Ive stumbled upon a really good tutorial on pixars website, about renderman 18/19.
http://renderman.pixar.com/view/TheGrandTour [renderman.pixar.com]
It seemed like a really cool looking project, and since prman 19 was not out as non-commercial at the time, i thought how easy/difficult would it be to try and do something like that in houdini.
Now im not a lighter or a shader writer, im an fx td, but this really was a challenge for me and an opportunity to play with pbr and shader building, and i have to say i was blown away by how easy it is to set up the shaders and to get the project rolling.
So ive downloaded all the project files and exported them as alembic and started building the shaders and trying to replicate them the same way the tutorial suggests. Since the project files had textures and models, it was only the shader building part and the lighting on my part. The difference also is that in the tutorial they already have the shading models and they would build the shading network, where i had to do everything.
Sometimes mantrasurface was enough, other times i had to build one in shops from scratch.
I also used the delay load archive as well as houdini instancing geo to try and do grass, since fur wasnt cutting it. The curve render is good but renderman has a setting to make the curves appear like they are rounded, which makes the spec look quite different.
Since i wasnt able to reproduce this (i did try some hacks suggested by odforce crew, it became too complicated and wasnt giving me proper results), i modeled couple of strands myself and instanced it. Final grass count was around 50000000 and it took 8 min to start the render. Im guessing writing the ifd maybe?
Also the new fur system is pretty cool, i had to learn how it works tho since ive never used it before.
The guide hair system is great and i managed to replicate the top hair of the character, since guide hairs were provided with proj files. Sometimes i would have trouble to try and find some attributes that are named differently in maya, but what ive concluded is that there should be a help page illustrating how to properly use fur (something like a quick tutorial). I know there are pages in help trying to do this, however its split on per fur tool basis, and i was kinda looking more for one page to go over every tool, since i would have to navigate back and forth a lot to try and get to information i needed. And i side navigation bar would help quite a lot in help
The rock shader with moss was a fun thing to do, and ive concluded that there is no way that mantrasurface shader can by default provide an ubersystem solution. Multiple times i found myself wanting to have a way to hook a ramp or a noise patter onto a parameter without diving inside and digging thru the connections.Other times i would simply find the guts of the shader too messy and spending more time finding where i should hook something up, so i would just create a shader from scratch. And the mantrasurface model did provide me with enough inside information to figure out how everything worked, so that was very good.
Ive stumbled across some bugs in the meantime and informed sesi thru RFE about them, such as zbrush tangent vector displacement.
All in all it was extremely fun, and very rewarding i would think to go thru this project, and i got to learn some new stuff as well.
Thumbs up for SESI how much they have improved the entire system, tho there is still work to be done. (default ptex map loading in mantrasurface doesnt work due to links from uv)
Here are some images i managed to render let me know what you guys think (i dont know if this should be in WIP section, if so admins please move it):
