Doctor of Philosophy

dissertationRay tracing presents an efficient rendering algorithm for scientific visualization using common visualization tools and scales with increasingly large geometry counts while allowing for accurate physically-based visualization and analysis, which enables enhanced rendering and new visualization techniques. Interactivity is of great importance for data exploration and analysis in order to gain insight into large-scale data. Increasingly large data sizes are pushing the limits of brute-force rasterization algorithms present in the most widely-used visualization software. Interactive ray tracing presents an alternative rendering solution which scales well on multicore shared memory machines and multinode distributed systems while scaling with increasing geometry counts through logarithmic acceleration structure traversals. Ray tracing within existing tools also provides enhanced rendering options over current implementations, giving users additional insight from better depth cues while also enabling publication-quality rendering and new models of visualization such as replicating photographic visualization techniques

Management and display of four-dimensional environmental data sets using McIDAS

Over the past four years, great strides have been made in the areas of data management and display of 4-D meteorological data sets. A survey was conducted of available and planned 4-D meteorological data sources. The data types were evaluated for their impact on the data management and display system. The requirements were analyzed for data base management generated by the 4-D data display system. The suitability of the existing data base management procedures and file structure were evaluated in light of the new requirements. Where needed, new data base management tools and file procedures were designed and implemented. The quality of the basic 4-D data sets was assured. The interpolation and extrapolation techniques of the 4-D data were investigated. The 4-D data from various sources were combined to make a uniform and consistent data set for display purposes. Data display software was designed to create abstract line graphic 3-D displays. Realistic shaded 3-D displays were created. Animation routines for these displays were developed in order to produce a dynamic 4-D presentation. A prototype dynamic color stereo workstation was implemented. A computer functional design specification was produced based on interactive studies and user feedback

Doctor of Philosophy

dissertationWhile boundary representations, such as nonuniform rational B-spline (NURBS) surfaces, have traditionally well served the needs of the modeling community, they have not seen widespread adoption among the wider engineering discipline. There is a common perception that NURBS are slow to evaluate and complex to implement. Whereas computer-aided design commonly deals with surfaces, the engineering community must deal with materials that have thickness. Traditional visualization techniques have avoided NURBS, and there has been little cross-talk between the rich spline approximation community and the larger engineering field. Recently there has been a strong desire to marry the modeling and analysis phases of the iterative design cycle, be it in car design, turbulent flow simulation around an airfoil, or lighting design. Research has demonstrated that employing a single representation throughout the cycle has key advantages. Furthermore, novel manufacturing techniques employing heterogeneous materials require the introduction of volumetric modeling representations. There is little question that fields such as scientific visualization and mechanical engineering could benefit from the powerful approximation properties of splines. In this dissertation, we remove several hurdles to the application of NURBS to problems in engineering and demonstrate how their unique properties can be leveraged to solve problems of interest

Isosurface modelling of soft objects in computer graphics.

There are many different modelling techniques used in computer graphics to describe a wide range of objects and phenomena. In this thesis, details of research into the isosurface modelling technique are presented. The isosurface technique is used in conjunction with more traditional modelling techniques to describe the objects needed in the different scenes of an animation. The isosurface modelling technique allows the description and animation of objects that would be extremely difficult, or impossible to describe using other methods. The objects suitable for description using isosurface modelling are soft objects. Soft objects merge elegantly with each other, pull apart, bubble, ripple and exhibit a variety of other effects. The representation was studied in three phases of a computer animation project: modelling of the objects; animation of the objects; and the production of the images. The research clarifies and presents many algorithms needed to implement the isosurface representation in an animation system. The creation of a hierarchical computer graphics animation system implementing the isosurface representation is described. The scalar fields defining the isosurfaces are represented using a scalar field description language, created as part of this research, which is automatically generated from the hierarchical description of the scene. This language has many techniques for combining and building the scalar field from a variety of components. Surface attributes of the objects are specified within the graphics system. Techniques are described which allow the handling of these attributes along with the scalar field calculation. Many animation techniques specific to the isosurface representation are presented. By the conclusion of the research, a graphics system was created which elegantly handles the isosurface representation in a wide variety of animation situations. This thesis establishes that isosurface modelling of soft objects is a powerful and useful technique which has wide application in the computer graphics community

