Renderman

Data

Type

Info

Pixars Renderman, previously called PRman (photo realistic renderman) is the one renderer. It was here first, and it will stay if all others are gone... It has a long history. First it was developed in the 1970s by Ed Catmull and others. Then Pixar used it to first develop shots like "Knick Knack" or "Wally B". Later it was used for VFX in features movies and finally for full CG movies like Toy Story. Since in the early days the memory was quite expensive and computers had to deal with a tiny amount of ram (compared to nowadays computers), the basic algorithm was based on the principle to create data only if necessary and throw it away as soon as possible. So for any bucket, the geometry is subdivided into subpatches which then are shaded. With this technology only the parts visible in currently rendered buckets had to stay in memory. This worked fine as long as there was no need for raytracing. Rendeman itself worked a long time without raytracing at all. Reflections were faked with mapping or with other tricks. It was calm after newer renderers like mentalray, vray and arnold  appeared. But then Pixar started a new area. They offer a non commercial version. This is a fully functional version, no limits, only in a way you are not allowed to use it commercially. But that's great. Following the common trend to pathtracing, Pixar implemented RIS a path tracer (and bi directional path tracer) for interactive work and final renderings. And of course because it is a path tracer, it trends to produce noise which leads to Pixars Denoise tool. It removes noise from an image without loosing detail information.

Release 21:

The denoiser received GPU support. And Renderman supports OSL now, what is a great thing even if it seems that it cannot yet be used for surface shaders, but texture patterns only. Renderman now ships with the same production shaders which are used by Pixar itself to create their outstanding movies. Lighting system has been rewritten to fit better into modern hardware. New and improved procedural textures are available. It seems that they drop REYES now and concentrate on the pathtracer RIS. This simplifies the workflow because the user has to deal with less parameters. And a lot of other smaller new things have been added. A really nice release.

Release 20:

With version 20 Pixar introduced a Denoiser. It was intially developed by Disney and was used in Big Hero 6 even if this movie was rendered with Disneys own inhouse renderer Hyperion. Renderman now has a better hair marshner based hair shader. Camera imperfections are introduced like lense distortion, vignetting, chromatic aberration to make the image less perfect.

 

Breaking bottle scene review:

To test the breaking bottle scene, I used the brandnew Renderman 21 with Maya2017. Now the REYES mode is completely gone what simplifies rendering a lot. the first impression is good. The previous problem that Renderman light locators were not visible in the Viewport2.0 is gone. Maya lights are ignored. You can create disk, rect, spherical and other lights. They are the same the only difference is the shape. I'd prefer to have one light where I can set the shape. The rest works really fine. Shading an lighting work as expected and I was able to shade my scene quite fast, well it is not really complex so no wonder it works nicely. I used the pathtracer integrator because I wanted to compare better with Arnold and others. To create nice caustics, I can use VCM integrator what is a bidirectional pathtracer which is able to do nice refractive and reflective caustics, I'll add a test as soon as possible.

If you do batchrendering, rib files are exported for the whole sequence in one go as soon as you start the rendering or in batch if you change the settings. Then the prman batch rendering starts with it's own window. Even if this is a more efficient apporach because it avoids the overhead of Maya to Renderman translation and no Maya has to be open during rendering, I prefer one batch process which can be easily controlled.

One thing which I found quite special is that the renderman batch process saves everything in its own directory. This contains all rib files and the final images. I expected them in the projects images directory. Maybe this can be changed in some preferences but I could not find it immediately.

If you have a look at some of the glass shards, it seems that Renderman is much more picky concerning the geometry. There is a flickering in some pieces. I suppose this comes from Houdini which does not export the geometry in a 100% clean way. But I did not encounter these problems in Arnold or ProRender.

The rendering was quite fast and the result does not have much noise any more even without the new GPU powered denoiser.

As usual, the scene file can be downloaded here.

 

Last update: 11.2016