"Allow negative colors" + UDIM flag

[VISUALMAN_TOKYO]

Hi there,

I am using a UDIM sequence for vector displacement, I added vray "allow negative colors" flag to file node, and when I set the "UV tiling mode" to UDIM, the VD is only outwards while is flat where should be inwards. So I am forced to concatenate all the textures via the default color (this works fine).
Is it a bug or am I missing something?

[tashko.zashev]

Hi,

This is a known issue which cannot be fixed. V-Ray can't figure out the correct displacement bounds for UDIM textures and assumes only black-to-white range.

[FSGFX]

cannot be fixed... ?
really`?

[tashko.zashev]

For the moment, unfortunately yes.
We will let you know if manage to find any workaround.

[FSGFX]

so for now the solution is to use ptex if i need vector dispmaps..?

[ivaylo.ivanov]

Doesn't manual displacement bounds work? Or the method described here?

http://docs.chaosgroup.com/display/V...and+TIFF+Files

[vlado]

Specifying the displacement bounds manually should work fine, as Ivaylo pointed.

Best regards,
Vlado

[VISUALMAN_TOKYO]

Thanks for your reply!

[Yannick]

Hi,
I am having the same issue with displacement maps from Zbrush. Any negative value are not displaced when using UDIM.
I try to add the attributes maxValue and minValue to the file node but that didn't change anything. DO I need to reoad the file or restart maya for the attribute to be read?

Thanks,

Yannick

[tashko.zashev]

Hello Yannick,
Are you using the Displacement bounds Min/Max values for this setup or EXR attributes ?
What is the exact Maya and V-Ray version ?
Can you post the Maya file here?

[Yannick]

Hello Yannick,
Are you using the Displacement bounds Min/Max values for this setup or EXR attributes ?
What is the exact Maya and V-Ray version ?
Can you post the Maya file here?

Hi Tashko,
after more investigating, it seems that we had a scale issue with the displacement maps.
So using normal displacement while setting the min/max bounds value, seems to work with UDIM.
I never had the problem before, i was trying to debug a colleague's scene.

On a side note, where do we stand with vector displacement from Zbrush?

Thanks,

Yannick

[tashko.zashev]

Hi Tashko,
after more investigating, it seems that we had a scale issue with the displacement maps.
So using normal displacement while setting the min/max bounds value, seems to work with UDIM.
I never had the problem before, i was trying to debug a colleague's scene.

I'm not sure what could be the problem in this case. If you manage to find something please share.

On a side note, where do we stand with vector displacement from Zbrush?

The Vlado's post below could be very useful if you are going to render vector maps generated by Z-brush.
http://forums.chaosgroup.com/showthr...546#post571546

[Yannick]

Tashko,
the initial problem wasn't been resolve with the min/max bounds values because the value in the displacement maps where too low.
The weird things was without UDIM, it worked fine, only when using UDIM, that the clipping occurred. We had to rexport the disp map from zbrush with the right scale and that solved it.

Regarding the vextor displacement, will the seam issue be fix int he future?

Thanks,

Yannick

[vlado]

Regarding the vextor displacement, will the seam issue be fix int he future?

Yes.

Best regards,
Vlado

[Morbid Angel]

Yes.

Best regards,
Vlado

Vlado is that the same seam issue I've reported before?