Brick Map and Micropolygon Displacement as Renderman

[stilgarna]

Brick map system like renderman for Global and Abiant Occlusion...

Micro polygon displacement as Renderman...

If you wish...

Is irradiance map using this system ???

Bye...

[studioDIM]

It sure is.
Displacement IS taken into full account by GI, provided the displaced details is large enough to grant it some attention from the GI solution, or that the method used to calculate GI is accurate enough.

This, if i got the spirit of your message right...

EDIT: i think i didn't , after all, lol
Lele

[cpnichols]

Re: Brick Map and Micropolygon Displacement as Renderman

Brick map system like renderman for Global and Abiant Occlusion...

Micro polygon displacement as Renderman...

If you wish...

Is irradiance map using this system ???

Bye...

You will find that the irradiance map system that Vray has is so efficient at finding good solutions that you don't need brickmaps or even ambient occlusion. You will throw it all away and use straight GI will color bouncing. It is like asking for a bigger hand crank on your car to start it when Vray is offering a you an electric starter.

As far as micropoly is concerned. Two things to note.

1 - Renderman is a Reyes rendering engine that converts everything to micropolies... at a shading rate of 1 every pixel is a polygon... this is a very different way of working. So the concept of a micorpolygon in the renderman way is completely wrong for rendering engines like mental ray, vray, etc... Reyes rendering is probably the downfall of renderman's raytracing as it ends up having do with so many polys. While it is fine and good for scanline (which is what renderman is) it is a nightmare for raytracing.
2 - Vray does its own version of micropoly displacement as well as Subd. It can subdivid the geo in world space or screen space. When doing it in screen space, it is similar to micropoly system (conceptually) of renderman. Mentalray does something similar.

[Morbid Angel]

chris, then how is it that render man is so fast with mtd? or is it becuase there is no raytracing going on?

[studioDIM]

maybe because it's reyes, so it's very efficient discarding what it doesn't need.
In fact it does seem to crawl when any raytracing is enabled, also because of the "rejection" being a lot less efficient (relfection, refractions, raycast shadows and so on).

Or so i gather :P

Chris has definitely more first hand knowledge than I do.

The Mr solution, though, it's extremely fast and very good especially when mixed with moblur.
And as for Rman is under the scanline realm.
It's a lot faster when combined with raytracing, though, than Rman.
Probably because Mr developed a solid raytracer/scanline hybrid first, and then added on the screen-space micropolys, rather than the other way around like for Rman.

Lele

[cpnichols]

chris, then how is it that render man is so fast with mtd? or is it becuase there is no raytracing going on?

Oh yeah... no raytracing on that or in the subD or nurbs either. Builds the MP as the bucket goes into it... Keep in mind that you need to take into account the displacement bounds because of that. All things considered the raytracing in renderman is very fast, it is the fact that it needs to do it with a reyes architecture in my mind that is killing it. Things like AO and Brickmaps have to be reverse engeneered into the process just to be able to do both.

[Morbid Angel]

so having said that, how would you make photo realistic lighting in rman?
like i mean match daylight lighting reflections etc?

[joconnell]

Most rman lighters tend to avoid it where possible by using reflection maps that are as close to the scene they're mimicking as possible but if there's obvious contact between objects then they resort to raytracing. They us a kind of ibl technique too where they use a blurred reflection map of the environment as one pass and use an ao pass to control it. This is then blended with key / rim light passes to build up the effect.

[Morbid Angel]

in other words, pain and suffering....

[cpnichols]

For sure... I have used this analogy a lot, but lighting in renderman is much more like paint by numbers while lighting in with GI and IBL is a lot more light photography or cinematography.

[studioDIM]

For sure... I have used this analogy a lot, but lighting in renderman is much more like paint by numbers while lighting in with GI and IBL is a lot more light photography or cinematography.

Quite some analogy, Chris.

Why not thinking of RMan like that old, rich, bitchy uncle we'd all want to be safely stowed in the closet for good, but that keeps banging loudly at the closet door to reclaim some more fresh air?

I should stop wasting myself on saturday nights, i think...

Lele

[vlado]

Re: Brick Map and Micropolygon Displacement as Renderman

Micro polygon displacement as Renderman...

This is not a very good idea for a raytracer. Further on, V-Ray already does a fairly good job at displacement.

Brick map system like renderman for Global and Abiant Occlusion...

The method used by V-Ray does a somewhat better job at preserving details in the GI, whereas brick maps tend to blur things quite a bit - which is one of the reasons it is suggested to use it for secondary bounces only.

Best regards,
Vlado

[Morbid Angel]

excuse me, but what is brick map?

[joconnell]

Seems to be another lighting caching method like irmaps - https://renderman.pixar.com/products...announced.html

[Morbid Angel]

renderman is grean an all...
but imo anything thats done in it can be done just as well in vray.