UV Pass Maya - Nuke Stmap Remapping

[Nicolas Bulchak]

Has anyone used this workflow.

UV pass Vray for Maya

Nuke StMap merged over original render

 I have an object that I want to remap so that I can output several versions with new patterns.

The issue I am having is when I remap, I don't get the same result with the lighting on the surface as I would rendering the map on the surface directly

Any help would be appreciated

[matt estela]

Is your uv pass in full float? I found the default of half float caused precision errors for the stmap node, things would be misaligned by a tiny amount at best, or be substantially aliased and offset at worst for really extreme cases, eg camera really close to a surface, with part of the surface receding rapidly to the horizon.

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[Nicolas Bulchak]

Yeah, I am using 32bit. I think I may have to do an RGB rebuild and place that on top of my stmap in order to make it match the original. 

I really wish there was a tutorial out there following this procedure

[Ryan O'Phelan]

Render your UVs with no filtering or aliasing. 32bit helps. 

In Nuke, you can use a blur (or bilateral blur) to smooth out any troubles.

You can directly connect a sampler info UV to your pass, but I like to connect it to the color offset of a black ramp. 

Obviously, motion blur, DOF, etc. will f this up, so do the stmap before. 

Good luck,

Ryan

[Ryan O'Phelan]

I meant you can blur the UV pass in nuke, if you didn't follow. 

[Nicolas Bulchak]

Thanks! This helped a ton! The edges still look a little different then the target image, but much much closer. Im gona have to do a hi res test to see how noticeable the difference is

[Pierre Jasmin]

On 5/22/2014 8:49 AM, Nicolas Bulchak wrote:

Thanks! This helped a ton! The edges still look a little different then the target image, but much much closer. Im gona have to do a hi res test to see how noticeable the difference is

FYI: In RE:Map we have a UV edge discontinuity slider for that - this + alpha channel in UV usually makes clean edges

Just additional bit of UV map info, as we regularly have support issues caused by export settings not matching render wise expectations for this sort of things
For example in Max 2014, to output 32b EXR for these additional channels, one has to use the V-ray Raw image option instead of the Max Output module - otherwise the image is 8 bit in a 32bit body
We had this week someone trying to render 16bit TIFF in Maya but the output was actually 8 bit TIFF...

For sanity check one can use our plugin RE:Map UV with mode Check UVs (even if in demo mode)
This will show as white dots where you have duplicated UVs (a neighbor the same UV as this pixel) which will cause blockiness (same UV value)

Pierre
www.revisionfx.com

[Ryan O'Phelan]

I've used this for screen replacement,  and found that If I just rendered the screen without the bezel,  and mask it later,  it would turn out much better. 

R