[Proj] Little sphere projection

[Jan Hartmann]

Are these the kind of maps you mean:

http://www-personal.umich.edu/~mejn/cartograms/

These are "cartograms", distorted maps on the basis of some sort of 
density distributions. There is a complete book with hundreds of examples:

http://www.amazon.com/Atlas-Real-World-Daniel-Dorling/dp/0500514259

The authors have made available the software 
(http://www-personal.umich.edu/~mejn/cart/). I got it working some time 
ago, but you need to know a bit about low-level compiling. 
Alternatively, there is a tool for ArcGIS 
(http://blogs.esri.com/Info/blogs/gisedcom/archive/2009/10/16/exploring-data-using-cartograms-within-arcgis-desktop.aspx).

Cartograms are real fun, so I hope you can do something with them for 
your subject.

Cheers,

Jan

On 08/09/11 13:02, Mikael Rittri wrote:
> Carlo Bertelli wrote:
>
>> 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.
> If I understand you right, you want your map to be distorted
> in the same way as M. C. Escher's Balcony,
>
> http://www.worldofescher.com/gallery/A3.html
>
> where the central balcony is shown in a large (detailed) scale,
> but surrounding areas are shown in much smaller scale.
>
> In Escher's print, the scale has stabilized when you get to the
> print edges, but that's not necessary.
>
> I haven't seen such map projections used for cartography, except
> for patriotic joke maps, where one's beloved home town or country
> is shown in a much larger scale than the rest of the world. But
> maybe such projections are used for statistical or economic maps,
> as you suggest.  I doubt there is anything appropriate in Proj.4,
> though.
>
> One could make a new kind of azimuthal map projection for this
> purpose.  The azimuth (direction) from the town center could be
> preserved (because, why not?).  The true distance from the town
> center could be represented by a shorter map distance.  The
> mathematical function that converts true distance to map distance
> should have slope 1 for short distances, but gradually get lower
> slope.  Something like arctan or tanh, perhaps.
>
> Best regards,
>
> Mikael Rittri
> Carmenta
> Sweden
> http://www.carmenta.com
>
> -----Original Message-----
> From: proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] On Behalf Of Carlo A. Bertelli (Charta s.r.l.)
> Sent: den 7 augusti 2011 23:17
> To: proj at lists.maptools.org
> Subject: [Proj] Little sphere projection
>
> Hello,
> 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?
> TIA
> c
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