Help! Radiosity screwing up my grass...

[Ken Walton]

First - forgive the models in these shots - they're under heavy construction. I can't seem to control the radiosity in max on these exterior scenes - I just don't know how. I can get the drab scenes from the tutorials to come out great but when I try it on my scenes with grass the greens end up almost flourescent. What's up?

 

Here's the site using the ring technique with no GI or radiosity.

 

http://www.cgarchitect.com/forum/filepush.asp?file=site_ring.jpg

 

And here are my results with radiosity. The settings are ridiculously low in this shot, but no matter what quality I use, I still get the grass and color problem (the color of the buildings in this shot IS different from the first and almost right). What's happening to my lawn? This is the "thick grass" from the architectural material library.

 

http://www.cgarchitect.com/forum/filepush.asp?file=colorfuct.jpg

 

Any advice might save my life.

 

Thanks

Ken

[Brian Cassil]

It's the exposure control that's screwing things up. I'm not really sure what the solution is though. It's one of the reasons I never use radiosity.

 

edit: I just remembered the way your supposed to deal with these situations is to reduce the rgb level in the output section of the diffuse bitmap parameters in your grass material. It's a kind of a pain I think because your bassically reduced to trial and error in making it look right. Your material editor may display the material as almost black before it looks good in your scene.

 

[ January 28, 2004, 11:38 AM: Message edited by: Brian Cassil ]

[Ken Walton]

SWEEEEEEET!

 

Awesome, man - this seems to be working wonders so far.

[Alex Ryan Rubio]

you can try setting your exposure controls to logarithmic and set the physical scale to the same value as the brightest light in your scene. try playing around with the brightness and contrast multipliers. regarding the rather rough surfaces, apply an advanced lighting override material over your map. keep the old map and reduce the bump scale to something like 0.10. this will result in smoother surface shadows. hope this helps.

[William Alexander]

Try adjusting the map output curves or rgd ... controls in the output rollout. Get the radiosity looking good overall, adjust the outputs, using exisitng radiosity, for speed. Get it the grass material close, new radiosity, render and adjust.

 

You may also try using your grass map in the diffuse levels slot and or diffuse roughness, if using oren nayer blinn.

 

I never get good grass from most maps, I find these solutions work pretty well.

 

brgds

WDA

[kingeldar]

well i have a sort a solution consiting to add an intensity (architectural) usin same bitmap then find good value (around 60 _80 in my case)

but i'mnot sure this will always work