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View Full Version : How to stretch a texture from "planar-mapped" to "cylindrical mapped".


joeniemeloenie
08-27-2007, 10:22 PM
hay,


I projected a picture onto a head-model using planar mapping. The texture falls nice onto the front of the face, but the planar projection keeps me from being able to texture/paint the ears, sideburns,... (see extra pictures attached below)

http://www.wickstonia.be/cgtalk/head.jpg

If I switch to "cylindrical mapping" I DO have the ability to texture or paint the ears, sideburns,... but then I lose that 'nice' texture coverage on the face...That would force me to dig into photoshop to stretch and tweak the picture... (that would take me too much time to do, I'm not good with photoshop).

So actually, what I want to do is:
when switching from "planar mapping" to "cylindrical mapping" I want to have the texture 'stretch' along with the UV's...so I want to have a stretched texture as a result.

in other words:
I want to switch from planar- to cylindrical mapping; with the resulting texture on the face looking exactly like it does now.


*also, you might have noticed in the attached pictures that there are shadows on the face-picture, which isn't by the right way to shade a head...but then again I'm not planning to light the scene at all; I'm using a surface shader. The lighting has to be exactly as it is on the picture, that's why...and also because it's much less work (tight deadline)

I hope you can understand what I'm trying to say...it's kinda hard to explain.


Thanks in advance!!

Emil3d
08-28-2007, 12:38 AM
Make multiple planar projections and after each bake the textures. Open the different textures as layers in Photoshop, delete the bad parts from each texture and combine the best parts into one.

Stahlberg
08-28-2007, 07:22 AM
You have to do some UV mapping.
In this case I might just select all the UV points that show stretching, leave the ones that render ok, and use the Unfold tool. If that doesn't work, keep the same selection and do a planar UV mapping from the side on them, then some manual moving around.

Emil3d
08-28-2007, 04:23 PM
Hey joeniemeloenie, I replied hastily without paying close attention and bothering to look at your attached images thinking that you have problems with texture projections while you are struggling with UV projections. Sorry for that and the vague message. Iíll elaborate now.

Stahlberg is right, first you have to unfold your UVs (remove any overlaps). Your cylindrical mapping is almost there. You have to cut the UVs of the ears along an edge loop, move them away and unfold as separate UV shells since it would be impossible to fit them with the rest of the UV mesh without extreme texture distortions. You can keep and unfold the rest of the UVs as one shell. You will have some texture stretching here and there, especially on the top of the head and under the chin area but thatís tolerable. Then since you have a photo of a face apply the texture as projection from the same camera angle as the photo and it will fit perfectly when viewd from that angle. You can now bake this texture. Then you need a profile photo of the person and apply a new texture projection this time from the side. After baking this texture too, you can open and blend the two textures in Photoshop to unfold the photo image matching your UVs. Of course more photos from different angles you have the better but two photos front and side should be enough to cover most important parts of the face sufficiently.

Hope this helps

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