It seemed that he didn't have a sync point.  I think you should take
the picture of the GPS-and zoom in to make sure the time is
legible...I learned that from experience :-)   Also, you need to be
careful to adjust the time you get in the picture of the GPS to the
same time zone (probably UTC) that your track logs are using when they
are imported.  The displayed GPS time is probably in your local time,
but the track logs are in UTC.

Also, I don't really trust my camera's clock-and matching where you
think a few key pictures were taken with the results  you get is a
good idea.

Oh, and double check that the date and time stamps in your GPX files
match reality.  There are some programs that are spitting out
malformed timestamps in GPX files, and my favorite gps utility mostly
does not attempt to parse malformed xml (I think the author's words
included the phrase life's too short :-).  It goes beyond not parsing
it...it can end up as a totally whacked value.

And don't forget that once you can locate pictures via time stamps you
can locate all sorts of travel ephemera, like receipts and museum
tickets, train tickets, speeding tickets, anything with a time stamp
that you trust...



On 8/30/06, Andy Armstrong <[EMAIL PROTECTED]> wrote:
On 30 Aug 2006, at 10:04, Rich Gibson wrote:
> Calculating offsets can be a bit of a pain if you don't have a sync
> point, but the key is to iterate: geocode some photos with known
> locations, then see what the code says.

If the camera clock hasn't changed since the time you took the photos
you can calculate the exact time offset by taking a picture either of
the clock on your GPS or the clock on your computer (assuming it's
accurate). Then the time offset is the difference between the time
that the camera stamps your picture with and the time actually shown
in the picture.

Like this:

http://www.hexten.net/2006/08/08/camera-time-versus-real-time

--
Andy Armstrong, hexten.net

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--
Rich Gibson
Chief Scientist, Locative Technologies
http://mappinghacks.com
http://geocoder.us
http://testingrange.com
AIM period3equals
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