[gdal-dev] extract vector/raster data from GeoPDF

Joaquim Luis jluis at ualg.pt
Thu Sep 3 11:40:12 EDT 2009

Brent Fraser wrote:
> Joaquim,
>   Interesting! As Peter pointed out, the LPTS tag is the transformation 
> matrix to go from projected coords to page coords, and is created by 
> forming the UTM->page coordinates tranformation (from the information in 
> the CTM tag below) and inverting it (there's a brief mention near the 
> end of 
> http://geopdf.blogspot.com/2009/02/georegistration-worked-example.html)
>   Since the TerraGo way has been superceded by the Adobe/ISO way (thank 
> goodness!), it makes it easier to identify the reference system 
> definition in GDAL, so there may be some hope for GDAL and GeoPDF.

>   Now I need to think about my requirements for reading and writing 
> GeoPDFs. Write a Postscript driver for GDAL?   Figure out how to write 
> the equivalent info into a PDF using Mapserver/Cairo?  Yikes!


I am on this list more to keep learning (as the present case) than as a
core GDAL user (but I use GDAL a lot in Mirone). In fact I am much more
a GMT user where I also do some development. I mentioned it before here
but probably it slipped away, the GMT program ps2raster can write world files
and create GeoTIFFs (from system calls to GDAL) from postscript files
created by GMT.
I think that it wouldn't be very hard to extend ps2raster's ability to
write GeoPDFs if, as I said before, there was a way to get a WKT from a
-J... GMT syntax.
Anyway, it wouldn't be a GDAL solution and a write-only one so I don't
know what else to tell you.


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