coords by GMDL

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June 22nd, 2007, 23:37
matrix681

coords by GMDL

Hi,
maybe this isn't the right place for this question, but i hope someone can help me.

I write a little programm in Java which use the filestructure of the maps downloaded with GMDL.
After using GMDL, there is also a file named coords.txt with 3 numbers in it.

now my question is: what are they?
or more specific: How can i know, which coordinate have the corners of the selected area, so i can compute my actual position given by my GPS-Mouse.

"71480 45440 0"
for example is the entry of coords.txt of a part from vienna.

thx in advance and kindly regards
Ahmet
June 23rd, 2007, 00:12
MIB.42

Quote:

Originally Posted by matrix681

Hi,
maybe this isn't the right place for this question, but i hope someone can help me.

I write a little programm in Java which use the filestructure of the maps downloaded with GMDL.
After using GMDL, there is also a file named coords.txt with 3 numbers in it.

now my question is: what are they?
or more specific: How can i know, which coordinate have the corners of the selected area, so i can compute my actual position given by my GPS-Mouse.

"71480 45440 0"
for example is the entry of coords.txt of a part from vienna.

thx in advance and kindly regards
Ahmet

These are the base coords and base zoom level. The first 3 entries in the GPSFS.
June 23rd, 2007, 11:03
AstroMo

MIB.42

How is the number "71480 45440 0" related to Latitude and Longitude ?

Thank you,
Anat
June 23rd, 2007, 17:14
matrix681

Quote:

Originally Posted by AstroMo

MIB.42

How is the number "71480 45440 0" related to Latitude and Longitude ?

Thank you,
Anat

that was my question :)
June 24th, 2007, 17:39
MIB.42

Quote:

Originally Posted by matrix681

"How is the number "71480 45440 0" related to Latitude and Longitude ?"
that was my question :)

Oh ok...

These numbers are a coordinate pair in par with what mapping solutions ( like Google Maps ) use to identify tiles. They encode zoom level information on top of the lat/lon as well. There is a conversion process for acquiring the lat/lon values ( using transverse mercator projection ) from these. It involves conversions from 2D units (like pixels) to geocentric degrees and radians. More detail on the math is available in the source files, look for initLatLon(), getLatLong() and getTileCoord() functions in main.c

Cheers,
MIB.42
June 24th, 2007, 23:32
matrix681

puh, found it :)

i hope. i can understand it :)