How to approach UV's for texturing a high-detail asset in substance painter?

[Jethro Au 0]

Hi everyone, just a quick question regarding UV's for substance painter. I am currently setting up a car for texturing in Substance Painter to be rendered in Vray for Maya. Essentially my question is how do you effectively prepare the UV's for a high-detail asset (movie quality)? Currently I have many UDIMs that cover different materials as I want ample space to texture all the objects. However, I understand that substance painter only allows you to paint in the 0-1 space. I assume I will have to break up the objects into groups and texture them individually (ie. import half of the metal objects and texture them and then do the next half and so forth) and have all my UVs in the 0-1 range. However, I feel like I could potentially waste a lot of time exporting and importing numerous objects/UVs for each material. I guess my underlying question is how do you figure out a good middle ground between using less UDIMs (and subsequently less imports/exports) and keeping it high quality?

Here are some images as reference.

my car https://imgur.com/Dj6VNdP

my UVs https://imgur.com/GU7a91Q

reference https://imgur.com/JD86oJf

[volker]

You do not need to break up the objects into groups and texture them individually, you can texture the entire car in a single Painter file and still use UDIMs. You can have a single OBJ file with UVs setup in tiles, just activate the 'Create a texture set per UDIM tile' checkbox when creating the project.

It all depends on how you define 'high quality', and how close the render camera will be. Star Wars-like camera flight through the profile of the tires? Given that you can export 8k textures for each UV tile you need to setup the tiles accordingly. Maybe e.g. put all tires into a single UV tile?

Give it a try, assign some materials, paint a couple of strokes. If you don't get enough resolution, edit the UVs and re-import the mesh. You will not lose any of your work (manual paint strokes will only be preserved in the correct location if you don't move the geometry).

[JabbaTheNut]

Jethro Au O,

While Substance Painter allows for a UDIM layout of your UVs, it does not allow painting across UDIMs.  This is relevant when trying to achieve "film" quality resolutions.  As an example, assume you have a basic hero character and that your camera will get close to the character's face, such that the eyes and nose will fill the screen.  Using a 2K pixel film screen width, the width of the character's face UVs would need to roughly span the full width of a UV tile for a 2K texture.  If the characters full body is to be UV'd at the same resolution, this would require that the body span many UDIMs.  If you needed an even higher resolution, or texel density, than the character would need to span even more UDIMs (effectively scaling up the UV's).  While Substance Painter would accept the several UDIMs of this scenario, it would not allow you to paint across them.  You would have to paint each individual UDIM of the body separately.  Imagine trying to paint details on the character's head or chest when it spans 4+ UDIMs and you have to paint each one separately.  Matching details across UDIM seams would be very tedious.  This is simply not feasible.

Until Substance Painter allows for painting across UDIMs, your UDIMs will need to represent discrete paintable units of your models (e.g., each object on its own UDIM tile, each material on its own UDIM tile, each unique part of your model on its own UDIM tile, etc.).  In this scenario, Substance Painter can be quite beneficial.