[Interest] Qt Location GeoServices plugin to use geo-referenced image file as map source

[Richard Lang]

Repost of question asked on Qt Forums and raised as a feature request on 
the bug tracker...

https://forum.qt.io/topic/85704/qt-location-geoservices-plugin-to-use-geo-referenced-image-file-as-map-source

https://bugreports.qt.io/browse/QTBUG-65018?jql=project%20%3D%20QTBUG

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I'm currently working on a Qt Quick application that will provide a map 
viewer for a smallish area (1 square KM or so), the map details for 
which will be provided in a single geo-referenced image file (GeoTIFF, 
geo-referenced PDF, ESRI Shape file etc.), along with display of current 
location, operator identified points of interest etc. It's primarily 
responsibility is the display of custom maps (as opposed to generic maps 
retrieved from public map image service providers (OSM, MabBox, ESRI 
etc)), and it will often be used in areas with limited connectivity

An extensive web search has identified others who have made similar 
enquiries in the past (in these forums, Stack Overflow etc), and the 
general suggestions for solutions are as follows:

  * ArcGIS Runtime with Qt SDK/Doesn't work for me as down the track I'm
    intending to target an embedded linux device using an ARM processor,
    and ArcGIS doesn't make source available for cross-compilation for
    arbitrary targets. They've recently produced an Android release, but
    nothing for ARM linux in general)/
  * QGIS developer libraries/GPL licence not compatible with my
    commercial development/
  * Use the Qt Location*Map*component with a local tile server or
    offline tile collection,alongside a local tiling engine to create
    the necessary tile set from the input image file. /Seems a bit of a
    hack, as noted I'm primarily using custom maps, as opposed to
    offline copies of public map server images, and my images won't be
    big enough to otherwise warrant tiling anyway/

It would be feasible to develop a Qt Quick component from scratch to do 
this, but given that the existing Qt Location*Map*component provides a 
well defined pre-existing front end interface for everything my map 
would need to do and has an extendable plugin based architecture, 
writing a custom Qt Location GeoServices plugin seems the most sensible 
and elegant way forward.

I've started examining the source code of the existing plugins, but 
can't shake the feeling that in a world containing 8 billion people, 
with "nothing new under the sun", this would have been done already if 
it was a good idea....

Would anyone with more familiarity with the Qt Location module care to 
comment?


thanks

Richard




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