Irregular Polygon Fill Using Contour Encoding

Abstract

A filling algorithm for irregular polygons is described. This algorithm is oriented towards raster graphics and uses image memories as job areas. The algorithm is based on the encoding of polygon boundaries by contour following so that all topologies are successfully processed. Thus, concave or convex polygons, holed or not, including possibly duplicate points can be filled. It is quite robust and easy to implement. It uses systematic encoding without special cases. Only two bits for encoding are needed and, thereby, it is suitable for hardware implementation. This algorithm can be used in many fields such as image synthesis, 3D objects or mathematical surface displays with hidden parts.

Evaluation of the Storm Prediction Center’s Day 1 Convective Outlooks

“…This is accomplished by plotting the outline of a polygon, then using a contour-encoding technique (Gourret and Paille 1987) to fill the risk area with a numeric value representing each risk level. For those instances in which a risk level was skipped by the SPC, the area is assigned the same risk as the next highest risk level.…”

Applying Rounding‐Up Integral Linear Interpolation to the Scan‐Conversion of Filled Polygons

“…Algorithms for drawing filled polygons have been devised by a number of authors [8][9][10][11][12][13] . They can be categorized as either region-filling algorithms or scan-line algorithms.…”

“…This problem should also be considered when designing polygon filling algorithms using region-filling methods, but it is often the case that it is neglected, as we can see in Ref. 8 where the polygon boundaries are drawn using a line scan-conversion algorithm such as Bresenham's algorithm 14 or symmetrical DDA 4 . In both cases the problem of polygon overlap is ignored.…”