HIDDEN-CURVE ALGORITHM FOR CORRECT GRID SURFACE REPRESENTATION OF FUNCTIONS OF 2 VARIABLES

A common method for visualizing a function of two variables is to cons ider it as a nontransparent grid surface in 3-D space and to project i t onto a view plane. Various computer algorithms exist which map such surfaces onto a screen. Each of these conventional techniques has its own disadvantage: either the graphical results are not very accurate, because the algorithm approximates the surface by a polygon mesh consi sting of quadrilaterals or, indeed, the algorithm produces sufficientl y true images of the grid curves, but is restricted to special viewing conditions. This paper gives details and a pseudocode of a new, unive rsal line-drawing algorithm which yields correct images of grid surfac es conserving their geometrical properties such as smoothness or disco ntinuities. The functions to be represented may be continuous or piece wise continuous. Almost any position of the surface in relation to the viewer's eye and in relation to the view plane can be chosen and any parallel or perspective projection can be applied. (C) 1996 Elsevier S cience Ltd