Hello; I have been experimenting with AGG in MapServer (CVS April 26/2007) using various OUTPUTFORMATs and found the results inconsistent. To experiment with various OUTPUTFORMATs (DRIVERs and IMAGEMODEs), a series of mapfiles were created that have a single line layer where all features are drawn as black lines with a width of one pixel.
DRIVER GD/GIF and IMAGEMODE PC256 The lines were rendered as expected. I performed this test as a baseline. http://dev.atlas.gc.ca/cgi-bin/mapserv_dev?map=/home/atlas/mapdata/english/pb_gd_gif_pc256.map&mode=map DRIVER AGG/PC256 and IMAGEMODE RGBA While anti-aliasing was present the pattern of the line was not consistent. Sometimes a solid line and other times there were gaps in the line. http://dev.atlas.gc.ca/cgi-bin/mapserv_dev?map=/home/atlas/mapdata/english/pb_agg_pc_rgba.map&mode=map DRIVER AGG/PNG and IMAGEMODE RGBA While anti-aliasing was present, the lines were gray and not black. In addition the pattern of the line was not consistent. Sometimes a solid line and other times there were gaps in the line. http://dev.atlas.gc.ca/cgi-bin/mapserv_dev?map=/home/atlas/mapdata/english/pb_agg_png_rgba.map&mode=map DRIVER AGG/PNG24 and IMAGEMODE RGBA While anti-aliasing was present, the lines were gray and not black. In addition the pattern of the line was not consistent. Sometimes a solid line and other times there were gaps in the line. http://dev.atlas.gc.ca/cgi-bin/mapserv_dev?map=/home/atlas/mapdata/english/pb_agg_png24_rgba.map&mode=map DRIVER AGG/JPG and IMAGEMODE RGBA While this produced the best rendering of the line, the background was pixelated around the line. http://dev.atlas.gc.ca/cgi-bin/mapserv_dev?map=/home/atlas/mapdata/english/pb_agg_jpg_rgba.map&mode=map DRIVER AGG/GIF and IMAGEMODE RGBA While anti-aliasing was present the pattern of the line was not consistent. Sometimes a solid line and other times there were gaps in the line. http://dev.atlas.gc.ca/cgi-bin/mapserv_dev?map=/home/atlas/mapdata/english/pb_agg_gif_rgba.map&mode=map It is not clear to me why gray and/or lines with inconsistent patterns were returned. Are the DRIVER/IMAGEMODE conbinations I am using not compatible with one another? Or am I missing something else. The symbol definition I am using for the lines in the mapfiles is: SYMBOL TYPE ELLIPSE NAME solidline POINTS 1 1 END FILLED true END Any insight to the problems I am having is appreciated. Peter Bruton
