Overbright material causes?

[paulison]

Hi,

Im wondering if someone can explain a couple more reasons for materials returning overbright values

I have a scene which ive added some trees and furniture to and converted all materials to standard vraymtl's. Now when I render this scene, I get a lot of overbright messages through the lightcache stages and IR map stage. When it gets to the IR map calculation the screen turns solid blue or solid red depending on if i use HSV colourmapping or linear exponential with more overbright materials. Many of these materials are from other scenes which all render correctly, some are new, but all are vraymats. The lightcache stage looks almost normal with the occasional blue/red dot mixed into the grain

I have converted all of the blinn mats to ward and this seems to be solving the problem (ill know when this render gets to this stage)

I have a small amount of displacement on a rug, and changed the colour output of a fabric from white to red (quite a big change)...could these be the cause?

i always seem to get these issues....argg!. I thought it was worth a mention though incase this is actually a bug that had slipped through

any help much appreciated

[paulison]

ok ....

blinn material for vraydisplacement objects is a no-no?

this is the second job i've done where changing the displacement material from blinn to ward has solved my blotching/ weird problems using 2d displacement. Anyone else noticed this?

[percydaman]

no, but be assured Im going to check it out.

[vlado]

blinn material for vraydisplacement objects is a no-no?

It should not be an issue, but if you have a test case that demonstrates this, you can send it to me at vlado@chaosgroup.com

Best regards,
Vlado

[paulison]

ive been adjusting this scene but now it renders out almost black. Before I inserted a bunch of objects (3DS trees) and FBX imports from Maya (interior objects) the scene rendered out fine, but now its totally stuffed.

Im guessing now ithat something i imported didnt have UVW mapping or the normals are screwed? maybee the scene is just corrupted.

is it ok if i email you the file vlado? 2.9mb zipped

ive really screwed the scene up and i'm very interested if you find out whats wrong with this one. Im guessing the mapping but cant find where the problem is coming from.

the lighting looks ok during lightcache but for IR mapping its almost black but I know my light setup works fine based on the previous project

[vlado]

The problem seems to come from the bitmap cropping bug in 3dsmax (see my post in the General section. If you are using 3dsmax 7, then I can send you a recompile of the bitmap texture that solves the problem. Otherwise, apply cropping to all your bitmaps.

Best regards,
Vlado

[paulison]

hi vlado, im using viz2005 but will go and crop all textures and see if this helps.

this is how the scene renders currently:



at the moment im stumped....the only real change i made to the scene was to import some objects and now almost every material in the scene returns an overbright colour

[paulison]

ive deleted all objects imported in the scene and it still renders out in flouro's.


the only other thing i can think of is that I tried to chamfer corners after converting the mesh's to editable poly's. Possibly i've created some crazy geometry...ahhh. Next im going to try delelting displacement and then all photometric lights. I've got to be getting close to finding it now

when I find this solution i'll definatly let you all know!

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EDIT: THE DISPLACEMENT MAP WAS THE CULPRIT!!!!!!

Maybee a list of do's and donts with the displacement map is an idea. For example, put a 1 pixel border around the map to avoid splaying at the edges, put the texture into the mat editor and make sure bitmap cropping is applied and also ensure uvw mapping is applied?

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EDIT2: Chamfering poly mesh caused huge problems (my geometry was messed up) which was causing this weird stuff