Hi Even,
I just want to use the directory name to define the connection to
the
images, we could also provide to scan the files in subdirectories if
needed. I would prefer to have a new driver not just an offline tool
for
creating OGR datasets, in this case many existing applications (like
MapServer) would be capable to utilize this feature.
I could imagine a driver configuration file to specify which driver
should be used for a particular image format and where the specific
information is located, I don't require to harmonize the metadata
structure at this time. We should probably allow mixing jpegs and
tiffs
in the same directory, but the configuration should specify how the
similar attributes are provided by each (sub)driver.
Best regards,
Tamas
2012/7/23 Even Rouault <even.roua...@mines-paris.org
<mailto:even.roua...@mines-paris.org>>
Le lundi 23 juillet 2012 09:51:14, Tamas Szekeres a écrit :
> Hi All,
>
> We're thinking about implementing a new OGR driver which
would
represent a
> set of images as a vector data source. The images are taken
from
any GPS
> compatible mobile device, and each picture would be
represented
as a point
> feature, the positions would be extracted from the exif
information. The
> file name and path would be provided as an attribute for each
feature. This
> data source could then be used by higher level apps to
provide
symbols at
> the picture locations in the map and display the picture when
the
feature
> is selected. The driver would definitely use GDAL to extract
information
> about the provided images.
>
> I'm not sure whether we already have some kind of alternative
solution to
> this, let me know if you know about any. Further ideas about
this
topic
> would also be helpful.
The JPEG driver already exposes EXIF information if found :
$ gdalinfo ../autotest/gdrivers/data/albania.jpg
Driver: JPEG/JPEG JFIF
Files: ../autotest/gdrivers/data/albania.jpg
Size is 361, 260
Coordinate System is `'
Metadata:
[...]
EXIF_GPSLatitude=(41) (1) (22.91)
EXIF_GPSLatitudeRef=N
EXIF_GPSLongitude=(19) (55) (42.35)
EXIF_GPSLongitudeRef=E
[...]
$ gdalinfo ../autotest/gcore/data/exif_and_gps.tif -mdd EXIF
Driver: GTiff/GeoTIFF
Files: ../autotest/gcore/data/exif_and_gps.tif
Size is 1, 1
Coordinate System is `'
[..]
Metadata (EXIF):
[...]
EXIF_GPSLatitude=(77) (5) (60)
EXIF_GPSLatitudeRef=S
EXIF_GPSLongitude=(34) (12) (0)
EXIF_GPSLongitudeRef=E
[..]
Are you thinking to other raster formats to extract EXIF info
from?
To my
knowledge, the JPEG driver, and recently the GTiff driver, are
the
only one
that extract EXIF for now. I see that the JPEG driver exposes it
in the
default metadata domain, whereas I chose EXIF for the GTiff
driver.
For GTiff,
the specific EXIF metadata domain seemed better to me to avoid
'polluting' the
default metadata domain, but I didn't want to change the JPEG
driver
at that
point. But this would probably requires some harmonization.
So with some scripting, you could create for example a point
shapefile, with
the filename as attribute and GPS position as geometry.
In its syntax, this could be something similar to gdaltindex.
Doing that as a OGR driver would be also doable of course. The
only
point to
solve is the definition of the connexion string to specify the
image
set.
>
> Best regards,
>
> Tamas
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