UV transfer stops working properly at a certain polygon density

[acey195]

Hi,

I have a problem with the attrib transfer SOP.

when trying to transfer vertex UVs it seems to work till a certain resolution.

the object I transfer the UVs from stays the same, the object I transfer the uvs to stay the same.

It looks like the UVs with the closest positions snap, so there is a UV distortion pattern,

which matches the the geometry of the UVsource, generating a grid-like distortion.

I have tried:

-ray Sop

-subdividing the UV source (makes it even worse)

-applying it to a poly reduced version, works for the first part, but when applied to the high resolution mesh, I get the same problem

-scaling the object up and down

-using point UVs (creates a whole range of other problems)

relaxing the UVs reduces the problem slightly,

but at even higher resolutions it does also not help anymore.

http://forums.odforc..._hl__+uv +relax

Any thoughts?

Edit:

I have again looked at the ray SOP, results are looking good so far, as well as being slightly faster.

It seems that at a higher resolution Houdini also has difficulties with displaying texture maps correctly (uv map texture)

but when rendered, it looked fine.

Still need to complete the rest of the render to confirm everything is working as intended.

Edited December 11, 2012 by acey195

[sanostol]

Can You provide a example file for us?

[acey195]

I will be uploading the documentation of my current project soon (coming Friday/Saturday)

At that point I can create some examples if they are still needed.

[acey195]

The project I needed it for:

http://forums.odforce.net/index.php?/topic/16730-procedurally-generated-planets-for-usage-in-video-games/

I still intend to improve the UVs from where I am now, but at least they are better than in the first post.

[fxrod]

I have confirmed the UV discrepancy between the viewport and the render. This bug was reported to Derrick Moser from Side FX (in person. ) It has caused heartache. Lots of heartache, since you can't trust the viewport when it comes to texture mapping.

One thing... If you can, make sure you work with vertex uvs and not point uvs. This will prevent uv co-ords from stretching across boundaries. You can then use the Vertex SOP to transfer your UVs.

[acey195]

Thanks

I do work with vertex UVs . Vertex Uvs can be transfered with the attrib transfer sop as well.

Sometimes, when you do not have many seams point uvs can be faster though.