Update 4

Since last posting, we read a new series of papers regarding flame simulation, investigated a photon mapper extension of Radiance, and acquired book references and image scans from Professor Holod.

In anticipation of our spectroradiometer readings tomorrow, we finished reading Alan Chalmers' papers on illumination of archaelogical site reconstructions. In the papers, the authors discussed how they conducted light measurements with the spectroradiometer, so we passed on the papers to Cory. We also acquired a new perspective regarding light simulation- while we had initially assumed that we would light the scene with fluid simulations of candle flames, it was illuminating to read how Chalmers' team dealt the lack of light source representation for flame lighting in Radiance. In Chalmers' "Realistic Visualisation of the Pompeii Frescoes" and "High Fidelity Lighting of Knossos" papers, they overcame this problem by simulating candlelight first with a series of illum spheres (illum is a material type in Radiance that is an invisible light source) and later with light voxels tied to data taken from flame video clips.

Nancy looked into the other flame simulation papers listed in last week's entry, as well as a few new ones that were suggested to us by Dr. Badler. The most helpful and interesting paper was "Enhanced Illumination of Reconstructed Dynamic Environments using a Real-Time Flame Model" by Bridault-Louchez, Leblond, and Rousselle. This paper divided all flame simulation papers into three categories: physically based methods, approximation methods, and methods that incorporated real world data. Since we are interested in something that is more physically accurate, this eliminates approximation methods. The methods in Chalmers' papers can be categorized into the third category; Bridault-Louchez et al add that the downside to these methods is that while being high quality, they do not allow "interactive animations." We're not quite sure what "interactive" means, although it is important to be able to render images of the mosque from several different viewpoints. As for physically based methods, the paper mentions that "Physically Based Modeling and Animation of Fire" by Nguyen et al was the most realistic method in 2006; drawbacks include complexity and long computation times.

The paper then goes on to explain their method for simulating candlelight in archaelogical site reconstructions, which includes simulating flames with the Navier-Stokes equation, using particles as control points to create a NURBS surface, and using a spectophotometer to capture the photometric distribution of a real flame. The results are good and this method seems to have been designed specifically with lighting archaelogical reconstructions in mind, but we are unsure about its complexity, and plan to ask about this method and other papers' methods at the meeting on Thursday. As for the other papers, "Three Dimensional Tomographic Reconstruction of the Luminosity Distribution of a Combustion Flame" and "Digital Imaging-Based Three-Dimensional Characterization of Flame Front Structures in a Turbulent Flame" constructed a 3D flame based on 2D images captured on cameras, and "Extending the Photon Mapping Method for Realistic Rendering of Hot Gaseous Fluids" involved adding flash, flash reflection and emission maps in addition to the global and caustics maps usually involved in photon mapping. Hopefully, we'll be able to decide on the best path to take in regards to flame simulation on Thursday.

In our ongoing struggle to get a handle on Radiance, we discovered that there is a photon mapper extension of Radiance 3.7. Given our interest in rendering the scenes with both Radiance and a photon mapper, we decided to investigate the extension over the weekend. I made several attempts to either add the photon mapper code to an already installed version of Radiance or to install a version of Radiance compiled with the photon mapper code. However, due to compilation errors and our limited experience in Linux, we have yet to get the photon mapper code working. We plan to talk to friends of ours who have experience with Linux so that we can get this resolved by tomorrow.

Lastly, after many missed connections over the course of the last two weeks, we finally managed to receive a fuller set of glass lamp images and book references from Professor Holod. During the span of two meetings, Professor Holod gave us a set of relevant image files and provided direction on how she believes the lamps should be placed and lit inside the mosque. She also wrote out a list of books on reserve in the Fisher Library. We will stop by there tomorrow to scan select pages from Meditation of Ornament, Glass of the Sultans and Cairo of the Mamluks.