On 6/4/07, Lars Aronsson <lars(a)aronsson.se> wrote:
Andre Engels wrote:
When would someone like to use that picture in
Wikipedia or a
Wikibook or whatever? When they're talking about the village, I
assume.
This position is untenable. Have you tried to geotag any
significant amount of images that way? You cannot accurately
measure the latitude and longitude of the object you are
capturing. It might be quite large. Or it might be two different
objects at different locations (another building in the foreground
and the Eiffel tower far behind). The only sustainable policy is
to register the point position of the photographer and, if
possible, the pointing direction of the lens.
If you're going to do that, might as well include some indication of the
effective focal length.
But that's far from the *only* sustainable policy. In fact, in some cases
it is impossible to know the position of the photographer but it is possible
to know the position of the subject. A good geotagging system is going to
allow for both - informally if not formally.
If you want to find
photos of the Eiffel tower, you need to search for
photos that are
tagged in a surrounding region.
So a satellite photo of the Eiffel tower would be tagged with the position
of the satellite? Doesn't seem reasonable.
There is a discussion and illustration at
Right, take that photo in the example and pretend we don't know the position
of the photographer. Also assume we don't know the focal length, or type of
camera, or even whether or not the image has been cropped. There's no easy
way to extract the location of the photographer from just that photograph.
You can, however, tag the image with the location of one of the two
buildings, or even both of the two buildings. If you do know the location
of the photographer, you could even tag all three points, hopefully with
some metadata saying that one of the three points was the photographer's
location.