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View Full Version : The dilema of Ptex!!!


melviso
08-27-2011, 06:49 AM
I have been using ptex for sometime for my models with Mudbox but I had to go back to uvs cause of the following:

-I cannot reuse textures.e.g I want to use the textures of the right arm for the left arm thereby saving texture space.
-I want to put all the textures of lets say a 3d character,his hair clumps,belt,shoes,armours,weapons and kit in two texture files of 1280px.With uvs,I just unwarp and place them within the uv space and export snapshot to Photoshop.
-I can't move textures from one part of the model to another.Like a poster on a wall,maybe its too low.I want to take it higher.
-No lasso tool.
-If I am texturing hair clumps.I have to paint every clump of hair when I could easily reuse a texture map.Also,there are hidden parts of a model like inside the mouth or hair overlapping each other or folded part of a mesh.How do you paint those parts in 3d.This is when uv comes in,you paint your textures without moving 3d mesh around to get to the parts you can't paint.

-I have to admit painting without uvs is great but I am trying to understand how it saves texture file size as against one having control over number of maps for a model with uvs.Though uvmapping a complex environment is gonna be work.
Ptex has its advantages though.BTW,is it compatible with Maya mental ray and software renderer.I understand it works with the viewport renderer 2.0

Sandro
08-27-2011, 08:06 AM
I don't see ptex dilemma here, it's more 3d vs 2d painting dilemma, and not having photoshop-like tools in particular 3d painting app.

Also, uving is not that tedious nowadays with tons of scripts, apps and plugins to aid process, why skip it?

pior
08-27-2011, 02:39 PM
Regarding re-using parts of a texture : I would say that the best way to go around it is to make a 2d stamp of an existing area that you want to duplicate.

You can also start with ptex and reproject to a regular UV layout later on.

vargatom
08-27-2011, 07:10 PM
I think there are some render time considerations as well, as ptex was originally developed for movie productions at Disney. Maybe some easier memory management or such.
Also, movie VFX creatures need very very high texel density so it's pretty common to use dozens of 2K maps to get enough resolution. They achieve this by offsetting each UV island in the UV space beyond the [0,0] [1,1] area. Think about creatures like the dragon in the last Harry Potter movie - something with a huge surface area that needs to have enough texture res to work in close-ups of the head or other body parts. So they can't just unwrap it into a single map because no machine would be able to load that texture. But managing all those files for all layers can get problematic so probably that's why they decided for a completely new approach with ptex.

Now games have so far been limited by the amount of VRAM in consoles/PCs because everything had to fit in there. But if Carmack's virtual texturing approach becomes widespread than game assets might get to the point where even characters and vehicles can have practically unlimited resolution. Then ptex might start to become important for game asset creation too, even if it'd get unwrapped and reprojected into a texture atlas in the end.

Then again it's unlikely that the next generation of consoles would get that powerful, not to mention how much time and money it costs to build an asset like that dragon... But who knows, I don't think anyone expected the X360 in 2005 to eventually reach the level of utilization we see now in Rage and Battlefield 3.

vargatom
08-27-2011, 07:13 PM
Anyway, my point is that the reason Mudbox has ptex support is so that it can be used to paint displacement detail for movie VFX assets. But even there it's not a clear decision to use it or stick to UVs (which can be used for a lot of other stuff too).

oglu
08-28-2011, 04:13 AM
ptex is not built for game assets...
its for assets they need huge ressolution like in feature films...

its more flexible to work with uvs on eveything that fits onto one or two texture maps..

melviso
08-31-2011, 06:19 AM
I guess Ptex is for high resolution textures in movies and not for games besides Mudbox keeps crashing after some time,when I am painting in ptex format.

I will stick to uvs for now as I can determine what the size of my textures should be and what parts I want to reuse.Besides,its not compatible with Mental Ray.