render grass | settings

[peterL]

Hello girls and boys,

I'm sitting here in front of a huge scene, about 1/4 is grass (geometry replicated).

How can I speed up render times?

first step in Modo for me would be to create a own shader for the grass material and set it to monte carlo ...

Does Vray recognize that anyhow or are there other options I can use, a setting that allows for the gras to be grainy (needs less time to render logically, and is not seen anyhow)?

glad for any hints!

[vladimir.nedev]

The Indirect Illum Type channel on a Shader item that you are referring to, where you can choose between None, Monte Carlo and Irradiance Caching, is not used by V-Ray for MODO.
Not sure if it would be a good idea to use it or not.
In V-Ray, you switch to Monte Carlo GI for a surface by going in the V-Ray Object Properties tab of the Shader item, and unchecking Use Irradiance Map.

You can also modify the Subdivs multiplier, which is again in the V-Ray Object Properties ( if you don't have a latest nightly build it will be called GI qual. multiplier I think ).
This is similar to using MODO's Shading Rate, although you use it in reverse, lower Subdivs multiplier leads to lower quality, but faster render time.
Try setting the Subdivs multiplier to 0.0 and see what happens.

Greetings,
Vladimir Nedev

[peterL]

Hello Vladimir,

I used your setup for a different material mask in my scene wich also could be rendered faster by 'brute force' settings. a wire mesh fence (basically a plane with an occlusion map and bump map on it). This one always takes a lot of time too in Irradiance map renders.

I placed the material mask above the main shader placed a new one in the mask above the material, as you do, enabled the v-ray options unticked irradiance map and 'tried' to give the GI quality mult. (as it is still called here) a value of 0, wich does not let me go beyond 0.01.

It is 95,5% faster to render the same Region;

With GI q.m. on 1 it is 0.56% faster;
on 0.2 it is 75% faster;
on 0.1 it is 85,34% faster;

kind Regards Peter

[vladimir.nedev]

wich does not let me go beyond 0.01.

I think I fixed the min value to be 0.0 as well.

It takes 62% longer to render the same Region;

With GI q.m. on 0.5 it is 2.24% faster;
on 0.2 it is 9.11% faster;
on 0.1 it is 3.28% faster;

I can't really tell you why that is without the scene, but even then it will be hard to tell.

Edit: What about the fur ? On my simple test, this setup worked pretty well I think.

Greetings,
Vladimir Nedev

[peterL]

damn you're too fast man ... just edited my last post

no, fur is not an option for me ... I want to have control over the geometry!

I want to add different types of leaves and flowers ...

[vladimir.nedev]

damn you're too fast man ... just edited my last post

no, fur is not an option for me ... I want to have control over the geometry!

I want to add different types of leaves and flowers ...

Sorry, I just tested it with fur and forgot you were using replicated geometry. Anyway, this doesn't matter. What matters is the detail that the geometry has.

I see in your edit that the results are as expected.

Greetings,
Vladimir Nedev