Mudbox -> Vray uv issues, ptex?

[ndeboar]

Hey,

I followed the vector displacment tutorial, and although the displacment looks great, i'm getting horrible uv seams. I've tried smoothing/not smoothing uvs, and not getting any love.

I've heard PTEX is the answer, could someone give a clear tutorial on exporting ptex displacment maps to vray for maya? All my tests have failed so far.

Cheers,

Nick

[ndeboar]

Sorry to bump this, but this could potentially be a bit of a deal breaker on the project im working on. I'm happy to use just normal displacment maps, as long as i can get rid of the uv seams. A good ptex tutorial would be a life saver
Edit:
Got ptex working! When importing the obj, click "single object", multiple object borks ptex.

What I can't get right now is the displacment level. Using vector displacment, the scale looks perfect, but that doesnt seem to work with ptex (not for me at least), and standard displacment maps i always have to put in arbitary displacment amounts, which i rather not do. How do i match the displacment scale to mudbox perfectly?

Edit:
Is it just me, or does turning on "2d Displacment" turn of subdisions? It seems to loose all smoothing? If im using PTEX, I can't smooth the model becouse it'll mess up the topology.

[Morbid Angel]

I didn't work with ptex or with vectors before, and really never had success with either. For the displacement, you should just bake out a 32 bit rgb exr, which will contain the proper values for your displacement without the need to enter the offset or eyeball anything, you would just set the displacement value to 1 and thats it. You would need to enable "allow negative colors" in the file node, as well as in the displacement control set the bounds to be manual and put them in range of your displacement something like -10/10 or whatever the highest and lowest displacement value in your map is.

[hellobard]

hey,
ptex really is the answer vector displacement doesnt work just yet, but standard displacement with ptex does. just follow my tutorial here:
http://blog.hellobard.com/2011/10/05...-displacement/

fire away if you have any questions. remember to prepare your model with ptex only after all of your modelling at the highest subdivision is done.

oh and just turn on subdivisions for your model within v-ray to subdivide it, as you say, you can't use maya mesh smooth, it'll send the ptex coordinates off.

[vlado]

I'm happy to use just normal displacment maps, as long as i can get rid of the uv seams.

Unforutnately for the moment they will always be there. It would be best to put them in a place where they won't be visible.

What I can't get right now is the displacment level.

From what I remember it should be 1.0, since PTex is a floating point format and displacement values are stored directly. You may have to adjust the min/max displacement levels, as V-Ray has no way to find them out in advance.

Is it just me, or does turning on "2d Displacment" turn of subdisions? It seems to loose all smoothing? If im using PTEX, I can't smooth the model becouse it'll mess up the topology.

For PTex files, either use V-Ray normal 3d displacement or V-Ray subdivision surfaces. Smoothing must be done by the renderer so you can't use the regular Maya mesh smoothing.

A good ptex tutorial would be a life saver.

Yep, working on one.

Best regards,
Vlado

[RobPhoboS]

hey,
ptex really is the answer vector displacement doesnt work just yet, but standard displacement with ptex does. just follow my tutorial here:
http://blog.hellobard.com/2011/10/05...-displacement/

Thanks for your link, much appreciated

[ndeboar]

For PTex files, either use V-Ray normal 3d displacement or V-Ray subdivision surfaces. Smoothing must be done by the renderer so you can't use the regular Maya mesh smoothing.

But, normal displacment clamps between 0-1, so I can't use the 32 bit displacments?

[Morbid Angel]

But, normal displacment clamps between 0-1, so I can't use the 32 bit displacments?

thats why you have to use manual bounds in the displacement control.

[ndeboar]

thats why you have to use manual bounds in the displacement control.

Just to confirm though, i would have to use displacments that are clamped between 0-1, eg 16bit?

[stezza]

Can anyone supply a very simple working maya scene file with ptex file, I just cant get this ptex working at all. I have followed the tut but to no avail.
Thanks for any help.

ok sorted, followed vlado's tut which helped get the displacement result needed.
http://www.spot3d.com/vray/help/maya...splacement.htm

s

[jreynolds]

Here is a great tip on UV seams and one fundamental concern to be aware of when dealing with Ptex

http://polygonspixelsandpaint.tumblr...gged/texturing

[Morbid Angel]

I agree with that tutorial but I must point out that according to his findings we should have always had uv edge problems with displacements but we do not. In fact I just did a test where I have organic shaped uv's and at a very closeup I could see a seam but it was very minor and I think that it is not a very good workflow to generate square edge uv's, it will be impossible to paint textures in photoshop sanely over those uv shells.