Modular Level Creation, Tileable Textures, No Padding, and Seams. Help.

Using- Maya, Photoshop, Unity

I'm in the process of studying more refined workflows in environment creation. I wanted to try the "Make Texture Sheet First" then model/UV according to that.

In the past, I've seen texture sheets in which all of the textures are butted right next to one another with no padding. I wanted to try the same thing.


Here is a screenshot of my texture sheet in Photoshop. I have a 16x16 grid in keeping with the power of 2.




And here is a sample wall section UV placement in Maya using the same 16x16 grid layout.




This is the end result. Using a 16x16 grid with strict snapping both in PS and Maya, I'm still getting seams.




Here I have turned off Mip Mapping and changed the Filter type to Point. Still getting Seams.


Still Not Much Better.



I'm really trying to get this No Padding Atlas Workflow to work. So adding UV edge padding would undermine my intent.

My colleges have suggested the same setting changes as well. They are stumped on this as much as I am.

I've made several environments with padding on my UV islands, but I just haven't come across that secret sauce to this type of texture layout.

I'm thinking a NO padding texture layout is a old texturing technique used in Unreal where there is no real measurement. Only Units. I'm thinking its just not as simple as using a power of 2 grid in my UV layout when using Unity.

Can someone point me in the right direction for understanding this? I've been searching for half an hour.

 

I spent a lot of time with the Unreal Engine (from 1.0 on) and always remember issues if you didn't use padding. The old versions of the Source Engine did some automatic packing for BSP and had a shader trick to clamp the texture mid-UV to prevent seams. For current gen Source I believe they just add padding or don't bother with the atlas as no padding causes problems for anisotropic filtering.

Now as for why you're seeing seems even without mipmaps and with point filtering, it's probably because floats aren't perfect. There's a little bit of slop in float values so your perfectly aligned UV might be getting into Unity as a tiny fraction off one direction or the other.

 

Mips and bilinear sampling would cause seams, but you'd still want those, no? I think there is a method to have bilinear sampling but clamp at a given edge. I think i saw that feature once.
Otherwise, as bgolus said, probably caused by float precision of the UV's.
I think UV's in Unity are compressed by default, which is set in "Mesh Compression" in the model settings. v5.2 has better options for this, try setting mesh compression to off and see if it helps.