On Tue, Dec 13, 2011 at 2:13 PM, Derrick Brashear <[email protected]>wrote:
> From my mail to geowankers:
>
>
> gdalinfo $i|grep NEATLINE | awk -F= '{print "foo,WKT\nbla,\"" $2 "\""}' >
> $i.csv;
> gdalwarp -crop_to_cutline -cutline $i.csv -co "GDAL_PDF_DPI=250" -of
> GTiff $i $i.tiff
>
>
> On Tue, Dec 13, 2011 at 1:58 PM, Smith, Michael
> <[email protected]>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
>>
>>
>
Oh, and you want 1.8.1 for -crop_to_cutline
none of this is needed if you're not tiling; this is just the extras to
crop to the neatline. otherwise, the GDAL_PDF_DPI=250 (which is the native
scanning resolution per the usgs)
is the relevant bit.
> 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
>>
>> [image: icons]
>>
>> 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
>>
>>
>>
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>>
>
>
>
> --
> Derrick
>
--
Derrick
<<icons_tiny.jpg>>
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