Slightly offtopic - coordinate conversions

[Raphael Mankin]

They may well be completely different co-ordinate systems. The hnear
arguments may be in UTM  (or UK national grid for Britain). The
transformations are wildly non-linear.

See
http://www.colorado.edu/geography/gcraft/notes/mapproj/mapproj_f.html
or
Snyder JP, Map Projections: a working manual (USGS). A scanned version
of this book is available at http://pubs.er.usgs.gov/publication/pp1395,
but to order it on paper you have to phone the US Embassy and ask them
for the phone number of AIRS (American Information Retrieval Service).

On Wed, 2011-07-13 at 07:16 +0100, Peter Sergeant wrote:
> I've been playing around with Google Maps recently, and noticed that they've started using hashes of some coordinates:
> 
> latlng: 52.54296 -0.308166
> hnear : 0x4877f21032e242f5:0x805cb103d71d5051
> 
> latlng: 51.411586,-0.300893
> hnear : 0x47d8a00baf21de75:0x52963a5addd52a99
> 
> A few attempts at working out how this was done with Perl have failed me - anyone got a better idea?
> 
> -P