Ok, it seems I need to go and defend my new predilection renderer. 
Guerilla is the kind of renderer born with sweat of productions. It actually exists since many years (five if I remember well) but has only go public this month.
How could we summary what Guerilla is? Mmmh…
For me, it’s a “turnkey Katana + Arnold combo”.
For those who don’t know Katana, it’s a non destructive lighting workflow (IMHO, non destructive workflow is the futur of lighting but that’s another debate).
From the rendering side, it’s a production CPU path tracer.
So, why Guerilla rocks (yeah, I can’t be more objective…).
I had the oportunity to work on the integration of Katana for a studio. I was very happy because Katana has a very good architecture and provide a way to do what I actually spend month to integrate in a single software.
This is the market part as after few month I must admit it’s a nighmare. Katana is a “core” something almost empty and you need a lot of developpers to make something interesting with it. I was a little disapointed as the promise was good.
Then I discovered Guerilla. The lighting supervisor here at Digital District make me huge training on it and I’ve also been able to discuss with devs about how it work under the hood and… Yeah… It’s how lighting should be in 2013:
You get a scene structure as an enter of your graph and you apply modification with nodes without change anything in the “input”.
So you can light recurscively. like:
- Every object has standard shader.
- Every object with “wood” tag have my wood parameters.
- Every shaders with “metal” tag have my metal parameters.
- Then you set “diffuse” parameter of the shader will have this map, “reflection” will have this map (or value).
- etc…
- And after you start to tweak, group by group, object by object to have the look you want.
You want to modify every metalic parts of your scene? No problem, just go up in you graph and modify. You can duplicate your node to avoid break something.
I’ve seen this workflow in many “middle to big” studios but it was always in-house software and Katana is expensive and unuseable without a lot of dev.
Guerilla is the only one to provide this workflow without need any line of script.
If you have often to deal with huge assets with a lot of objects, you should defenetly have a look to guerilla.
If you are interested about what I’was talking about (about non destructive workflows) I write a mail on the Appleseed (a very good open source renderer) mailing list to discuss about “what I consider to be a modern lighting workflow”: https://groups.google.com/forum/#!searchin/appleseed-dev/Few$20Feedbacks/appleseed-dev/bENTdNVosD0/dhw5JATX9qEJ
PS: I’m not an active BlenderArtist member, I know it can be strange to have peoples just booming about a subject. I’m actually very humble and hope my comment will be informative because Guerilla is not what we could call “an usual renderer”.
PS2: I need to find time to purpose videos to explain how to “efficiently” use this renderer (actually, if you only use rendergraph, you use it efficiently).
