artemp/trac2github — Issue #851: Native support for detecting 'geographic' srs's
Author: artemp
Created: 2011-10-09 20:53:15+00:00
State: open
Labels: Core_Library

#839 tracks the idea of adding custom, fast transforms for certain simple and common srs's. But, for this to work we would also need to detect if the srs is 'geographic' for proper calculation of scale denominators (zoom levels). Really all mapnik cares about is whether to convert from degrees to meters: http://trac.mapnik.org/browser/trunk/src/scale_denominator.cpp#L38 but the meaning basically if it is "unprojected" long/lat or platte carre: http://mathworld.wolfram.com/EquirectangularProjection.html