On Fri, May 29, 2009 at 8:52 PM, Robin Mills <robin@xxxxxxxxxxxxx>
wrote:
There's code on clanmills.com that does it:
http://www.clanmills.com/articles/gpsexiftags/gps_py.shtml
It reads GPX files and builds a dictionary called timedict (with
<time>
<position> information).
Then it loops over the images and gets their time stamp (from
exif). It
finds the closest timestamp (using search) and gets the <position>
from
timedict. Then it creates the exif GeoTags and writes out the
meta data.
A couple of comments:
1) there's some stuff to deal with time formats and tzinfo -
however those
details simply mask the simplicity.
2) Would you like some testdata - photos without GeoTags and a GPX
file?
Pretty simple, no? Python is a beautiful language.
On Sun, May 31, 2009 at 8:46 PM, <robin@xxxxxxxxxxxxx> wrote:
However I haven't really made progress with the action script.
I'm kind
of puzzled by how to interface this into your system.
Don't worry Nadia will come to rescue you ;-)
When my script runs
I want to know:
1) path to an gpx file (or directory with one or more gpx files)
2) path to an image (or images) to geotag
3) tzdiff (seconds) between GPX time (UTC) and Exif time (some
local time)
I want to avoid read/build timedict for every image and simply
that that
once then apply it to every image.
I looked at several scripts (shadow.py, rename.py and round.py).
And I
looked at the web documentation. Then I gave up and thought "Oh,
Stani
will set up the framework in no time at all. I'll push back on him!"
Robin
So Robin and Nadia,
This would be my ideal scenario, feel free to do with it what you
want. The structure of your current script doesn't work for Phatch as
Phatch gets the responsability about looping over the images. The
order of the images in Phatch is alphabetical by full path name. So
this might not necessarily be the time order of the files, but in most
cases it probably will. (Unless there are cameras which count down the
filenumbers.)
What I would like, is if your script is refactored in a module, which
can land in the phatch/core/lib folder. The module is than imported in
the action. Once it is a module, it will be also more easy to be used
by other python programs ;-) Robin, as you are the author, you decide
on the license, which should be compatible with the GPL3 and any later
version of it (such as GPL3 itself, LGPL3, FreeBSD, public domain, see
for a full list:
http://www.gnu.org/philosophy/license-
list.html#GPLCompatibleLicenses).
Mentioning the license is obligatory, otherwise it will block Phatch
from being accepted in Debian.
I've prepared a template for the gps action which should get you
going: phatch/actions/gps.py. I created it from the rename action, so
please modify any metadata which refers to that (such as email,
__doc__, ...) I am sure Nadia can help you where needed, for example
to look for a nice icon and embed it in the source code.
The gps module needs to provide a function (eg add_metadata), which
can work on an individual image at the time. Parameters which are not
file specific (such as timedict) should be passed as an argument to
that function. In the action source code we use the cache to store
these parameters. Cache parameters should be prefixed (in this case
with "gps_"), so that there is no namespace collision. I've also
stored timeshift in the cache which normally I prefer not too. As any
field can use variables which are specific to a certain image. However
I don't think someone wants to derive the timeshift from the filename,
so I assume it is safe to put in the cache. It would be better if
Phatch also allows actions to calculate cache before the loop takes
place and that fields can optionally forbid variables so that their
values can be used for sure in the cache.
To answer your questions:
1) path to an gpx file (or directory with one or more gpx files)
See the ReadFileField (which is defined in
phatch/core/lib/formField.py line 543). We can later specify a
specific gpx field. Do you plan to add more support for other formats
later?
2) path to an image (or images) to geotag
The gps action will apply the changes to the source file and only to
files saved by the save action of Phatch, if "copy metadata" is
enabled. This allows that the gps action (valid_last=True) can be used
without a save function or can be placed after a save function if you
want to add geo data not in the source but the saved file. Maybe this
is a bit confusing, but with a saved file I refer to the save action.
You'll get the path from
info = photo.get_info()
info['path']
3) tzdiff (seconds) between GPX time (UTC) and Exif time (some
local time)
See integerfield. Although I am wondering if it is not better to
delegate this to a seperate 'timeshift' action:
https://blueprints.launchpad.net/phatch/+spec/time-shift-action
The template is in rev 629. Please keep all mail correspondance on
phatch-dev (reply all). I hope everything is clear ;-) If you have any
comment, alternative suggestions, ... please let me know. I think
Robin, you can start refactoring your script in the module and Nadia
can already look for an icon, unless Robin has a nice icon already.
The license of the icon should be compatible with the GPL3, so no
creative commons.
Good luck and go for it!
Stani
PS Robin, this is not obligatory for your module, but if possible it
would be nice that during refactoring you switch your module so that
it follows PEP8 (Phatch code and actions should follow PEP8):
http://www.python.org/dev/peps/pep-0008/
