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The clip coordinate system is a homogeneous coordinate system in the graphics pipeline that is used for clipping. [1]Objects' coordinates are transformed via a projection transformation into clip coordinates, at which point it may be efficiently determined on an object-by-object basis which portions of the objects will be visible to the user.
These are the coordinates on M obtained by introducing the standard spherical coordinate system on the Euclidean space T p M. That is, one introduces on T p M the standard spherical coordinate system (r,φ) where r ≥ 0 is the radial parameter and φ = (φ 1,...,φ n−1) is a parameterization of the (n−1)-sphere.
In contrast, the viewport is an area (typically rectangular) expressed in rendering-device-specific coordinates, e.g. pixels for screen coordinates, in which the objects of interest are going to be rendered. Clipping to the world-coordinates window is usually applied to the objects before they are passed through the window-to-viewport ...
Homogeneous coordinates are not uniquely determined by a point, so a function defined on the coordinates, say (,,), does not determine a function defined on points as with Cartesian coordinates. But a condition f ( x , y , z ) = 0 {\displaystyle f(x,y,z)=0} defined on the coordinates, as might be used to describe a curve, determines a condition ...
More specifically, if and ′ are homogeneous normalized image coordinates in image 1 and 2, respectively, then (′) =if and ′ correspond to the same 3D point in the scene (not an "if and only if" due to the fact that points that lie on the same epipolar line in the first image will get mapped to the same epipolar line in the second image).
The choice of an origin and an orthonormal basis forms a coordinate frame known as an orthonormal frame. For a general inner product space , an orthonormal basis can be used to define normalized orthogonal coordinates on . Under these coordinates, the inner product becomes a dot product of vectors.
n-vector is a one-to-one representation, meaning that any surface position corresponds to one unique n-vector, and any n-vector corresponds to one unique surface position. As a Euclidean 3D vector, standard 3D vector algebra can be used for the position calculations, and this makes n-vector well-suited for most horizontal position calculations.
The camera matrix derived in the previous section has a null space which is spanned by the vector = This is also the homogeneous representation of the 3D point which has coordinates (0,0,0), that is, the "camera center" (aka the entrance pupil; the position of the pinhole of a pinhole camera) is at O.