Michael,
GDAL's PDF format page says you can use the GDAL_PDF_DPI config
option...
Best Regards,
Brent Fraser
On 12/13/2011 11:58 AM, Smith, Michael wrote:
I
am trying to convert the historic USGS topo maps
(GeoPDFs) into GeoTIFFs with GDAL 1.8 .
A very straightforward thing to do is
gdal_translate
in.pdf out.tiff
This
works fine but the TIFF looks as if the PDF was exported at
150dpi, which is a pretty crappy resolution. Using
something else (like PDFCreator and printing to a TIFF), the
USGS GeoPDFs can be exported at higher resolutions, but then
of course you lose the georeferencing. So I have GDAL which
keeps the georeferencing but only seems to like 150dpi, and
then a zillion other solutions which allow 300 dpi or 600
dpi, but have no georeferencing.
I
did try gdalwarp -tr 5 5 for example (which would roughly be
equivalent to one of these maps at 300dpi), but it is clear
that it is still rendering the PDF at 150dpi and then
generating a 5-meter TIFF - looks no different really than
the default output with gdal_translate.
Is there some argument that would specify the dpi
at which the GeoPDF were rendered before conversion to
GeoTIFF? I don't see anything like that in the docs or
the list archives.
BTW if you haven't checked out
the historic topos they are great, going back to the 1880s
for Maine. What fun!
My ultimate goal is to have a seamless mosaic WMS
of the old topos for Maine.
*****************
Michael Smith
State GIS Manager, Maine
Office of GIS, Maine OIT
Board Member, Maine
GeoLibrary
Board Member, Maine GIS
Users Group
State Rep, National States
Geographic Information Council
State House
Station 174
264 Civic Center Drive
Augusta, ME 04333-0174
(207) 215-5530
69 o 47' 49.5"W 44 o 20' 54.5"N
_______________________________________________
gdal-dev mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/gdal-dev
|
_______________________________________________
gdal-dev mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/gdal-dev
