UV Mapping And You
Lyrra (Lyrra Madril)
Planar is the most commonly used method of mapping objects. Planar mapping splits your model into 'front' and 'back', depending on the angle you are viewing it from. Many character skins start with planar mapping; with mesh spreading used on the edges to uncompress the mesh segments. Animals are often mapped from the side, so a seam runs down the spine and the middle of the face. People are often mapped face-on, so the seam runs around the face, down the sides of the neck, tops and bottoms of arms, side of torso, sides of legs. Planar is also useful for anything that is flat.
Box mapping is the second most commonly used mapping, and most common for rectilinear objects. Picture a cardboard box. Now cut it apart at every edge. You will end up with six pieces – four sides, top and bottom. For objects that are cubical or rectangular this is the most efficient mapping. This is also the best place to start when examining a mesh for the first time.
Sphere, think of a globe. Cut it open from top to bottom, and along each latitude line on top and bottom. When it is spread out flat you will have a rectangle, with little saw-teeth at the top and bottom where the north & south poles were. Sphere maps are twice as wide as tall. There will be some distortion at the tops and bottoms when mapping spheres.
Cylinder, imagine a tube cut in a straight line down one side and flatted to create a rectangular surface. If the object is not hollow there will be smearing at the tops and bottoms of the cylinder so only use if the ends of the object are hidden.
Cylinder Cap is the same as cylinder, but the ends of the tube are mapped separately. This enables the texturing of the ends of the object without distortion.
Although most objects respond well to one kind of mapping, a complex object can have pieces that are best suited to different mapping techniques. Do not be afraid to experiment with different parts of your model in order to achieve the best map possible.
The goal is to make a texture with as few pieces as possible, making sure every surface has a flat and even mesh.
Many models available for free download have mapping issues. Often they do not have mapping coordinates at all. If you re-map a model with the intent to distribute texture, people will need your new version with the new UV information in order to use your templates and textures.
Remapping Models -- Copyright Issues
This also involves copyright issues. Make sure to check distribution rights with the creator before making your new version available. Many free models cannot be redistributed, so you will have to get the maker's permission, in writing, before doing so, to protect yourself against future legal action.
An alternative is to distribute the UVS information, which can be reapplied using UVmapper but does not distribute the copyrighted mesh itself. The drawback here is that novice users may have difficulty setting things up properly, so if you choose to use the UVs method, make sure to write a thorough readme file.
These are just the basics of Uvmapping, and of course the best way to become proficient with any program is to practice!
About Lyrra: Lyrra Madril is a professional freelance graphic artist and trainer. Previously from New York City, currently living in Delaware, Lyrra has had over ten years experience using and teaching various graphics packages in the advertising and corporate illustration business in NYC. Lyrra is also the Senior Poser Moderator here on Renderosity. In addition to digital art, she also makes Rennaisance costumes, custom VolksWagens, miniature dolls, crazy quilts, oil paintings, handdrawn science fiction/fantasy images and writes and composes songs.
Lyrra is currently teaching online Poser and Bryce classes at LVSonline.com.
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