Matthew J. Avalos


Lately ...

I've been working in the Computer Graphics Group in the Computer Science Dept at Caltech under David Laidlaw . My emphasis has been on volume visualization, volume rendering and mri data acquisition optimization. Here are some published images I've made.

CV

Please check out my resume to see what I've been doing all these years.

Caltech Graphics Group Efforts

Volume rendering

One of the first thing I did at gg (pronounce gee-gee for graphics group) was to implement a volume ray tracer module for an object based ray tracer David wrote for a class. (He was a graduate student back then). David outlined an algorithm that allowed for ray reflection as well as attenuation. This allowed for some translucency effects. Several images created this way were published in the SIGGRAPH technical slide set.

MRI Parameter Optimization

Here is a synopsis of the MRI parameter optimizer. Four people were involved: David Laidlaw, Mark Motague, Eric Ahrens and myself. I was responsible for writing code to implement the model that David and Eric refined for samples in an MRI machine, to extract sample statistics, to simulate the MRI data acquisition process, and to use that simulation to choose the best parameters that satisfy various constraints like minimizing collection time and noise, and maximizing contrast. David and Monty wrote Perl script to get data to and from the MRI spectrometer, and Eric provided samples to place in the machine and spectrometer/Bruker system expertise

Painting Metaphor

Another visualization effort championed by David was using painting, especially the impressionists, as a metaphore to visualize 2 or 3D multi-valued data. The basic idea is to map those extra values onto brush stroke characteristics. So, for instance, velocity would be mapped to brush stroke size and orientation, or tensor anisotropy could be mapped to the brush stroke opacity. To implement this system, David chose to work on AVS (Advanced Visual Systems) because it was flexible enough to easily experiment with various mappings by hooking up some initial data to various modules, the last one of which would display the final rendering. I ended up writing several AVS modules to generate and process and paint brush strokes onto a canvas.

Contact Info.

Some files and stuff .
Here's my page of links , which would be mostly useless to anyone who isn't me.
avalos@gg.caltech.edu.