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HJ-panorama
02-12-2008, 03:55 PM
hello

This seems abnoraml to me..!!
i have a model with a quite normal texture on it... with clean spaced Uv's..

i do render with Mental ray ,it's fine till i apply an subdivision approximation on the object suddenly, at the edeges where the smoothing moslty occures ,the texture stretches like the attached images...

i really don't know what to do with this..
please help me out with this :sad:

joie
02-12-2008, 04:52 PM
I had the same issue..., it seems that approximation doesn't know how to handle UVs or something...

HJ-panorama
02-12-2008, 05:25 PM
even worse joie

because of this you can't use a Normal Map with a Displacement Map at once for a hard edged object ( which requires subdivision approxiamtion )

as far as you'r using a normal Map itself , it is o.k.. but considering Disp Map, the same mess ( normal Map acts like texture, the same issue) ...:sad:

another images of the issue!!

Ash-Man
02-12-2008, 07:24 PM
can one of you guys post a sample file

HJ-panorama
02-13-2008, 04:23 AM
ashman

hi

it is as simple as that... make a reqular polygon cube ...bevel it with segments=5 or whatever you like...
fix the broken Uv's and assign a texture ( not procedural, jpg is fine) to it's color...
then do a render with Mental ray...
then assign a mental ray subdi approximation to it.. with spatial, length 0.1 , etc..

do another render...
you 'll get this !

Ash-Man
02-13-2008, 01:06 PM
OK I get a diffrent thing


Not exact though,the edges seemed to be messed up

It might be related to the CCmesh (new approximation with mental ray in 2008)
however I think it's teh bevel rarther than anythign else

shoox
02-13-2008, 02:57 PM
I had the same issue..., i tried every thing . . :banghead:

HJ-panorama
02-13-2008, 03:07 PM
yes, CCmesh helped it out a little bit....

but as the image shows there is still stretching in some areas ... after applying ccmesh correction ...

what should be done to fix this?!!!

joie
02-13-2008, 04:58 PM
I think we CAN'T use subdivision approximation at all...

RingoStar
02-13-2008, 05:16 PM
Hi Guys, I found a solution. I guess you have been using Maya FileTex. MR messes up with the filtering. So if you set filtering (First Tab) to "none" in the file node it works.

Cheers,

Michael

Ironhalo
02-13-2008, 06:07 PM
Hi Guys, I found a solution. I guess you have been using Maya FileTex. MR messes up with the filtering. So if you set filtering (First Tab) to "none" in the file node it works.

Cheers,

Michael

correct me if im wrong, but if filtering is set to none (as opposed to mipmpap) cant you end up with rolling textures? i wonder if setting the filter to 0 would fix this...

HJ-panorama
02-13-2008, 07:56 PM
RingoStar

turning off the filter ( to none from whatever it is..) won't do much with this.. i think!

it gives fairly small additinal improvement at seams ( especially Normal Map seams) .

for this problem i believe there must be something better ...

HJ-panorama
02-14-2008, 08:56 AM
is there any chance to remove this curse.. !!!

RingoStar
02-14-2008, 09:23 AM
I know it sounds weird but when I switched from "quadratic" which is default to "off" my texture was ok. The stretching looked pretty much like the one in the pics posted before.
I checked again and it works for me. At least give it a try.
In theory it should only work on the edges or texture seams but maybe something else is happening during scene translation.

RingoStar
02-14-2008, 10:32 AM
The new problem for me is that the maya bump node has a built in filter as well which causes the same stretches. Even native bump_map_2 node from MR filters something. If you switch off filtering in the maya bump node bump mapping doesn't work at all and just creates strange patterns on the surface. Anybody found comments on this problem somewhere else ?

HJ-panorama
02-14-2008, 03:39 PM
I know it sounds weird but when I switched from "quadratic" which is default to "off" my texture was ok. The stretching looked pretty much like the one in the pics posted before.
I checked again and it works for me. At least give it a try.
In theory it should only work on the edges or texture seams but maybe something else is happening during scene translation.


at my end... i don't use bump maps at all, they'r useless , instead Normal Map does a fantastic job with Mental Ray

but you know, a normal map has its own filtering system alike textures so ... i turned it off and i was good at edges as i said, the stretching is the point to be solve in another way i think !

did you resolve it by simply turning the filtering mode off?
i didn't work for me..!!

RingoStar
02-15-2008, 10:09 AM
Ok. next try. The guys at lamrug.org posted this:

http://forum.lamrug.org/viewtopic.php?f=6&t=1352

I tried the patch on the approx node and this seems to fix the problem as it returns to an old version of subdivision algorithm.

Does anybody know what a ccmesh is ?

achoury
02-15-2008, 01:08 PM
hi
From gnomologie video tutorial (creating a normal map with Zbrush): show exactly the same problem!
here is the snap for the artifact generated by the normal map in zbrush
http://img81.imageshack.us/img81/5796/normalartifactoq3.jpg

the solution is to increase the rasyscaline max distance before generating the normal map
here is the sanp showing the correction:
http://img227.imageshack.us/img227/787/normalfixedgi4.jpg

hope this can help you
Rachid

HJ-panorama
02-15-2008, 02:13 PM
very good start ...

yes, rolling back to old subdivion procedur by the Mel command seems to fix the seam's issue a lot..

but there is some sort of stretching yet..
guys, what can we do with the old texture stretching issue at edges?!!

ps: i do take my Normal Map in Zbrush at the highest Max Raytrace Distance...but it fixes the clipping issues of Normal Map for shapes with highly defomed topology in comparison to base mesh..

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