I am trying to extract point data from a non-geo-referenced vector PDF file, to import into QGIS/ArcGIS. You can download a copy of the PDF file here, if interested, but I've tried to include screenshots of the relevant parts to make that unnecessary since it's such a large file (~171 MB).
The PDF file is a map of mineral resources in Afghanistan, which looks like this:
Here is a closeup image of a small segment of the map -- notice that it contains a bunch of labeled locations (cities/provinces, etc), colored regions (representing geological/rock types), and point data with different colored/shaped icons (representing known mineral/petroleum deposits):
I am primarily interested in extracting the locations of the little icons representing the geo-locations of mineral/petroleum deposits, and using them to generate point data that I can import into QGIS. That is, for all of the icons listed in the legend below, I want to find any instances on the map and create a table that has their x,y location and "category" field that matches the categories listed in the legend:
In the bottom left corner there is the following information about the projection which I feel could somehow be used to map from (x,y) coordinates in the PDF file to (x,y) coordinates in WGS84:
Obviously, if there is an easy way for me to do this in QGIS, I'd love to know about it ... but from my searches so far, it's appears likely that I'm going to have to write code to extract the data from the PDF ...
If that is the case, then I would be interested in Python/C/C++/Scheme libraries that could be used to extract the information I described above. And if no libraries exist that can do this easily, then please share ideas about resources/techniques that might help me code my own solution for this.
Any ideas on how to tackle this problem would be useful, even if they only solve some small part of it ...
So I've experimented a bit with a FOSS tool called pstoedit which can extract some of the data from the PDF file and convert it into a DXF file (a common CAD format that QGIS can work with). I used the DXF with splines format option (pstoedit -f dxfs infile.pdf outfile.dxf) to convert the file, and got a DXF file that QGIS was able to import using WSG84 (I still haven't figured out how to use the projection/reference info in the bottom left of the map to overlay this point data, in the right locations, over my base map of Afghanistan).
However, there is very little organization to this data - it's just (x,y) data and generic Text field names like "Text" or "EntityHandle" (see left sidebar in image below). And as user30184 pointed out in their answer, all of the data is jumbled together in one Layer (0). So there is no clear way for me to associate the graphical icons with the individual text labels (mineral deposit categories) from the legend. Here is what it looks like so far - I'll post more if I make more progress: