[gdal-dev] Garmin .img data?

Oliver Eichler oliver.eichler at gmx.de
Sat Dec 20 08:01:16 PST 2014


Hi,

The Garmin vector format is well known to a certain extend. Garmin developed it further, but the reverse 
engineering stopped at a point where it was possible to create own maps without any obvious loss of 
functionality. So up to that point the format is known. The document on sf.net is very old and not complete. 
But there is enough open source to learn the details. However the coding of newer maps used by Garmin is 
not known. As long as you stick to maps created by the open source tools that is of no concern.

The format is very complex and has many very proprietary features, that are hard to handle in a multi-
purpose library like GDAL. I don't think I would want to use GDAL as a replacement for my own render code, 
because it would not give me the API I need. With raster maps it's different. I really appreciate GDAL for 
that. However raster maps do not have single elements you want to search for, nor routing information or 
the need of skin files.

So from my point of view I do not see a real benefit in GDAL supporting Garmin's proprietary format. It's a 
lot of work to implement and in the end you do not get 100% of what you want. Scientifically the nutritional 
value of those maps is against zero. You better use the raw data in that case.


just my 2 cents

Oliver




> Hi Even,
> 
> Il 19/12/2014 17:01, Even Rouault ha scritto:
> > Probably perhaps nobody has written it. The link you gave doesn't
> > link much information about the format. Is it the vector format
> > described at http://sourceforge.net/projects/garmin-> > img/?source=typ_redirect ? If so, a quick skimming of it would lend
> > me thinking that read support should be possible, although likely
> > not a trivial effort (41 pages for an unformal specification is
> > quite significant). Write support and interoperability with Garmin
> > devices would probably be harder as I can see quite a few ??? in
> > the document.
> 
> thanks for your reply. I imagined this, but I was surprised by the
> fact that apparently small projects were able to read the format
> without much difficulty.
> Going to ask qmapshack dev.
> All the best.
> --
> Paolo Cavallini - www.faunalia.eu
> QGIS & PostGIS courses: http://www.faunalia.eu/training.html
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