Non-power-of-two texture atlas

Unity Engine
1

I’m creating a texture atlas. Right now it is 4096x4096. I don’t need all of the space, so I could adjust the entire atlas to be maybe 3100x3100, and re-organize the UVs. But it there any value in doing that? Usually the texture atlases I see are always a power-of two. So if it was 3100x3100, it would be “upscaled” to 4096x4096.
What is a common approach in this situation:
Leave it the native PNG as 4096x4096?
Convert it to the smallest size of 3100x3100, and choose POT in the import settings?

This is roughly what it currently looks like:

2865797--209880--atlasUVs.png
2865797--209880--atlasUVs.png612×632 21.6 KB

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2

NPOT textures get padded to POT internally anyway as far as I know, and there may be some performance drop especially on older GPUs.

–Eric

1 Like
3

Ok. So I guess I should leave it as-is or go to 2048. It sounds like an atlas of 3100x3100 is useless.

4

For me. I will rearrange those UV nicely. (Occupy 90%+ space) and make it as 2048 texture.

1 Like
5

In Unity, I tried setting the max size to 2048, compressed. The diffuse texture was reduced from 21Mb to 5Mb. There really is no noticeable loss in visual quality in the player. Is this fine to just have Unity convert it to a 2048 since there is no noticeable loss in quality?

6

Technically there’s some minor quality loss there since reduced from bigger to smaller size.
You will realize it if your draw something in very details like ornament architecture.
You can let Unity compress for you into power of 2 for all textures but I’m not suggest that.
Reduce from power of 2 to another power of 2 is always better than reduce from other sizes.:slight_smile:

7

Concur with Akira.
Looks like that uv layout could be reorganized to fit pot 1024x2048 or 2048x4096 depending upon your desired resolution.