A two dimensional space used to represent surface orientation in terms of its vertical and horizontal components. Thus the plane surface −Z = P. X + Q. Y + C is represented by the point (P. Q) in gradient space. The steepness of the surface is squareroot(P2 + Q2) and the direction of the slope is tan−1(Q/P). Such a representation does not make explicit the spatial location or extent of surface planes. Convex and concave edges and curvatures will be represented by lines in the gradient space, in the case of planar surface discontinuity edges these will be perpendicular to the edge in the image space, with order along the line determined by the convexity/concavity.
- [Draper 81]Draper. S. W. The Use of Gradient Space and Dual Space in Line Drawing Interpretation. Artificial Intelligence 17, 1981.Google Scholar