On 2/2/06, Jeff de La Beaujardiere <[EMAIL PROTECTED]> wrote: > Eijnden, B. van den (Bart) wrote: > > just reporting back something which had never struck my eye, but which I > > noticed when comparing Mapserver's WMS output to Ionic's WMS output, is that > > the output from Ionic is a lot smoother with respect to feature borders. Is > > this due to GD? > > The Ionic image is anti-aliased, the Mapserv one is not. > Notice that the file size of the Ionic image is ~3* greater. > > Mapserv does not appear to support anti-aliasing, except for > text and symbols. > (http://lists.umn.edu/cgi-bin/wa?A2=ind0411&L=mapserver-users&D=0&I=-3&X=638C7737989424DD73&P=75934) > However, GD supposedly does have anti-aliasing > (http://www.boutell.com/gd/manual2.0.33.html).
Bart, Jeff is right that Ionic is antialiasing the polygon edges. For those with poor eyes like me, I have prepared zoomed in views of Bart's images to see the effect up close. http://www.gdal.org/tmp/bodem50_close.png http://www.gdal.org/tmp/mapserv_close.png Note that the ionic (bodem50) image has a smeary effect between abutting green polygons? This is also an effect (mostly undesirable in my opinion) of the antialiasing. That said, it would be nice if we could antialias polygon edges too. GD does have some degree of support for it, though we might need to use polygon edges drawn as lines and anti-alias those. But I don't think this ought to be the default due to size, and imprecision of results (IMHO). Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, [EMAIL PROTECTED] light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent
