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  2. Homogeneous coordinates - Wikipedia

    en.wikipedia.org/wiki/Homogeneous_coordinates

    If homogeneous coordinates of a point are multiplied by a non-zero scalar then the resulting coordinates represent the same point. Since homogeneous coordinates are also given to points at infinity, the number of coordinates required to allow this extension is one more than the dimension of the projective space being considered. For example ...

  3. Cross-ratio - Wikipedia

    en.wikipedia.org/wiki/Cross-ratio

    Definition in homogeneous coordinates [ edit ] If four collinear points are represented in homogeneous coordinates by vectors α , β , γ , δ {\displaystyle \alpha ,\beta ,\gamma ,\delta } such that γ = a α + b β {\displaystyle \gamma =a\alpha +b\beta } and δ = c α + d β {\displaystyle \delta =c\alpha +d\beta } , then their cross-ratio ...

  4. Quadratic form - Wikipedia

    en.wikipedia.org/wiki/Quadratic_form

    Using homogeneous coordinates, a non-zero quadratic form in n variables defines an (n − 2)-dimensional quadric in the (n − 1)-dimensional projective space. This is a basic construction in projective geometry. In this way one may visualize 3-dimensional real quadratic forms as conic sections.

  5. Duality (projective geometry) - Wikipedia

    en.wikipedia.org/wiki/Duality_(projective_geometry)

    Switching to homogeneous coordinates using the embedding (a, b) ↦ (a, b, 1), the extension to the real projective plane is obtained by permitting the last coordinate to be 0. Recalling that point coordinates are written as column vectors and line coordinates as row vectors, we may express this polarity by:

  6. Plücker coordinates - Wikipedia

    en.wikipedia.org/wiki/Plücker_coordinates

    Each Plücker coordinate appears in two of the four equations, each time multiplying a different variable; and as at least one of the coordinates is nonzero, we are guaranteed non-vacuous equations for two distinct planes intersecting in L. Thus the Plücker coordinates of a line determine that line uniquely, and the map α is an injection.

  7. Homogeneity (disambiguation) - Wikipedia

    en.wikipedia.org/wiki/Homogeneity_(disambiguation)

    Homogeneous catalysis, a sequence of chemical reactions that involve a catalyst in the same phase as the reactants Homogeneous (chemistry) , a property of a mixture showing no variation in properties Homogenization (chemistry) , intensive mixing of mutually insoluble substance or groups of substance to obtain a soluble suspension or constant

  8. Line coordinates - Wikipedia

    en.wikipedia.org/wiki/Line_coordinates

    A linear equation in line coordinates has the form al + bm + c = 0, where a, b and c are constants. Suppose (l, m) is a line that satisfies this equation.If c is not 0 then lx + my + 1 = 0, where x = a/c and y = b/c, so every line satisfying the original equation passes through the point (x, y).

  9. Triangulation (computer vision) - Wikipedia

    en.wikipedia.org/wiki/Triangulation_(computer...

    where ′, ′ are the homogeneous coordinates of the detected image points and , are the camera matrices. x (3D point) is the homogeneous representation of the resulting 3D point. The ∼ {\displaystyle \sim \,} sign implies that τ {\displaystyle \tau \,} is only required to produce a vector which is equal to x up to a multiplication by a non ...