Physiological system modelling

Computer graphics has a major impact in our day-to-day life. It is used in diverse areas such as displaying the results of engineering and scientific computations and visualization, producing television commercials and feature films, simulation and analysis of real world problems, computer aided design, graphical user interfaces that increases the communication bandwidth between humans and machines, etc Scientific visualization is a well-established method for analysis of data, originating from scientific computations, simulations or measurements. The development and implementation of the 3Dgen software was developed by the author using OpenGL and C language was presented in this report 3Dgen was used to visualize threedimensional cylindrical models such as pipes and also for limited usage in virtual endoscopy. Using the developed software a model was created using the centreline data input by the user or from the output of some other program, stored in a normal text file. The model was constructed by drawing surface polygons between two adjacent centreline points. The software allows the user to view the internal and external surfaces of the model. The software was designed in such a way that it runs in more than one operating systems with minimal installation procedures Since the size of the software is very small it can be stored in a 1 44 Megabyte floppy diskette. Depending on the processing speed of the PC the software can generate models of any length and size Compared to other packages, 3Dgen has minimal input procedures was able to generate models with smooth bends. It has both modelling and virtual exploration features. For models with sharp bends the software generates an overshoot

Acceleration Techniques for Photo Realistic Computer Generated Integral Images

The research work presented in this thesis has approached the task of accelerating the generation of photo-realistic integral images produced by integral ray tracing. Ray tracing algorithm is a computationally exhaustive algorithm, which spawns one ray or more through each pixel of the pixels forming the image, into the space containing the scene. Ray tracing integral images consumes more processing time than normal images. The unique characteristics of the 3D integral camera model has been analysed and it has been shown that different coherency aspects than normal ray tracing can be investigated in order to accelerate the generation of photo-realistic integral images. The image-space coherence has been analysed describing the relation between rays and projected shadows in the scene rendered. Shadow cache algorithm has been adapted in order to minimise shadow intersection tests in integral ray tracing. Shadow intersection tests make the majority of the intersection tests in ray tracing. Novel pixel-tracing styles are developed uniquely for integral ray tracing to improve the image-space coherence and the performance of the shadow cache algorithm. Acceleration of the photo-realistic integral images generation using the image-space coherence information between shadows and rays in integral ray tracing has been achieved with up to 41 % of time saving. Also, it has been proven that applying the new styles of pixel-tracing does not affect of the scalability of integral ray tracing running over parallel computers. The novel integral reprojection algorithm has been developed uniquely through geometrical analysis of the generation of integral image in order to use the tempo-spatial coherence information within the integral frames. A new derivation of integral projection matrix for projecting points through an axial model of a lenticular lens has been established. Rapid generation of 3D photo-realistic integral frames has been achieved with a speed four times faster than the normal generation

Design and development of a VR system for exploration of medical data using haptic rendering and high quality visualization

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Deep-learning the Latent Space of Light Transport

We suggest a method to directly deep‐learn light transport, i. e., the mapping from a 3D geometry‐illumination‐material configuration to a shaded 2D image. While many previous learning methods have employed 2D convolutional neural networks applied to images, we show for the first time that light transport can be learned directly in 3D. The benefit of 3D over 2D is, that the former can also correctly capture illumination effects related to occluded and/or semi‐transparent geometry. To learn 3D light transport, we represent the 3D scene as an unstructured 3D point cloud, which is later, during rendering, projected to the 2D output image. Thus, we suggest a two‐stage operator comprising a 3D network that first transforms the point cloud into a latent representation, which is later on projected to the 2D output image using a dedicated 3D‐2D network in a second step. We will show that our approach results in improved quality in terms of temporal coherence while retaining most of the computational efficiency of common 2D methods. As a consequence, the proposed two stage‐operator serves as a valuable extension to modern deferred shading approaches