PDA

View Full Version : Mental Ray Texture Render Problem


melodico
05-25-2009, 09:57 PM
Hi. This is a WIP I'm working on. I did a test render to see if the textures are working. I'm having a problem, when I render with the maya software the texture looks normal but when I render with mental ray the texture gets distorted. Help please. Thanks in advance.

royter
05-26-2009, 06:22 PM
can u post your scene?

TheNeverman
05-26-2009, 09:15 PM
I'd guess it's a filtering issue...
What are your file node settings for the texture?

el diablo
05-26-2009, 09:38 PM
render them both as poly's and not subD. if they look the same as polys then it is a UV interpolation issue....el diablo

melodico
05-27-2009, 03:12 AM
Ok guys, here is a link to download the scene. I couldn't attach the file directly because of the file size limitations. Hope you find what the problem is. Thank you guys.

http://www.4shared.com/file/108034955/3a7f2cf6/PODScene.html

el diablo
05-27-2009, 06:49 PM
your problem is the way the UVs interpolate during the subdivision. The GL viewer in Maya can be decieving in telling you how the UV/map connection is. Especially on Maya subD shapes that will be rendered in MR. A quick fix for you is to convert your subD to a polygon
Tesellation Method = Uniform
Level = 2
DPF = 1

Now Convert this polygon back to a subD

This will acount for Mayas UV interpolation that would see in the GL Viewer and bake the UV interpolation in the mesh for MR. Now I know that you are looking at the mesh and saying this is to hi res and it is, but it will give you the results you need. FYI whenever you paint maps for shapes that will be subdivisionSurfaces always paint them at least 1 subdivision higher to accomodate the UVs interpolation. Then put those maps on the lowest level...el diablo

Ironhalo
05-27-2009, 08:17 PM
i've had the same issue in the past with poly shapes. normally i solve the problem by adding more edge loops to the model. is there a better way to address this? i assume the problem still lies with how the uvs are interpolated. i wish there was a better way to control that :shrug:

melodico
05-27-2009, 08:26 PM
Thank you man. That solved the problem.Every day we learn something new. Thanks.

el diablo
05-27-2009, 08:29 PM
i've had the same issue in the past with poly shapes. normally i solve the problem by adding more edge loops to the model. is there a better way to address this? i assume the problem still lies with how the uvs are interpolated. i wish there was a better way to control that :shrug:

If you render in MR it is BlackBox stuff so there is no way to control it. Also I dont see and UV interpolation options for subdAproximation. prMan has several. So the best way is to paint on iterations up and use the maps on iterations down....el diablo

Ironhalo
05-27-2009, 09:47 PM
hmm i think im missing something here, or its a different problem. im talking about a mesh that's polygons, and never had anything to do with subdivs. texture warping happens, especially along seams.

for example, create a poly cube and add a couple edge loops around the edges. apply a texture map and a subdiv approx and it'll warp along the edges.

i know there was a bug in the first release of 2008 that caused cracks along seams, i dont think this is the same issue.

el diablo
05-27-2009, 10:04 PM
you always need to put a bleed on your uv borders to remove cracks from mipmapping....el diablo

Ironhalo
05-27-2009, 11:15 PM
it really seems like an issue with how it handles uvs, and uv edges. i uploaded a scene as an example. masses of topology make it less apparent, but never seems to completely resolve it.

el diablo
05-27-2009, 11:37 PM
it is very important when a mesh is going to be a subD in MR how the UVs are laid out. Since your meshes are intended to be subD in MR but only polys in Maya the UV border is important. What you need to do for pCube2 is to insert an extra edgeLoop along pCube2.e[113] to stabalize the row that is stretching in. Weigh that edge toowrd the UV side that has no shoring and it will hold....el diablo

CGTalk Moderation
05-27-2009, 11:37 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.