[Kde-imaging] [Bug 140297] GPS kipi plugin truncates input coordinates, introducing inacuracy

[Arnd Baecker]

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http://bugs.kde.org/show_bug.cgi?id=140297         




------- Additional Comments From arnd.baecker web de  2007-03-06 09:57 -------
To summarize the thread Fabien points to in #2:

- exiv2 can provide enough digits (i.e. it is not the culprit ;-)
- digikam itself can deal with more accurate GPS coordinates
- but: the "Edit geographical coordinates" tool does not write 
  the necessary number of digits on save.

Gilles then wrote:
"""This is relevant of the of following Exiv2Iface methods :

- setGPSInfo()
- convertToRational()

... where digits are lost during double to rational conversion.

http://websvn.kde.org/trunk/extragear/libs/kipi-plugins/common/exiv2iface/exiv2iface.cpp?rev=606701&view=auto

Andreas, There is method in Exiv2 to do this conversion without lost digits ?
If i can use it instead Exiv2Iface::convertToRational()..."""

Andreas' reply on this:
"""There is no such method in Exiv2. If you are happy with 7 decimal places, you could use a simple conversion algorithm similar to that in crwimage.cpp, from line 1015; that should just fit into 32 bit unsigned ints. (Search for "primitive conversion" in the file.)

http://dev.robotbattle.com/~cvsuser/cgi-bin/ns_viewcvs.cgi/exiv2/trunk/src/crwimage.cpp?rev=861&view=markup
"""

My impression is that 7 decimal places would be sufficient,
also in view of Andreas' accuracy analysis given in the thread in #2.
The code of the primitive conversion is just a few lines, so
it might not do much harm to directly include it?