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UV’d sphere help
Posted: 09 December 2013 10:18 PM   [ Ignore ]
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Hi,

Need either a mapped sphere that will allow for straight around symmetrical and blended mapping (like applying a cloud map) or instruction on how to do this correctly.  I’ve spent way to much time trying to figure this out.  I’ve tried a premade sphere from DAZ Studio and one from ZBrush but when I apply a map to it it’s all over the place and stretched out.  This will not due.  I’m surprised someone hasn’t come up with an alternative way to UV map something like a sphere to do this rather than relying on making maps in Photoshop.  Should be easy but it’s not and I’m at my wits end. 

Thanks for the help

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Posted: 09 December 2013 10:27 PM   [ Ignore ]   [ # 1 ]
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Like this? The uv map is on the right. This was done in Hexagon.

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Posted: 09 December 2013 10:35 PM   [ Ignore ]   [ # 2 ]
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I found this tut for blender that uses follow active quads technique to achieve a result similar to above.
http://blender.stackexchange.com/questions/3315/how-to-get-perfect-uv-sphere-mercator-projection

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Posted: 09 December 2013 10:47 PM   [ Ignore ]   [ # 3 ]
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Yes, I was able to achieve that in my UV mapping program but there is a very noticeable seam on one side of the sphere and that’s what’s frustrating me.  I don’t know how to match vertice by vertice and I know there is a way to do that because folks that take the time to match up older models UV’s to newer models to share texture maps between them know how to do that and I know it will be tedious but nothing worse that wasting an entire day like I did today.

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Posted: 09 December 2013 10:58 PM   [ Ignore ]   [ # 4 ]
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Wolf, Ram, and Hart, I am an admirer of yours, and will try my best to help you.

But you are speaking with such a thick “artist” accent that I am having trouble understanding what you mean by “straight around symmetrical and blended mapping”. I, in return, may be speaking too much “math” for you. Let’s see if we can converge.

I’m also wondering if you’re using “UV Map” when you mean “texture map”, because you mention PhotoShop and UV maps, but UV maps aren’t a PhotoShop capability. The texture map is the flat image (JPEG, PNG, TIFF, HDRI, etc) that gets wrapped around an object, the UV map is the table that translates the 3D coordinates of the object to the 2D coordinates of said picture. A program called an “unwrapper” tears apart the 3D mesh and creates UV map. For a sphere, you don’t need a sophisticated unwrapper, the cylindrical or cube unwrappers built into the free “UV Mapper” program can do what you want (it sounds paradoxical, but avoid UV Mapper’s “spherical” mapping. That actually is a pseudosinusoidal “orange peel” map that is a fracking pain to heal the seams). Just make sure your sphere is a relatively high polygon object, or you’ll get even more distortion and difficulty healing the seams.

What you described sounds like a major problem with seam healing. Can you show us the problem? Is it alignment, or is it brightness or color not matching.

There are many ways to UV map a sphere. Do you want to be able to “paste” a flat image onto the texture map and have it wrap around the sphere in a civilized fashion? Are you hand painting? The most common mapping for things like sky domes is “cylindrical projection” (which is also available on UV Mapper, so it’s handy). A cylindrical projection only has one seam (very easy to deal with, but if you don’t, look out, because it’s major) but is only reasonably distortion-free near the horizon. Distortion increases towards the top (zenith) and bottom (nadir) of the sphere, and at the zenith or nadir themselves, distortion is infinite, so they are very difficult to hand edit. They are a piece of cake to piece together out of multiple overlapping reasonably flat (conventional) pictures of a sky, if you use a panoramic stitching program. The one I normally use for this stuff is called hugin, and it’s a wrapper around a bunch of good programs (“enblend” and “enfuse” that blend pieces of sky or horizon without ugly seams, “panorama tools” to do the actual warping, “SIFT” and other automatic alignment programs).

Hugin supports every major mapping, but you want to use cylindrical or cube for this, matching whichever you chose in uv mapper when you unwrapped the sphere. Cube is a little easier to hand paint than cylindrical, but it’s also more likely to show visible seams. Everything wrong with the Worldbase product stems from a foolish choice of a cube map over cylindrical.

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Posted: 09 December 2013 11:14 PM   [ Ignore ]   [ # 5 ]
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It would depend greatly on what you’re trying to make. A basketball? A planet?
Let’s take for example the planet Earth. You can find some nice free texture maps here:
http://oera.net/How2/TextureMaps2.htm
You’ll notice the textures are stretched at the poles. They also are seamless at the left and right edges. Any spherical object is going to need a uv map created with this type of texture orientation in mind in order to map without distortion.

