Hair and fur (grass) material problem in mental ray.

[Christ1982]

Hi,

I know there are many threads on here dealing with the hair and fur modifier being used to create grass, but from what i can tell nothing has come up dealing with this problem!

 

I have finally managed to get the grass to the correct length, not quite the correct density, but i know how to work on that, but the grass is not coming out the colour that i am selecting in the modifier...

 

Obviously i want it to be green and it keeps coming out as nightmare black grass!!

 

Anyone got any ideas?

 

[ATTACH=CONFIG]38466[/ATTACH]

[Christ1982]

as a follow up i have read various other forums/pages/posts that say that the problem could be with lighting or occlusion...

 

attached is an image of what i have at the moment and the settings i am using in the material parameters...if anyone has any inklings at all what they think the problem is a push in the right direction would be greatly appreciated!!

 

Chris.[ATTACH=CONFIG]38468[/ATTACH][ATTACH=CONFIG]38469[/ATTACH]

[Matt McDonald]

For what its worth, I think a lot of people are ditching the hair and fur for grass method because its just too troublesome for questionable results. Search around for proxy grass tutorials and I think you'll be end up with a workflow that is a little easier to adjust and looks great

[jinsley]

you can check out this thread... I start out with pflow, but near the end I start working with the hair and fur modifier...

 

http://forums.cgarchitect.com/37505-grass-test-using-particle-flow-mr.html

[jinsley]

sorry... didn't read that right. Matt is right, start taking a look at proxies... I only use the hair and fur to make my proxies...

[Christ1982]

Cheers for the advice guys, I will look into using proxies. One thing that I have struggled with is that all tutorials seem to place grass on either nice flat planes (built in 3ds) or slightly undulating planes (again, built in 3ds). I build my models in Microstation V8i amd then import them as dxf's into 3ds. Will the proxy method still work in this case?

 

Thanks again,

 

Chris.

[Kurt]

Why don't you just render the grass in Microstation using the Luxology engine?

 

fur/grass with microstation

Edited August 26, 2010 by Kurt

[jinsley]

Why don't you just render the grass in Microstation using the Luxology engine?

 

fur/grass with microstation

 

how large of a patch could you create with that Kurt? The grass looks really good!

[Crazy Homeless Guy]

I have had this happen before. I think it might have something to do with how the hair geometry is being processed. Try mr Prim, and if that doesn't work, try buffer.

 

Like I said though, I only think this may be a solution.

[Kurt]

how large of a patch could you create with that Kurt? The grass looks really good!

You can enable adaptive sampling, this will reduce the amount of fur based on the distance from the camera. Then you should be able to render almost any size.

 

grass covered island

[dande]

First of all I would bring the model in from MicroStation as a DWG. Because using DXF your more likely to have problems. DXF is an old format and MicroStations DWG converter is much better.

 

You won't have any problem with proxies once the grass blades are 3DS Max objects. Then proxy the grass blades. You can use a script to scatter the proxies. Have a look at Jeff Pattons tutorial on the http://www.mrmaterials.com

 

http://www.mrmaterials.com/jeffs-blog/101-mrproxy-grass.html