hi,
Aha! I have no clue about how such databases work, so your input is
valuable here!
PostgreSQL (with PostGIS) and mySQL (with its own spatial extension)
store so called simple features (those being points, lines and polygon
shapes). a GPS Long/Lat info is basically a point info. coordinates are
stored as int or floats depending on what's needed and the underlaying
coordinate system, but as a pair of numbers and not the funny EXIF
rational thing. geographic info as WGS84 is in a range of +/-180 and
-/-90, hence you will need a lot of decimal places for high accuracy on
the earths surface. at least 6 to 8 decimal places are needed.
A slight problem with this is that the floating point value has to be
converted to a rational value since that is what is used in the Exif
data. So your example becomes
476871293122 / 1000000000
but those numbers are too big for 32-bit signed integers.
yes, i saw that. there must be methods to overcome this here. take a
look at this geo-tagged photograph:
<http://www.carto.net/neumann/photographs/bremgarten_2005_12_03/06_bremgarten_railway_bridge.jpg>.
analyzing it's GPS info you get
GPSLatitude: 47/1 20/1 59374/1009
GPSLongitiude: 8/1 20/1 66921/2500
and the seconds ratio seems to be the trick here. i looked intp the exif spec and
this seems to be allowed... as i don't know how this is handled, i asked the author
of the photos. they are tagged with the perl based exiftool
(<http://www.sno.phy.queensu.ca/~phil/exiftool/>). maybe it is worth having a
look in there.
andré
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