What's the difference between a UV texture coordinate vs. ST texture Coordinate?
I know that UV and ST are used in OpenGL.
I also know that ST are also used in Java.
UV mapping is the 3D modeling process of projecting a 2D image onto a 3D model's surface. The term “UV” refers to the bidimensional (2D) nature of the process: the letters “U” and “V” denote the axes of the 2D texture because “X”, “Y” and “Z” are already used to denote the axes of the 3D model.
The UV mapping process involves assigning pixels in the image to surface mappings on the polygon, usually done by "programmatically" copying a triangular piece of the image map and pasting it onto a triangle on the object.
Texture coordinates define how an image (or portion of an image) gets mapped to a geometry. A texture coordinate is associated with each vertex on the geometry, and it indicates what point within the texture image should be mapped to that vertex.
UV mapping is a technique used to "wrap" a 2D image texture onto a 3D mesh. "U" and "V" are the names of the axes of a plane, since "X", "Y" and "Z" are used for the coordinates in the 3D space.
Computer graphics principles and practice (Foley et al) defines the 2 as follows:
Texture mapping can be accomplished in two steps. A simple approach starts by mapping the four corners of the pixel onto the surface. For a bicubic patch this mapping naturally defines a set of points in the surface's (s,t) coordinate space. Next, the pixel's corner points in the surface's (s,t) coordinate space are mapped into the texture's (u,v) coordinate space The four (u,v) points in the texture map define a quadrilateral that approximates the more complex shape into which the pixel may actually map due to surface curvature. We compute a value for the pixel by summing all texels that lie within the quadrilateral, weighting each by the fraction of the texel that lies within the quadrilateral. If a transformed point in (u,v) space falls outside of the texture map, the texture map may e though of as replicated, like the patterns of Section 2.1.3 Rather than always use the identity mapping between (s,t) and (u,v), we can define a correspondence between the four corners of the 0-to-1 (s,t) rectangle and a quadrilateral in (u,v). When the surface is a polygon, it is common to assign texture map coordinates directly to its vertices.
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