[Proj] Little sphere projection

Clifford J Mugnier cjmce at lsu.edu
Sun Aug 7 21:49:59 EST 2011

For any individual Abbey, the azimuthal equidistant projection (originally invented by the monk, Postel) might do in either a spherical or an ellipsoidal case.  This projection is identical to what is viewed on a radar screen.  The French Hatt projection is one variant used for hydrographic projections of harbor surveys in the 19th and early 20th centuries.
Clifford J. Mugnier, C.P., C.M.S.
Chief of Geodesy,
Center for GeoInformatics
Department of Civil Engineering 
Patrick F. Taylor Hall 3531
Baton Rouge, LA  70803
Voice and Facsimile:  (225) 578-8536 [Academic] 
Voice and Facsimile:  (225) 578-4578 [Research] 
Cell: (225) 328-8975 [Academic & Research]
Honorary Life Member of the 
Louisiana Society of Professional Surveyors 
Fellow Emeritus of the ASPRS 
Member of the Americas Petroleum Survey Group


From: proj-bounces at lists.maptools.org on behalf of Carlo A. Bertelli (Charta s.r.l.)
Sent: Sun 07-Aug-11 16:16
To: proj at lists.maptools.org
Subject: [Proj] Little sphere projection

I'm trying a simplistic approach to a topological representation. I'm
mapping the possessions belonging to a group of abbeys in a regional
space. Il works well at a small scale, but when the abbeys are
clustered in major towns, the representation ties properties to the
cluster and not to the single abbey. The fact is that towns (and
clustering) play a significant role in this story (yes this happens in
the 18th century), asks for a better representation.
My idea is analysing each town cluster using a little sphere (or
ellipsoid) centered on the town whith an emisphere that only covers
the space of the region, so to show larger distances in town (so to
distinguish any abbey) and reduced distances far from the town center.
I think it should not be impossible to craft ad hoc projections, but I
have no idea on how to do it. Could someone help me?
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