[Proj] D-Sat 1 coordinates

[Mikael Rekola]

Robert Jaeschke <robert-j at gmx.de> wrote:

> So my question is: has anybody an idea, which projection/datum has been
> used for the city database or the satellite pictures? I'm sure that the
> data inside the city database is somewhat reasonable, because it gives me 
> a good map of Germany (see URL above). But the difference between
> screen-data and database data or database data and real data seems to be
> random. Maybe the rumour is true, that the satellite pictures are very
> badly geo-referenced and so my approach is senseless?
> 
> Thank you very much,
> Robert Jaeschke

Hello.

You should consider the possibility that the coordinates might actually
be stored as floating point numbers.

Suppose the coordinates are stored as doubles and the first eight bytes
are the easting and the next eight bytes the northing.

For a few test cases we get these coordinates:

Alsenz 414510.2 5516851.0
Alt Golm 850099.6 5814692.5
Alt Rehse 776849.4 5942433.0
Alt-Schadow 839608.2 5793427.0

Let's assume the coordinates are in zone 3. If we add the zone prefix
to each easting and run the coordinates through proj, we get the
following results:

% cs2cs +init=epsg:31463 +to +proj=latlong +datum=WGS84
3414510.2 5516851.0
7d48'43.002"E   49d46'55.564"N 3.915
3850099.6 5814692.5
14d8'20.298"E   52d21'12.861"N -8.845
3776849.4 5942433.0
13d10'33.442"E  53d32'25.104"N -10.966
3839608.2 5793427.0
13d57'51.194"E  52d10'11.168"N -8.124

The results are shifted a few kilometers to north, but still, I think
they seem somewhat promising.

--
Mikael Rekola