Research Projects and Interests
Lisa Streit, Ph.D


My current research interests are focused on modelling and rendering of complex natural scenes.   There are many interesting research issues in this area including how to manage enormous amounts of detail as well as how to edit, modify and create complex natural scenes easily, effectively and efficiently.  This area of research often involves many disciplines.  The natural sciences such as physics and biology are involved in both understanding what it is to be modelled and verifying the approach, tools and techniques developed.  Also, in addition to computer graphics optimizations and algorithms, human computer interaction is involved in designing the tools correctly and again verifying their usefulness.  And finally, often approaches, tools and techniques are adopted from traditional illustration for assistance in visualizing and managing large amounts of detail.

Here is a small selection of the projects I have been involved in - all of which overlap in some fashion with my current interests:

Importance Halftoning
 Importance Driven Halftoning

My M.Sc. work focused on distribution of drawing primitives to preserve tone.  The technique is image-based and concentrated on distribution of black and white primitives and thus is considered a halftoning technique.  There are three main parameters: number of drawing primitives, type of drawing primitive and orientation of drawing primitive.  By altering these three parameters a wide variety of interesting "non-photorealistic" type results can be generated.
Fast Distribution
 Fast Primitive Distribution for Illustration

This project uses a probability density function to distribute primitives in a scale-independent real-time fashion.  As an image based approach it computes the probability density function (PDF) from the original image.  Then using a set of precomputed uniformly distributed points, they are redistributed according to this PDF, to construct a distribution of primitives which accurately portrays the tone of the original image.  This method can be used for both high quality printed results and lower resolution interactive display while preserving frame-to-frame coherence.

Wing
 Modelling of Feather Coat Morphogenesis for Computer Graphics

My Ph.D. dissertation work is on the modelling of feather coat changes.  Not only does this involve modelling the feather coat, but modelling individual and collective changes of the feathers as they grow and the feather coat develops.  The method is based on a carefully constructed model of an individual feather.  This model not only allows for creation of a wide range of feather types, but also can automatically create a continuum of feather type variations.  This continuum of variation is used to construct the feather coat in which every feather is slightly different.  The model also provides a nice framework for determining feather-to-feather collisions and inter-penetrations which are required to "pack" the feathers into the final coat.  Finally the individual feather model easily is able to simulate growth of a feather which is the used to simulate feather moult (loss and regrowth) .  Using sequences of feather moult and a set of defined "feather tracts"  morphogenesis of feather coat is simulated.
Plant VariationPlant Variation
 Modelling of Plant Variation
I am currently working on a project to create plant variation which not only improves the realism of the model by modelling natural variation, but also creates a methodology for producing a large collection of plants.   The collection would then be composed of plants that look similar, yet not the same, while preserving the biological correctness of the model.


This page is always under construction!!!  Please check back again soon!