http://www.kevinbeason.com/worklog Latest personal graphics developments Tue, 09 Jun 2009 18:53:28 +0000 http://backend.userland.com/rss092 en [gallery link="file"] Bunny model available here. Ajax bust available here (thanks jotero!). Bunny scene was under 3 hours, Ajax scene was 8 hours. The Cubo prism model is available here. For comparison, here is a proper rendering by luxrender. The prism shows off a new feature, spectral rendering. I used 20,000,000 photons ... http://www.kevinbeason.com/worklog/2009/06/06/dispersion-and-spectral-filtering/ [gallery link="file"] Fixed lots of bugs in my Ashikhmin & Shirley and Schlick BRDF's. Schlick anisotropic is still not 100% correct. Added explicit BRDF calculation for both BRDF's, allowing for light sampling in addition to BRDF importance sampling. This helped a great deal with small light sources like the sun. To ... http://www.kevinbeason.com/worklog/2009/06/03/151/ [gallery link="file" columns="2"] Here are the results from some distance field intersection experiments. Inspired by slisesix by Inigo Quilez. A better explanation is on my reading list. I also posted these on ompf. A single sample at 1024x768 takes about 6 seconds on a 2.4GHz Q6600 quad core CPU. Intersection works by stepping ... http://www.kevinbeason.com/worklog/2009/06/03/distance-field-experiments/ [gallery link="file"] Added Ashikhmin & Shirley's Anisotropic Phong BRDF and Schlick's BRDF (the '94 paper) support for pure path tracing (implicit light paths only). My Schlick BRDF is probably broken. Adding these entailed abstracting a BRDF interface class, implementing importance sampling and computing BRDF/PDF. The daylight image is after sunset for ... http://www.kevinbeason.com/worklog/2009/03/20/glossy-reflections/ [caption id="attachment_88" align="alignnone" width="400" caption="Chromium, Copper, Iron, Lithium, Nickel, Silicon, Tungsten"][/caption] Inspired by this beauty I set out for rendering with "measured reflectance" values. FreeSnell comes with spectral data for a variety of materials in a series of .nk files, including the index of refraction (n), the extinction coefficient (k, aka absorbtion), ... http://www.kevinbeason.com/worklog/2009/03/20/measured-reflectance/ Another lazy update. This work is from the middle of 2008. First image shows a failed attempt at rendering a displacement mapped triangle mesh. I tried to implement a variation on Interactive Smooth and Curved Shell Mapping (Jeschke et al.) (shown) but my variation was a failure. I also looked at ... http://www.kevinbeason.com/worklog/2009/02/03/heightfield-and-media-rendering/ Finally releasing a little project I've been working on. A small project, although I spent an insane amount of time tweaking it. My hope is that it can serve as a concise reference to anyone wondering what's involved in a basic global illumination renderer. Honestly, since I don't explain the ... http://www.kevinbeason.com/worklog/2008/11/08/smallpt-global-illumination-in-99-lines-of-c/ Another stab at Julia quaternion set, from March. In April I added support for indexed face sets, resulting in fantastic memory savings. Here are test renders of a 7 million and a 28 million polygon model, respectively. Lucy, the 28M tri model, required a fair amount of swap on my ... http://www.kevinbeason.com/worklog/2008/11/08/45/ I was really inspired by the cool images lycium and greenhybrid were making using the sky model by Preetham et al., so in March I read the paper again and overcame my laziness and gag reflex at the spaghetti mess of equations, and hacked together the sky and sun light ... http://www.kevinbeason.com/worklog/2008/10/26/preetham-et-el-sun-and-sky-light-model/ I fixed some simple bugs in the absorption of photons and along rays 6 months ago. The first image is from a debugging session for this. Second image shows a cognac glass with fixed absorption, and also  a text label in the bottom right corner that is automatically added now. ... http://www.kevinbeason.com/worklog/2008/10/20/fixed-absorption-of-photons-and-rays/