mapping and Positions System that defines an 3D mapping surface containing an approximation region in air space; capturing a sequence of depth maps over distance and time of of the aircraft in relation to its geo-spatial position, combinatorial networks and geometric network spacing; processing the depth maps in order to detect a direction and speed of movement of the aircraft as the aircraft passes through the triangulated area; and communicating this aircraft's position responsively to the detected direction and speed in relationship to other aircraft's, communication towers and satellite positioning.

Modeling lobed leaves

by Peter MacMurchy

The use of subdivision surfaces in the modeling of plants

by Peter MacMurchy

M.Sc. Thesis from 2004

Plants and plant organs are commonly modeled using skeletal techniques. Plant structure is then described in terms of... more Plants and plant organs are commonly modeled using skeletal techniques. Plant structure is then described in terms of axes, around which limb surfaces are built using standard geometric modeling techniques, such as generalized cylinders or implicit surfaces. In this research, an alternative, based on the use of subdivision techniques, is described. The approach is to build a simple polygon mesh around the skeleton and use a surface subdivision algorithm to get a smooth surface. Special attention is given to the modeling of surfaces surrounding branching points. It is shown that subdivision surfaces provide a useful alternative to approaches based on implicit surfaces. The method is illustrated using models of tree branches and compound leaves.

The use of subdivision surfaces in the modeling of plants [microform]

by Peter MacMurchy

Thesis, as submitted to the University of Calgary library

Plants and plant organs are commonly modeled using skeletal techniques. Plant structure is then described in terms of... more Plants and plant organs are commonly modeled using skeletal techniques. Plant structure is then described in terms of axes, around which limb surfaces are built using standard geometric modeling techniques, such as generalized cylinders or implicit surfaces. In this research, an alternative, based on the use of subdivision techniques, is described. The approach is to build a simple polygon mesh around the skeleton and use a surface subdivision algorithm to get a smooth surface. Special attention is given to the modeling of surfaces surrounding branching points. It is shown that subdivision surfaces provide a useful alternative to approaches based on implicit surfaces. The method is illustrated using models of tree branches and compound leaves.

Big Integers for GIS: Testing the Viability of Arbitrary Precision Arithmetic for GIS Geometry

by Rizwan Bulbul

A definitive programming approach to the implementation of CAD software

by Meurig Beynon

(co-authored by A.J.Cartwright) Intell. CAD Systems II: Implementation Issues, Springer-Verlag, 126-45, 1989

This paper outlines an approach to the implementation of CAD systems that makes use of a programming paradigm based... more This paper outlines an approach to the implementation of CAD systems that makes use of a programming paradigm based upon definitions ("definitive programming").

It departs from previous research on "pure definitive notations" - special-purpose notations for interaction - and proposes a general-purpose programming model based upon definitive principles. This model is examined as a possible basis for the development of an integrated framework within which to address the broader issues of a design support environment, including constraint handling and user-interface management. This gives a new perspective on the use of definitive principles for interaction in which the emphasis is upon interpreting a family of definitions as one of many possible "intelligent views" of an interactive system. It also establishes a closer relationship between the definitive programming approach to CAD and the study of CAD from an AI perspective than was previously evident.

The design of an appropriate definitive notation for geometric modelling is a fundamental aspect of the application of definitive principles to CAD software. An appropriate basis for such a notation is presented in an Appendix.

Remote interactive walkthrough of city models

by Julien Perret

The FL-system: a functional L-system for procedural geometric modeling

by Julien Perret

Modélisation d'environnements urbains virtuels

by Julien Perret

A Panorama on Multiscale Geometric Representations, Intertwining Spatial, Directional and Frequency Selectivity

by Laurent Duval

An overview on two-dimensional wavelet transforms and their generalizations.
Co-authored with Laurent Jacques, Caroline Chaux and Gabriel Peyré
Accepted in 'Signal Processing"

The richness of natural images makes the quest for optimal representations in image processing and computer vision... more The richness of natural images makes the quest for optimal representations in image processing and computer vision challenging. The latter observation has not prevented the design of image representations, which trade off between efficiency and complexity, while achieving accurate rendering of smooth regions as well as reproducing faithful contours and textures. The most recent ones, proposed in the past decade, share an hybrid heritage highlighting the multiscale and oriented nature of edges and patterns in images. This paper presents a panorama of the aforementioned literature on decompositions in multiscale, multi-orientation bases or dictionaries. They typically exhibit redundancy to improve sparsity in the transformed domain and sometimes its invariance with respect to simple geometric deformations (translation, rotation). Oriented multiscale dictionaries extend traditional wavelet processing and may offer rotation invariance. Highly redundant dictionaries require specific algorithms to simplify the search for an efficient (sparse) representation. We also discuss the extension of multiscale geometric decompositions to non-Euclidean domains such as the sphere or arbitrary meshed surfaces. The etymology of panorama suggests an overview, based on a choice of partially overlapping "pictures". We hope that this paper will contribute to the appreciation and apprehension of a stream of current research directions in image understanding.