Scan Line / Ray Tracing Advice


Currently having to write a paper on scanline conversion and ray tracing. Was wondering if anyone could give me some information on which techniques are used in the big animation productions such as Toy Story, Monsters Inc, Finiding Nemo, Incredibles etc.

Any information about actually how long they took to render. Ive read info about 6hrs average fram and 24 frames a second but by my calculations that makes it like 88 years for a 90 minute film.

Would like web sites so i can reference the information as well if thats possible.

Thanks in Advance


Well what i know for sure is that pixar used renderman for the rendering, probarly in house build shaders.

You can get some infor on their website, although it won’t be that much.

I’ve read somewhere that a few frames in finding nemo took up to 95+ hours of rendering one frame, but you have to consider that pixar probarly has a 100 if mayby not a 500+ cpu renderfarm(s). :slight_smile:


I’d guess their farms probably more like 2-3000 cpu’s at least.

All film work is scanline-rendered, mostly using Pixar’s Photorealistic RenderMan (PRMan), although some stuff is done in Mental Image’s mental ray. Both are hybrid scanline/raytrace renderers, which means they do scanline rendering for what the camera sees, and then shoot rays for secondary illumination (GI/reflections/refractions etc). Not sure exactly how mental ray renders things, but PRMan doesn’t exactly do scanline conversion, instead it does stochastic sampling of micropolygons. For mroe information, read “Advanced RenderMan”, or Cook, Catmull and Carpenter’s paper, available here:

I think frame times depend on the studio, but for most cases I think 2-12 hours a frame would be about average. The word is Pixar render everything in camera, which explains their frame times. Companies like ILM render some hideously complex stuff so they’ll have pretty high frame times too, especially when you add up all the different passes (just imagine how long those huge space battles in episode III will take).

Aside from the direct rendering time, there’s also the offline dynamics computation to take into account as well: hair cloth and fluids are behind-the-scenes costs but can eat up huge resources.


I had read and article about them a few months ago that said they used 1024 computer in there renderfarm, and each one has 2 gigs of ram.

“The Emeryville, Calif.-based film studio is replacing servers from Sun in its “render farm”–a bank of servers that fuses artists’ images into finished film frames–with eight new blade servers from RackSaver. In all, the blade system contains 1,024 Intel 2.8GHz Xeon processors, and it runs the open-source Linux operating system. Pixar installed the RackSaver system over the last six months and will use it to develop its next film, “The Incredibles,” which will likely hit theaters in 2004.”

"The render farm, at Pixar’s Emeryville, California, headquarters, also has two terabytes of memory :eek:and 60 terabytes of disk space. ":eek::eek:

That was at one of intel’s conferences I think. I know i’ve seen some pretty specific info about this…i’ll update if I find it.




Well all the movies that you mentioned are Pixar movies. And since Pixar owns renderman, that is pretty much what they used. Renderman is primarily a scanline rendering engine that just recently adapted raytracing capabilities. PDI, that did such movies as Shrek 1 and 2, and Antz, uses their own rendering engine which is has great raytracing abilities. Bluesky, which did Ice Age, anf the soon to come out Robots, uses an amazing raytracing engine, again their own, and I have been envyous of it all along.

Now in terms of rendering times, usually on a feature film, I would say that your goal is to average no more then 2 hours a frame. That is a VERY general statement, and it can very a lot per studio, and per project. I hear rumors that some of the frames done at Pixar went as high as 24 hours for a frame. But that was a long time ago. The key is computers… and lots of them. The more you get, the more time you can afford per frame. That is why people call renderings that take a long time “expensive.”


Is the renderer used by Blue sky studios a little sister or the twin sister of BMRT, which has magically disappeared? Is it commercially available somewhere? It must be a renderman compliant renderer, I mean, most good renderers are partly compatible with the renderman specification.

btw, Brazil was used extensively on The Core, Hellboy(the cars are partly extra’s and the car he hits is a Brazil car.Indistinguishable!!!), and some fantasy movie coming up. Check out their website . It has a very fast HDRI rendering solution, way faster than what I’ve seen by other systems, but I haven’t seen PRMan at work though.


BMRT was made by Larry Gritz, currently working at NVIDIA. And I heard that BMRT “has magically disappeared” beacause NVIDA is now its owner, and is like a in-house production.

I think the render engine from blueSky Studios is called AIR. At least i read that in an article. Correct me if I’m wrong.



Not all… MentalRay has nothing to do with Renderman.


BMRT along with its commercial descendant Entropy were withdrawn as part of a legal settlement between Exluna (who made Entropy and was co-founded by Larry Gritz) and Pixar. Pixar claimed that Entropy contained code derived from patented Pixar technology and sued. Exluna was bought by Nvidia and the case was settled. The downside was that both software renderers Larry Gritz was involved with went too.

BMRT was my introduction to the wonderful world of RenderMan and I was an Entropy user too. [nostalgia mode] Those were the days… [/nostalgia mode]



No it isn’t available to buy and as far as i know has nothing to do with renderman or BMRT (out of interest what leads you to beleive it might be?) PDI also used their own in house renderer for ants and both shrek films. When you say ‘partly compatible’ are you refering to Gelato?

Anyway, based on what I’ve read in the past, my understanding is that blue skys renderer is unique in that it’s a pure raytracer (i.e. not scanline or hybrid). I think this is why all the fur for ice age was done on texture mapped cards.



The renderer at Blue Sky studios is called CGI Studio

AIR is a completely different (and RenderMan compatible) renderer from Scott Iverson . I think it has been used at The Orphanage, Frantic Films and Animal Logic.



rendermaniac thanks for correcting me. But I read somewhere that AIR is used, or was used for some time, by a big studio, don’t know which though. :slight_smile:


This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.