This document discusses different algorithms for filling polygons, including: - The scanline algorithm, which works by intersecting a scanline with polygon edges and filling between pairs of intersections from bottom to top. - Boundary fill algorithms using 4-connected or 8-connected pixels to replace the interior color of a polygon with a fill color by recursively checking neighboring pixels. - The odd-even rule algorithm which determines if a point is interior or exterior by counting the number of edge crossings along a line from that point, with odd numbers indicating interior.