[Qgis-developer] ​Geophoto management

[Mark Johnson]

​Work is being done in this area, intended to be an extension of the
RasterLite2 library (of the spatialite project), which will hopefully come
out this year.

The Raster-support in RasterLite2 supports Georeferenced images called
Raster-Coverage's.

The idea would be to add support for Geotaged images in the form of an
'Album'
- one Album containing images
- each Album could belong to another Album

For each Image, the Exif-Information would be extracted and stored in the
row together with the original image.
- spatialite already has reading capabilities for Exif-Information (but at
the moment no writing)
The GPS-Information is then stored in a MULTIPOINT Geometry
- 2 points if GPSDest* Information was found

Since the Exif-Information is stored in the row
- the idea would be that it could be changed and the image updated (and
exported)

Based in the existing RasterLite2 logic, where there is an extra TABLE
containing a summery of Information about for each Raster-Coverage
- there would be a corresponding 'Album-Coverage' would exist with one
entry per Album (as a summery), containing
-- the area the photos inside the Album contains --> to zoom to the area
-- a MULTILINE GEOMETRY which shows all the LINESTRING that exist in the
Album
-- a MULTIPOINT GEOMETRY which shows all the images that do not have
GPSDest* Information
-- an GEOMETRYCOLLECTION, containing both) also exists, but in my version
of QGIS at least,  GEOMETRYCOLLECTION cannot be displayed
- Bearing and distance being calculated when possible.

This had be developed about 2 years ago for a historical Database project
- about 600 images were at that time collected
- short (title) long (image description) where collected an added with the
exiftool
-- setting fields used by linux, mac and windows file explorers (each
system using different fields)
- the estimated position where the photo was shot from being set as the
GPSLat/Long value
- the main point of interest set as the GPSDest* value

The RasterLite2 tool 'rl2sniff' was initially used as a base
- which runs through a directory, searching for Georeferenced images

This tool was adapted (called 'rl2sniff_album') to also look for geotagged
images
- and add it to the Database
-- after a refresh in QGIS, the POINTS or LINESTRINGs show up so that
correction can be made when needed

So much of what of what is being requested, is being considered and at the
moment I am working
on moving the present logic from the rl2-tool into RasterLite2-Library so
that it can be SQL-Driven
- retrieve, Import, Export, update

My intention was to suggest this to Sandro after the first release of
RasterLite2
- but since this has been delayed, I am working on this now and will summit
the concept when completed
  (So Sandro has no idea about this concept of adding the 'poor cousin'
geotaged images to RasterLite2)

As for the importing of external 'RAW' files
- at the moment the idea was to support the exiftool-json format
-- so that when a non-geotaged image was found, but a exiftool-json
existed, that would be used
    (just as is done with a tif with a world file)
So adding a reading support for these RAW-files using the same logic would
be practicable

The present documentation is based on the code of 2 years ago, but will be
updated when the integration has been completed.

Mark Johnson, Berlin Germany
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