http://liar.bramz.net 'LiAR isn't a raytracer' is an open source, cross platform, object-oriented and extendable raytracer written in C++ and Python by Bram de Greve. Tue, 28 Oct 2008 19:45:55 +0000 http://backend.userland.com/rss092 en Christer Ericson, author of Real-Time Collision Detection has written a little article on Plücker coordinates and why they are considered harmful. It's great. I never really understood what all the fuss was about, as I could do the Plücker coord tricks as easily with basic 3D linear algebra ... http://liar.bramz.net/2007/07/17/plucker-coordinates-not-so-good-for-you/ As of 28 June 2007, Sourceforge will decommission the SVN access URLs starting with https://svn.sourceforge.net/svnroot/. They are replaced by URLs with the project names in front. For LiAR, this looks like https://liar.svn.sourceforge.net/svnroot/. The new URL scheme is part of an upgrade of the Subversion access method to ... http://liar.bramz.net/2007/06/12/new-url-for-subversion-access/ We've successfully moved the LiAR home page to http://liar.bramz.net. This should allow us to upload bigger renders, and get better search engine coverage. The old URLs starting with http://liar.sourceforge.net should redirect traffic to the new site so that no links get broken. Share and Enjoy! http://liar.bramz.net/2007/02/08/weve-moved-to-liar-bramz-net/ If you're planning to install Visual Studio 2005 Service Pack 1, keep this in mind: Make sure you have at least three gigs of free space on your C: drive. To be on the safe side, make it four gigs. Windows Update tries to shove this up your arse as a ... http://liar.bramz.net/2007/02/07/things-learnt-while-installing-vs2005-sp1/ While debugging another segmentation fault on linux, I was trying to run LiAR in gdb (actually KDbg). The program crashed somewhere in an allocator, but the reason why was almost impossible to see. The debugging experience was crippled because distutils compiles with full optimization -O3 by default, at ... http://liar.bramz.net/2007/01/29/overriding-default-compiler-options-in-distutils/ When I tried to run a first render in linux, I got a segmentation fault in the photon mapper because there were no lights. Of course, this shouldn't cause a crash (fixed by now), but why were there no lights? I was pretty sure I defined one, and ... http://liar.bramz.net/2007/01/28/shared-libraries-dlopen-and-rtti/ The description of LiAR says: "'LiAR isn't a raytracer' is an open source, cross platform, object-oriented and extendable ray tracer written in C++ and Python by Bram de Greve". However, that's not entirely true since currently, LiAR only runs on the Windows platform. It's time to live up ... http://liar.bramz.net/2007/01/27/the-bumpy-road-to-the-linux-build/ I've added clip mapping (*) to LiAR, which is some sort of alpha channel for surfaces. It can be used to create holes in a surface using a texture. The texture is compared to a threshold to determine where the surface should be removed, so that rays can travel ... http://liar.bramz.net/2007/01/23/clip-mapping/ I'm trying to use the subdivision surfaces I've implemented to get a smoother surface for car i'm rendering for PHD Motorsports. The original model has UV coordinates that need to be interpolated as well. As each triangle is split in four, each edge is split two. I've ... http://liar.bramz.net/2007/01/10/subdivision-surfaces-and-uv-interpolation-problem/ I've implemented subdivision surfaces for the TriangleMesh using the Loop's scheme. Triangles are split in four, and the vertices are weighted using masks to produce a smoother surface. This process is repeated a few times, indicated by the subdivision level. The implementation also supports the concept of creases. If ... http://liar.bramz.net/2006/12/12/loop-subdivision-surfaces/ I've reproduced the older FZR render using the Ashikhmin & Shirley BSDF and the Uffizi Gallery light probe. For the glass of the windows and the head lights, I've implemented a new material called ThinDielectric that acts as a thin (but not very) pane of glass. Given an ... http://liar.bramz.net/2006/12/02/fzr-in-uffizi-and-thin-dielectrics/ It's been more than a month since last update, so it's time for a status report. I've been further playing with photon mapping and some nice shaders. The main additions to the photon mapper itself are the (ir)radiance caching when using the final gather step, and the caustics ... http://liar.bramz.net/2006/11/15/caustics-in-the-cornell-box/ Summer is over (already 20 days since September 21), and as promised, we're back with some more LiAR stuff =) I've been busy with a few things, the main one being the photon mapper. It's not completed yet. Currently we only have a global photon map and a gather ... http://liar.bramz.net/2006/10/10/photon-mapping-with-the-cornell-box/ Hi all, It's been a while since the last update. We can assure you that LiAR isn't dead, but unfortunately we have been through some busy months, and some more are coming up, which puts everything on a hold. So there probably won't be many updates in the next ... http://liar.bramz.net/2006/06/20/summer-break/ My first render using an environment map as skylight ... Using the technique described