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Posted: 09 December 2013 11:38 PM   [ Ignore ]   [ # 6 ]
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You can create a primitive sphere in DS and browse to load it in as a diffuse texture onto the surface and see that it maps well as is.
So it’s really about the map. It has to be pre-stretched at the poles and seamless on the ends. So to make one from scratch, you will probably need a paint program of some kind, whether you use a uv texture map or not.

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Posted: 09 December 2013 11:46 PM   [ Ignore ]   [ # 7 ]
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Hi,

No, I’m looking for a way to UV map a sphere straight around so I can simply apply a texture map that follows it all the way round and blends at the seams.  I’ve tried Spherical and Cylindrical as well as trying out the default ZBrush mapping for the sphere. And while the ZBrush mapping is close it’s a bit chaotic in how it blends around the sphere.

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Posted: 10 December 2013 12:11 AM   [ Ignore ]   [ # 8 ]
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Sorry then Wolfie, that’s the only experience I have with mapping a sphere. Good luck, I hope you find a solution.

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Posted: 10 December 2013 12:28 AM   [ Ignore ]   [ # 9 ]
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tjohn - 09 December 2013 11:14 PM

It would depend greatly on what you’re trying to make. A basketball? A planet?

Why would it “depend greatly”?

There’s no practical difference between a planet and a basketball, and used cylindrical maps (like the ones you linked to) on both planets and sporting goods before.

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Posted: 10 December 2013 12:32 AM   [ Ignore ]   [ # 10 ]
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RAMWolff - 09 December 2013 11:46 PM

Hi,

No, I’m looking for a way to UV map a sphere straight around so I can simply apply a texture map that follows it all the way round and blends at the seams.  I’ve tried Spherical and Cylindrical as well as trying out the default ZBrush mapping for the sphere. And while the ZBrush mapping is close it’s a bit chaotic in how it blends around the sphere.

Can we see one of these “chaotic” blends? And whatever is going wrong with the cylindrical maps? I’ve been using those for at least 15 years, without things getting “chaotic”.

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Posted: 10 December 2013 12:37 AM   [ Ignore ]   [ # 11 ]
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Here is a screen grab from my UV Mapping program.  This is a straight ZBrush mapping.  It’s the one on the left screen side.  Lower left side.  Notice in the mapped sphere how the mapping has a horrible jagged line butting up against the other.  YUKKY.  Can’t use this in animation. 

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Posted: 10 December 2013 03:06 AM   [ Ignore ]   [ # 12 ]
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RAMWolff - 10 December 2013 12:37 AM

Here is a screen grab from my UV Mapping program.  This is a straight ZBrush mapping.  It’s the one on the left screen side.  Lower left side.  Notice in the mapped sphere how the mapping has a horrible jagged line butting up against the other.  YUKKY.  Can’t use this in animation. 

Why don’t you use the UV Master plugin in ZB (which unwrap UV’s automatically) and resave the .obj? That will do.

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Posted: 10 December 2013 06:23 AM   [ Ignore ]   [ # 13 ]
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You are going to have a seam whatever you do, but if you use a plain mapping (by starting with a Poser or DS sphere primitive, for example) you will be able to use seamless patterns to wrap around the sphere without a visible join on a line of latitude. The poles would still need work, however, as the map gets very heavily squeezed.

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Posted: 10 December 2013 10:16 AM   [ Ignore ]   [ # 14 ]
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Alessandro_AM - 10 December 2013 03:06 AM
RAMWolff - 10 December 2013 12:37 AM

Here is a screen grab from my UV Mapping program.  This is a straight ZBrush mapping.  It’s the one on the left screen side.  Lower left side.  Notice in the mapped sphere how the mapping has a horrible jagged line butting up against the other.  YUKKY.  Can’t use this in animation. 

Why don’t you use the UV Master plugin in ZB (which unwrap UV’s automatically) and resave the .obj? That will do.

Yes, what you see up in my screen shot is a ZB created UV using the UV Master plugin!

Thanks Richard.  I think I tried the mapped Sphere directly from DAZ Studio.  I’ll look that over again .

Thanks.

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Posted: 10 December 2013 10:19 AM   [ Ignore ]   [ # 15 ]
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OMG… spank my bottom and call me Tina….. The sphere from DS is perfectly mapped.  Not sure what I was experiencing yesterday but ...... SIGH…. Thanks Richard.

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