PhD thesis

Have a look at my PhD thesis at SFU library (PDF) or check out the slides of the seminar to see what it is about.

Abstract

Visualization techniques are key to leveraging human experience, knowledge, and intuition when establishing a connection between computational models and real world systems. At this interface my dissertation enables effective choices of parameter configurations for different levels of user involvement.

Based on a characterization of several domains of computer experimentation that include a model of biological aggregations, image segmentation methods, and rendering algorithms, I derive a set of requirements to propose Paraglide - a framework for user-driven analysis of parameter effects. One outcome of the workflow I suggest is a partitioning of the continuous space of model configurations into distinct regions of homogenous system behaviour.

To facilitate progressive exploration of a parameter region, I develop a space-filling sampling method by constructing point lattices that contain rotated and scaled versions of themselves. All levels of resolution share a single type of Voronoi polytope, whose volume grows independently of the dimensionality by a chosen integer factor as low as 2.

To optimize rendering time while ensuring image quality when viewing data in a 3-dimensional volume, I perform a Fourier domain analysis of the effect of composing two functions. Based on this, I relax a previous lower bound for a sufficient sampling frequency and apply it to adaptively choose the numerical integration step size in raycasting.

By assigning optical properties to data using a spectral light model, it becomes possible to improve physical realism and to create colour effects that scale the level of distinguishable detail in a visualization.

To help modellers to cope with the freedom in a large design space of synthetic lights and materials, I devise a method that generates a palette of presets that globally optimize user-specified criteria and regularization. This is augmented with two alternative user interfaces to unobtrusively choose a desired mixture.