3D graphics eBook - Course Materials Repository

UVW mapping 225
UVW mapping
UVW mapping is a mathematical technique for coordinate mapping. In computer graphics, it is most commonly a
to map, suitable for converting a 2D image (a texture) to a three dimensional object of a given topology.
"UVW", like the standard Cartesian coordinate system, has three dimensions; the third dimension allows texture
maps to wrap in complex ways onto irregular surfaces. Each point in a UVW map corresponds to a point on the
surface of the object. The graphic designer or programmer generates the specific mathematical function to
implement the map, so that points on the texture are assigned to (XYZ) points on the target surface. Generally
speaking, the more orderly the unwrapped polygons are, the easier it is for the texture artist to paint features onto the
texture. Once the texture is finished, all that has to be done is to wrap the UVW map back onto the object, projecting
the texture in a way that is far more flexible and advanced, preventing graphic artifacts that accompany more
simplistic texture mappings such as planar projection. For this reason, UVW mapping is commonly used to texture
map non-platonic solids, non-geometric primitives, and other irregularly-shaped objects, such as characters and
furniture.
External links
• UVW Mapping Tutorial [1]
References
[1] http:/ / oman3d. com/ tutorials/ 3ds/ texture_stealth/
Vertex
In geometry, a vertex (plural vertices) is a special kind of point that describes the corners or intersections of
geometric shapes.
Definitions
Of an angle
The vertex of an angle is the point where two rays begin or meet,
where two line segments join or meet, where two lines intersect
(cross), or any appropriate combination of rays, segments and lines that
result in two straight "sides" meeting at one place.
Of a polytope
A vertex is a corner point of a polygon, polyhedron, or other higher
dimensional polytope, formed by the intersection of edges, faces or
facets of the object: a vertices''''''''''''''''facts.
In a polygon, a vertex is called "convex" if the internal angle of the
polygon, that is, the angle formed by the two edges at the vertex, with
A vertex of an angle is the endpoint where two
line segments or lines come together.
the polygon inside the angle, is less than π radians; otherwise, it is called "concave" or "reflex". More generally, a
vertex of a polyhedron or polytope is convex if the intersection of the polyhedron or polytope with a sufficiently
small sphere centered at the vertex is convex, and concave otherwise.