Texturing a sphere : a useless method ?

Lord Fryingpan

I recently had an idea, but I'm not sure it's very usefull or even clever.

Here is the deal : when you texture sphere-like objects, there is a large loss of texture space due to polar tris, and distorsion. So I thought : why not model a sphere from a box, and make each side of the box cover the entire texture space. The texture would reeat six time on the sphere, but there would be less deformation and much better resolution for the texture.




While allowing a texture to tile on a flat surface is no problem, texturing a cube began to be mind boggling... It cobe posible to make sure each side of the textue would tile to with the other three, but I wasn't quite sure the result would have been worth it, so I looked for a way to make each side to tile with only one other side



Solution was the following : side A would tile with B, and C would tile with D reversed. Once smoothed, the cube turns into a sphere, and the texture tiles just fine.

Problem now : I'm pretty sure someone has thought of this before me, and I'm pretty sure this is totally useless.

Any thought ?

Eric Chadwick

Kind of hard to follow your ABCD notation. It looks like you have 5 unique textures in the last example, is this correct? If they're unique then you're not really tiling.

One solution to this is to mirror-tile a single texture. But you still get the butterfly rorshach effect along the edges. And the artifacts are not really worth the savings in texture space, unless you're working with a very clean texture pattern.
What's an 8-sided tiled texture ?

Some methods for UVing spheres here.
http://wiki.polycount.com/TextureCoordinates

Lord Fryingpan

Eric Chadwick wrote: »

Kind of hard to follow your ABCD notation. It looks like you have 5 unique textures in the last example, is this correct? If they're unique then you're not really tiling.

Ah, I didn't manage to make myself clear. There is only one texture, with four sides : ABCD, clockwise. It can be either used as is, or flipped, then the order of the sides is DCBA.

On my second picture, there are three sides used in a normal way, and tree sides used flipped. A connects with B, and C connects with D flipped. Of course, it also means A flipped connects with D flipped, and C flipped conects with D

Eric Chadwick

Have you tried this with a photosource texture? Curious how it looks.

Mark Dygert

That seems like a lot of work to generate the texture, but I think it could work pretty well if automated like for brick patterns or floor tiles ect... There might be a way to use a procedural material generator like filterforge to handle the tiling?

For when you need 100% unique you can do a tennis ball unwrap, if you are careful with the edges you can stack the UV shells. You can pack 2-4 spheres on a square sheet depending on what method you do, which comes in handy if you are creating rocks. Quadspheres also work a lot better in sculpting apps.


Taken from here: http://www.polycount.com/forum/showthread.php?p=1312335#post1312335

Lord Fryingpan

> Eric Chadwick

Here you are (just a quickie) :



> Mark Dygert

Thanks for the tip, it seems indeed it's the modes efficient way to proceed.

Angry Beaver

I made a tiling texture like this for use on rock faces, it's not just for sphere's as it can texture corners between extrudes no problem if you line it up. Getting the tiling down is the hardest part.

You need a right angle triangle cut out of your texture like this

[COLOR="Orange"][COLOR="Red"]/[/COLOR]|
[COLOR="Yellow"]\[/COLOR]|[/COLOR]

Then you need to arrange it in a star shape

[COLOR="Orange"][COLOR="Red"]/[/COLOR]|[COLOR="yellow"]\[/COLOR]
[COLOR="yellow"]/[/COLOR]_\|/_[COLOR="red"]\[/COLOR]
[COLOR="red"]\[/COLOR] /|\ [COLOR="yellow"]/[/COLOR]
  [COLOR="yellow"]\[/COLOR]|[COLOR="red"]/[/COLOR][/COLOR]

You then keep as much as possible giving you a square shape and edges that always tile with each other. The middle is obviously a mess so you clone-stamp or your weapon of choice in the middle to get the seams gone.

Actually did a quick break down from my psd file for anyone else wanting to try
I. Source
II. Make a Triangle big enough for your source
III. You'll be aranging them like this once you cut them out
IV. Use this traingle to cut out a SINGLE piece you duplicate
V. Use the original image to paint over the middle so the edges disapear
Final. contrast and extra detials

Lord Fryingpan

Intesting technique, thanks for sharing