Slightly offtopic - coordinate conversions

Raphael Mankin raph at
Wed Jul 13 09:44:46 BST 2011

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.

Snyder JP, Map Projections: a working manual (USGS). A scanned version
of this book is available at,
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 

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