in Infinite Area Light Source with Importance Sampling by Pharr and Humphreys, it's implemented in a breeze ... (thanks Thomas, for pointing out that article =) (Light probe: Grace Cathedral by Paul Debevec) http://liar.bramz.net/2006/04/26/image-based-lighting/ Today, I noticed there was something seriously wrong with the way local differential geometry was treated by transformation objects. Basically, rendering goes like this: find intersection, find geometry of intersection, get shader at intersection, shade using the geometry. However, currently, if the object being intersected is a transformed ... http://liar.bramz.net/2006/04/20/fixing-transformations-and-local-geometry/ I'm in a bit of a design dilemma right now ... Currently, materials are implemented as shaders. This is similar to the RenderMan Interface. Each material is a piece of code that gets executed when the ray tracer hits the surface, and yields the outgoing radiance (the colour to ... http://liar.bramz.net/2006/04/18/shaders-or-bsdfs/ Today, I've being translating the ever-famous Cornell box to a python module. Of course, I also had to make some render, so here it is. Since I still only have direct lighting (ok ok, I really need to fix that =), the result is not so terrific. ... http://liar.bramz.net/2006/04/17/cornell-box-direct-lighting-only/ Today, I've been playing a bit with area lights ... They are implemented as a scene object scenery.LightArea that takes another scene object as light surface. I'm not entirely happy with it, but here's some tests ... The first one is the good ol' red sphere with a spherical ... http://liar.bramz.net/2006/04/16/area-lights/ We're glad to announce that we've migrated the LiAR source code from the CVS to a Subversion (SVN) repository. SVN is generally available on sourceforge since February, and by making this move, we'll allow for more flexible code management. You can grab the latest code from the repository by the ... http://liar.bramz.net/2006/04/16/subversion/ I've just implemented a RenderTarget called Display which shows the image on screen while being rendered. I've used the almighty PixelToaster to accomplish this, which turned out to be pretty easy. Here's the recurring red sphere on a blue checkerboard plane being rendered in a window: One lesson learned: ... http://liar.bramz.net/2006/03/13/rendertarget-with-pixeltoaster/ It's been a while since my last update. Two months to be exact. What have I been doing in that time? Not that much ... I've been struggling with lights ... How do lights fit in the grand design of a ray tracer? Are they objects? ... http://liar.bramz.net/2006/02/18/blender-export/ A render of the new PHD-Motosports skin for the FZR. Wimz is doing an amazing job on those skins. There's a nice detail you can't see from this point of view: the driver's name with a little Belgian flag. Great! The cars are rendered with depth of field ... http://liar.bramz.net/2005/12/15/phd-motorsports-fzr/ Some time ago, I mentioned I was implementing depth of field in LiAR. Well, I finally managed to code and test it. The following image illustrates the depth of field effect. The left part is rendered by a pinhole camera, the right part by a camera with ... http://liar.bramz.net/2005/12/04/depth-of-field/ This week, I've been mostly rendering ... cars. It's been a while since my last update. I've been rendering cars for PHD-Motorsports. The setup is rather simple. The same triangle mesh is instantiated three times with a different skin. There are three point lights: a pure white ... http://liar.bramz.net/2005/12/03/renders-of-lx6/ LiAR isn't a raytracer is pleased to announce that it has become the official sponsor of PHD-Motorsports, the Ghent-based racing team owned by Victor De Muer. The team is currently competing in the VRL Live For Speed WinterTrophy 2005. Last week, LiAR CEO Bram de Greve was contacted by De ... http://liar.bramz.net/2005/11/22/liar-sponsors-phd-motorsports-team/ A render of a low poly owl modeled by Wim Verbrugghe. The vertex normals are generated using the smoothNormals() function that's now available on TriangleMesh. However, this seems to bugger up the wings, so the wings use face normals instead. http://liar.bramz.net/2005/11/20/snow-owl/ This day, I've been mostly rendering ... bunnies That's right, I can import models in PLY format now. This format is used by the Standford University Computer Graphics Laboratory for its ever-popular 3D Scanning Repository. The importer is written as a python script src/tools/ply.py. There's also an example ... http://liar.bramz.net/2005/11/20/stanford-bunny/ The code for the triangle meshes is to the CVS. There are also a lot of other minor changes. It'll probably take a few hours for the anonymous CVS to catch up though. You will also need to upgrade your LASS installation. http://liar.bramz.net/2005/11/19/triangle-meshes-added-to-cvs/ You can't properly render fast cars without motion blur, can you? Motion blur is something that's already in LiAR's feature set for some time, so I tried it out on the triangle mesh. And here it is ...*drumroll* ... This is a scaled down/cropped version of a 2000x1500 image ... http://liar.bramz.net/2005/11/16/motionblur/