Best way to prep a Texture for a Sphere?

Probably been asked before but.. does anybody have any pointers on how to prepararolorize a texture for use on a sphere iusing PS?

Mainly looking for nice even repeats of patterns without the distortion typically experienced when applying a pattern to those shapes..


I appreciate any insight you can give me....


Thanks

It depends what you mean by "nice even repeats". There are lots and lots of ways to wrap a 2D image around a 3D sphere. There's no universal answer. What exactly are you trying to do?

I've never had a pattern complex enough to worry about this one, but here's a thought you could try.

1. Make a sphere and texture it the way you want using a more capable 3D application like LightWave 3D.

2. Unwrap the sphere texture. Most of the 3D programs let you do this, or have plugins that will flatten and export a texture.

3. In Photoshop, do the usual stuff to the flattened image. Reduce the size/aspect ratio to import cleanly into SL, etc.

4. Upload and apply to your sphere. If SL wraps it the same way the unwrapper program thinks, it should look like the original.

/me crosses her fingers and wishes you luck

Lindal, just so you know, there's one potential problem with the method you described. Not every 3D modeling program wraps spheres the same way by default. A particular trouble spot can be the poles. Some will use quads for the top and bottom rows of faces, others will use tris. Of the ones that use quads, different programs will handle the collapsing at the very top and bottom in different ways. And of the ones that use tris, some will put the apexes at the left, some will put them at the right, and still others (like Maya) will put them in the center.

And then of course there are some programs that use cubical mapping for spheres, rather than more traditional globe type mapping. These can be a nightmare to work with for SL purposes.


In order for your method to work, you need to be sure your 3D app is UV'ing the spheres exactly the same way SL does it. That means use tris (or quads that collapse to tris) for the top and bottom rows, and have their apexes be on the left for the top row, and on the right for the bottom row.


ETA: Here's 24x24 quad test pattern you can apply to a sphere in SL, to see where every polygon is.



Once you've applied it, notice how the quads above the equator pinch toward the left, and the ones below pinch toward the right, the further from the equator you get. This is because the two tris that make up each quad have their hypotenuse edges running from the top left corner of the quad to the lower right corner, as indicated by the gray lines that diagonally bisect the quads in the texture.

Chosen, have you ever read Kleinzeit by Russell Hoban? If you haven't you may enjoy it, apologizes for going off on a tangent, I blame this post for reading the forums after a few hours sleep at 6am in the morning.

I am looking to compensate for the pinching.

It looks like PS does not really have the tools to do that though from what I am gathering..

thanks

No, I haven't, but I just read about it on Wikipedia. If the description there is accurate, it sounds like a great read. Thanks for the suggestion. I'll see if I can hunt down a copy. It seems it's out of print in the US.





There are all kinds of ways to proceed, again depending on what you're trying to do. Compensating for the pinching is a given. You'll have to do that, no matter what. I was hoping for a more specific answer. Here are a couple of examples:

1. If you're just working with a fairly uniform pattern, for which nobody would notice if a little bit of it gets cut out here and there, then the polar coordinates filter could do nicely for you. Note, it only deals with one pole at a time, so you'll probably want to chop your texture in half, and apply the filter twice.

2. If you have Photoshop CS4 Extended, then all you'd need to do would be import a sphere, and paint directly on it. You'd just need to make sure it's correctly UV mapped first, which is what I was getting at in my previous post.

that was it.. example roof tile for dome roofs and similar dome shaped surfaces. I missed the one pole at a time. I will look at that filter again more carefully.

Again thanks