[poppler] Extracting geolocation metadata from a GeoPDF file

[Albert Astals Cid]

A Divendres, 26 de març de 2010, Phil Endecott va escriure:
> Dear Experts,
> 
> I need to extract the geolocation metadata from a GeoPDF file.
> 
> If you're not familiar with this format, it's something that was
> developed by a company called TerraGo Technologies and was adopted as a
> "best practice" by the Open Geospatial Consortium.  There is a document
> describing it via http://www.opengeospatial.org/standards/bp (look for
> "GeoPDF"; click-through but free-looking license required).  Basically
> it provides a method to associate positions in the document with
> latitude-longitude positions on the ground.
> 
> The method used is to define "map frames" that are added to the parent
> PDF page object.  As I understand it, there is a new key 'LGIDict' in
> the page object, which is an array of dictionaries one per map frame,
> each of which contains a set of entries like containing matrices,
> bounding boxes etc. that define the geolocation for that frame.
> 
> My hope is that it would be possible to write a small program that
> would open the PDF file and iterate through the pages, dumping this
> data as it is found.  I have had a look at the pdfinfo program which
> seems to be doing something similar for other metadata.
> 
> Would anyone be able to help me with this?  

Don't really count on that, if you want this done, doing it yourself is safest 
bet to get it done.

> I am a competent C++ coder
> but have never had to understand much about how PDF works.  Is starting
> with pdfinfo sane? 

Yeah as good as any other thing

> How do I access the page objects?  Is there a way
> to iterate through the entries in a dictionary?

You haven't looked at the code right, because it's quite straighforward.

> 
> Or, maybe there is already some other tool that will do this?

Not that i know

> 
> Here's an example of a GeoPDF file: 
> ftp://ftp2.cits.rncan.gc.ca/pub/cantopo/50k_pdf/092/g/cantopo_092g06_pdf.z
> ip
> 
> 
> Many thanks for any advice.

Good luck!

Albert

> 
> 
> Regards,  Phil.
> 
> 
> 
> 
> _______________________________________________
> poppler mailing list
> poppler at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/poppler