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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Automatic Reconstruction and Web Visualization of Complex PDE Shapes

Pang, M., Sheng, Y., Gonzalez Castro, Gabriela, Sourin, A., Ugail, Hassan January 2010 (has links)
No / Various Partial Differential Equations (PDE) have been used in computer graphics for approximating surfaces of geometric shapes by finding solutions to PDEs subject to suitable boundary conditions. The PDE boundary conditions are defined as 3D curves on the surface of the shapes. We propose how to automatically derive these curves as boundaries of curved patches on the surface of the original polygon mesh. The analytic solution to the PDE used throughout this work is fully determined by finding a set of coefficients associated with parametric functions according to the particular set of boundary conditions. The PDE coefficients require an order of magnitude smaller space compared to the original polygon data and can be interactively rendered with different level of detail. It allows for an efficient exchange of the PDE shapes in 3D Cyber worlds and their web visualization. In this paper we analyze and formulate the requirements for extracting suitable boundary conditions, describe the algorithm for the automatic deriving of the boundary curves, and present its implementation as a part of the function-based extension of VRML and X3D.
2

Cyclic animation using Partial differential Equations

Gonzalez Castro, Gabriela, Athanasopoulos, Michael, Ugail, Hassan, Willis, P., Sheng, Y January 2010 (has links)
Yes / This work presents an efficient and fast method for achieving cyclic animation using Partial Differential Equations (PDEs). The boundary-value nature associ- ated with elliptic PDEs offers a fast analytic solution technique for setting up a framework for this type of animation. The surface of a given character is thus cre- ated from a set of pre-determined curves, which are used as boundary conditions so that a number of PDEs can be solved. Two different approaches to cyclic ani- mation are presented here. The first consists of using attaching the set of curves to a skeletal system hold- ing the animation for cyclic motions linked to a set mathematical expressions, the second one exploits the spine associated with the analytic solution of the PDE as a driving mechanism to achieve cyclic animation, which is also manipulated mathematically. The first of these approaches is implemented within a framework related to cyclic motions inherent to human-like char- acters, whereas the spine-based approach is focused on modelling the undulatory movement observed in fish when swimming. The proposed method is fast and ac- curate. Additionally, the animation can be either used in the PDE-based surface representation of the model or transferred to the original mesh model by means of a point to point map. Thus, the user is offered with the choice of using either of these two animation repre- sentations of the same object, the selection depends on the computing resources such as storage and memory capacity associated with each particular application.
3

Characterization of micro-scale surface features using partial differential equations

Gonzalez Castro, Gabriela, Spares, Robert, Ugail, Hassan, Whiteside, Benjamin R., Sweeney, John January 2010 (has links)
No / Mass production of components with micro and nano scale surface features is known as micromoulding and is very sensitive to a number of variables that can cause important changes in the surface geometry of the components. The surface itself is regarded as a key element in determining the product's functionality and as such must be subject to thorough quality control procedures. To that end, a number of surface measurement techniques have been employed namely, White Light Interferometry (WLI) and Atomic Force Microscopy (AMF), whose resulting data is given in the form of large and rather unmanageable Cartesian point clouds. This work uses Partial Differential Equations (PDEs) as means for characterizing efficiently the surfaces associated with these data sets. This is carried out by solving the Biharmonic equation subject to a set of boundary conditions describing outer surface contours extracted from the raw measurement data. Design parameters are expressed as a function of the coefficients associated with the analytic solution of the Biharmonic equation and are then compared against the design parameters describing an ideal surface profile. Thus, the technique proposed here offers means for quality assessment using compressed data sets.
4

PDE-based Facial Animation: Making the Complex Simple

Sheng, Y., Willis, P., Gonzalez Castro, Gabriela, Ugail, Hassan January 2008 (has links)
Yes / Direct parameterisation is among the most widely used facial animation techniques but requires complicated ways to animate face models which have complex topology. This paper develops a simple solution by introducing a PDE-based facial animation scheme. Using a PDE face model means we only need to animate a group of boundary curves without using any other conventional surface interpolation algorithms. We describe the basis of the method and show results from a practical implementation. / EPSRC
5

A survey of partial differential equations in geometric design

Gonzalez Castro, Gabriela, Ugail, Hassan, Willis, P., Palmer, Ian J. January 2008 (has links)
Yes / Computer aided geometric design is an area where the improvement of surface generation techniques is an everlasting demand since faster and more accurate geometric models are required. Traditional methods for generating surfaces were initially mainly based upon interpolation algorithms. Recently, partial differential equations (PDE) were introduced as a valuable tool for geometric modelling since they offer a number of features from which these areas can benefit. This work summarises the uses given to PDE surfaces as a surface generation technique together
6

On the development of an Interactive talking head system

Athanasopoulos, Michael, Ugail, Hassan, Gonzalez Castro, Gabriela January 2010 (has links)
No / In this work we propose a talking head system for animating facial expressions using a template face generated from partial differential equations (PDE). It uses a set of pre configured curves to calculate an internal template surface face. This surface is then used to associate various facial features with a given 3D face object. Motion retargeting is then used to transfer the deformations in these areas from the template to the target object. The procedure is continued until all the expressions in the database are calculated and transferred to the target 3D human face object. Additionally the system interacts with the user using an artificial intelligence (AI) chatter bot to generate response from a given text. Speech and facial animation are synchronized using the Microsoft Speech API, where the response from the AI bot is converted to speech.
7

Cyclic animation of a human body using PDE surfaces

Athanasopoulos, Michael, Gonzalez Castro, Gabriela, Ugail, Hassan January 2009 (has links)
No / In this work we propose a modelling technique for producing cyclic motions of human body. The surface of the human body has been created from a set of pre-configured curves that were used as the set of boundary conditions to solve a number of partial differential equations (PDE). These boundary curves are attached to a skeletal system that holds the animation for cyclic motions. An important function of the method described here is the use of mathematical expressions within Maya software for generating the cyclic motion leading to a very realistic movement. Thus, the user can interactively manipulate the position and movement of various body parts to achieve various cyclic motions. Finally the animation can be transferred to either the original mesh model from where the boundary curves associated with the PDE surface were extracted or to another mesh model with equivalent topology.
8

Surface profiling of micro-scale surface features using Partial Differential Equations

Gonzalez Castro, Gabriela, Spares, Robert, Ugail, Hassan, Whiteside, Benjamin R., Sweeney, John January 2010 (has links)
No
9

Surface profiling of micro-scale structures using partial differential equation

Gonzalez Castro, Gabriela, Spares, Robert, Ugail, Hassan, Whiteside, Benjamin R., Sweeney, John January 2010 (has links)
No
10

On the spine of a PDE surface

Ugail, Hassan January 2003 (has links)
yes / The spine of an object is an entity that can characterise the object¿s topology and describes the object by a lower dimension. It has an intuitive appeal for supporting geometric modelling operations. The aim of this paper is to show how a spine for a PDE surface can be generated. For the purpose of the work presented here an analytic solution form for the chosen PDE is utilised. It is shown that the spine of the PDE surface is then computed as a by-product of this analytic solution. This paper also discusses how the of a PDE surface can be used to manipulate the shape. The solution technique adopted here caters for periodic surfaces with general boundary conditions allowing the possibility of the spine based shape manipulation for a wide variety of free-form PDE surface shapes.

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