Texture atlas texture creation confusion need some info (examples in post)

lockey1995

Hey, Was just wondering how are texture atlases generally constructed, I've been playing with trims etc and i now understand those but I'm doing some distant buildings in the background that really don't need a trim as i feel it's overkill and I'm trying to keep the materials down. The thing i needed clearing up is the creation of them are they.

1. unique uvs all packed into one and textured
2. Images put together in a texture in say photoshop and then the geo is unwrapped later the same as a trim?
3. Geo baked into a plane and then textured 

Or are all of  these  correct but depend on the situation I've just been trying to wrap my head around how these are created lol, i feel like I'm overthinking this as i end up doing but some clarification on direction would be great. I've put some examples of what I'm on about in the post.

Cheers

PolyHertz

Atlases are made from packing a series of smaller textures into a larger one. Their main purpose is to make dealing with many small textures easier for the artist, and to improve performance (loading one larger texture can be faster then loading many small ones). Textures that are packed together in an atlas should have a logical correlation (buildings, characters, etc.) that's based off when and where those textures would be loaded (you don't want to be loading an entire atlas just for one texture in it).

When making an atlas you want to consider how they would scale down for mip-maps (unless you're doing retro 3D of some sort that doesn't use them). To do this the individual textures should each be power of 2 resolution (128x128, 256x512, etc.), and you'll need to determine which method you want to use for padding;

A. Add padding directly into each texture you're packing (so add a few pixels to the border when authoring each individual texture)
B. Scale the texture inward by a few pixels and use the outer blank area for padding (this method should obviously be avoided if you're authoring textures per-pixel since the scaling will blur them).
C. Create / Edit the mip-maps by hand instead of relying on the game engines automatic solution.
D. Leave space in the atlas for padding to be placed around each texture. Color bleeding will occur with this method if your mip map resolution gets too low.

Also, the second example picture you posted was done by someone who was definitely more interested in saving triangles then texture memory, as that is one incredibly wasteful atlas.

Alex_J

Not overthinking - just that the order of operations matters.

If you look at a bunch of tools and try to guess what they do you'll come up with all sorts of crazy ideas.

If you start first by understanding a problem then you'll start to come up with tools needed to solve the problem all on your own. Then when you see the common tools others are using it will make sense fast.

This is why making student art in the context of an actual game is worthwhile, versus trying to make art in isolation and wonder if you are "doing it right."

polyhertz already answered I am just saying shit I wish I had understood when I started leearning 3d.

lockey1995

PolyHertz said:

Atlases are made from packing a series of smaller textures into a larger one. Their main purpose is to make dealing with many small textures easier for the artist, and to improve performance (loading one larger texture can be faster then loading many small ones). Textures that are packed together in an atlas should have a logical correlation (buildings, characters, etc.) that's based off when and where those textures would be loaded (you don't want to be loading an entire atlas just for one texture in it).

When making an atlas you want to consider how they would scale down for mip-maps (unless you're doing retro 3D of some sort that doesn't use them). To do this the individual textures should each be power of 2 resolution (128x128, 256x512, etc.), and you'll need to determine which method you want to use for padding;

A. Add padding directly into each texture you're packing (so add a few pixels to the border when authoring each individual texture)
B. Scale the texture inward by a few pixels and use the outer blank area for padding (this method should obviously be avoided if you're authoring textures per-pixel since the scaling will blur them).
C. Create / Edit the mip-maps by hand instead of relying on the game engines automatic solution.
D. Leave space in the atlas for padding to be placed around each texture. Color bleeding will occur with this method if your mip map resolution gets too low.

Also, the second example picture you posted was done by someone who was definitely more interested in saving triangles then texture memory, as that is one incredibly wasteful atlas.

So they are textures then not baked in or anything to make them, was thinking for a few outer buildings do you think it'd just be easier to do a unique uv with all the buildings packed in as texel density won't be an issue as they're just scenery assetts. 

lockey1995

Alex_J said:

Not overthinking - just that the order of operations matters.

If you look at a bunch of tools and try to guess what they do you'll come up with all sorts of crazy ideas.

If you start first by understanding a problem then you'll start to come up with tools needed to solve the problem all on your own. Then when you see the common tools others are using it will make sense fast.

This is why making student art in the context of an actual game is worthwhile, versus trying to make art in isolation and wonder if you are "doing it right."

polyhertz already answered I am just saying shit I wish I had understood when I started leearning 3d.

Yeah the issue with doing it in isolation and wondering if I'm doing it right is the story of my life lol really. I tend to get overwhelmed if i feel I'm doing it wrong. But i guess unless you're at a certain studio etc everyone does things differently it's hard to know how they acheived it.

I just didn't understand how it was made in the first place i:e put together in photoshop with a collage of images. But it looks like the geo is mapped to it which makes sense and clears up a few things, but i think I'll give it a miss and go unique instead with all the buildings i need.

 I'm only doing bits for games now I've mainly moved on to higher poly stuff and product viz style things. I just do bits every now and then always good to learn though

PolyHertz

Yea unlike trim sheets you're normally going to be creating the textures one at time before packing them into an atlas.
As for if you should use an atlas, that's up to you. If you think having them all on one sheet will make them easier to work with, and/or it'll help performance (something you'd have to find out through testing when making a game), then go for it.

lockey1995

PolyHertz said:

Yea unlike trim sheets you're normally going to be creating the textures one at time before packing them into an atlas.
As for if you should use an atlas, that's up to you. If you think having them all on one sheet will make them easier to work with, and/or it'll help performance (something you'd have to find out through testing when making a game), then go for it.

Cheers, yeah that clears up quite a bit there i now know how they generally go together now with creating them one by one etc. it's actually a mod for a game i'm doing the bits i do on are on Rfactor 2 and Assetto Corsa which has an incredibly outdated engine lol 

lockey1995

I just saw one of their textures it was front of buildings, back of buildings, windows, doors etc and just assumed it was thrown together in photoshop and the geo mapped over it in game. Now i know there's allot more to it in terms of planning etc

lockey1995

PolyHertz said:

Yea unlike trim sheets you're normally going to be creating the textures one at time before packing them into an atlas.
As for if you should use an atlas, that's up to you. If you think having them all on one sheet will make them easier to work with, and/or it'll help performance (something you'd have to find out through testing when making a game), then go for it.

I just went with a unique uv textured in substance in the end all 3 in one map