preparing scene...whats it doing?

[sjorgens]

hi guys,

I have a large scene rendering, just over 1 million face. I have am using instances, so things are pretty much uinder control.

MY question is that when I go to render in max scanline the preparing scene stage is relatively quick, a matter of seconds actually. On the other hand Vray takes at least a minute maybe more to get past the preparing scene stage.

I know they are completely different in architecture, but what the hell is Vray doing differently thats making it take so long? Is there some way to optimise this? Is it caching geometry to disk, or doing something similar? If so could this be saved?


Just looking for ways to optimise this. Obviously if it is adding alot more time to my renders then I may have to consider using more scanline passes.


thanks in advance.


Sam Jorgensen

[DP]

are you using GI?

[sjorgens]

Yeah GI, very high settings

30 hsphere subdivs

60 interp samples.


what can I do to reduce this preparing scene step?

btw I am using the Very high settings simply because if I dont then all the small pieces wont cast shadows they look like they are hovering in space.

Any tips or tricks on how I could optimise would be great.

Thanks guys...


Sam

[DP]

have you got it to setup to show you the IRmap passes?

[sjorgens]

have you got it to setup to show you the IRmap passes?

yes,

but that doesn't make any difference if I turn it off.

What we need is some kind of read archive system like in Renderman where if the scene geometry isn't changing then it shouldn't have to be re-meshed every time you go to render.

Sam

[cpnichols]

The answer is very simple... When you "prepare scene" in scanline, it simply indexes the information of your scene. When you do it in Vray, or any other raytracing package, it loads the entire scene into memory so that it knows where things are when it bounces the rays around. A good example of this is if you use a max raytrace material in scanline, the moment the first object with raytracing appears, you see the "preparing raytracing" dialogue pop up. The bigger your scene the longer that takes.

Vray is a raytracer to the core, so that even with no reflections, no refractions, no GI or anythings, it will still raytrace the scene and load it in memory before starting to render.