[ka-Map-users] Optimizing map projection through changing map automatically based upon extent and scale?

[Steve Walker]

I have read the post and wiki about 'maintaning extents while changing
maps,' I have a question here which could almost be re-phrased as the
opposite:  'changing map while maintaining extents' - well almost.

What I would like to do is automatically switch between map files as the
extent and scale changes.

Example:  Begin with a map of the whole, which may be presented in a
Robinson projection, or (as is most often the case) unprojected lat-longs.

As a user zooms in and-or pans, switch to a map which utilizes  a
coordinate system (and perhaps different content) more appropriate to the
new extents and scale.

Thus, at the scale and extent of a given country, switch to a map whose
projection is optimal (or at least appropriate) for that country;

Zooming in further, switch to a map representing the appropriate UTM zone;
panning across UTM zones, seamlessly switch from one UTM map to another.

I can envision creating a set of invisible scale-specific, query-only
layers which would return an 'optimal' projection and map file name (the
six-degree-wide UTM zones are easiest to visualize here) based upon a
specific center-point-scale, then performing a coordinate transformation
on the center point xy using GEOS/PostGIS to return the transformed
coordinates.

This seems highly desirable (how many more lat-long maps must we endure!?)

Does this seem feasible?  Sorry I don't understand the JS code enough to
know where in the code to begin approaching the problem.

-Steve

-- 
Steve Walker
Middle Fork Geographic Information Services
walker at mfgis.com
360-671-2505