[Xastir] Goodbye GeoTIFF, Hello GeoPDF

Fri Jul 6 12:08:12 PDT 2018

Thanks!  I had looked at the help on gdalwarp, but it listed that option as
[-oo NAME=VALUE], which is pretty generic.  I needed to delve further into
the command line options, so you probably saved me a lot of time.  I like
the maps, but they're meant for use when zoomed in quite a bit.  That's
fine, but as is they start to look bad if zoomed in too far as well, so
maybe by increasing dpi I can increase the window of zoom levels where they
look good.

Lee - K5DAT

On Thu, Jul 5, 2018 at 10:12 PM, Tom Russo <russo at bogodyn.org> wrote:

> You an add "-oo 'DPI=600.0'" to the gdalwarp command line to make it
> output at 600DPI.  With the modification for other DPI
>
> I have used a modified version of Xastir's geopdf2gtiff script in some of
> my search-and-rescue GIS work a few years ago, making it send the
> orthoimage,
> topo map, and shaded relief layers to separate files, and to skip the
> "dither down to 8 bit"
> step (because ArcGIS can handle the 24 bit rasters where Xastir can't).
>
> In that script, instead of doing:
>
> -----
> $theGdalWarp="gdalwarp -cutline $inputPDF.vrt -crop_to_cutline -t_srs
> EPSG:4326  $inputPDF $outputTif";
>
> system ($theGdalWarp) == 0 or die "System $theGdalWarp failed: $?";
> -----
>
> the way Xastir's does, I do:
>
> -----
> $theGdalWarp="gdalwarp -cutline $inputPDF.vrt -crop_to_cutline -of GTiff
> -oo 'DPI=250.0' -oo 'LAYERS_OFF=Images,Images.Orthoimage' -dstnodata '5 6
> 7' -co \"COMPRESS=PACKBITS\" $inputPDF $outputTif";
>
> system ($theGdalWarp) == 0 or die "System $theGdalWarp failed: $?";
>
> $theGdalWarp="gdalwarp -cutline $inputPDF.vrt -crop_to_cutline -of GTiff
> -oo 'DPI=600.0' -oo 'LAYERS=Images,Images.Orthoimage' -dstnodata '5 6 7'
> -co \"COMPRESS=PACKBITS\"  $inputPDF Orthos_$outputTif";
>
> system ($theGdalWarp) == 0 or die "Second system $theGdalWarp failed: $?";
>
> $theGdalWarp="gdalwarp -cutline $inputPDF.vrt -crop_to_cutline -of GTiff
> -oo 'DPI=600.0' -oo 'LAYERS=Map_Frame.Terrain.Shaded_Relief' -dstnodata
> '5 6 7' -co \"COMPRESS=PACKBITS\"  $inputPDF ShadedRelief_$outputTif";
>
> system ($theGdalWarp) == 0 or die "Third system $theGdalWarp failed: $?";
> -----
>
> This snippet shouldn't be used as a drop-in replacement for what's in
> Xastir's script, because:
>
>   1) It doesn't warp to WGS84 Lat/Lon coordinates, because I didn't need
>      that in ArcGIS.  It should be obvious how to reinsert that if you
>      look at the actual gdalwarp command lines.  (-t_srs EPSG:4326)
>
>   2) I'm also telling gdalwarp to set regions of no data to
>      the RGB tuple 5,6,7, so that I can tell ArcGIS to ignore those
> pixels.
>      There is no corresponding "ignore pixel of this value" option in
> Xastir's
>      geotiff code, so you could leave the "-dstnodata '5 6 7'" piece off.
>
>   3) I also found in early playing with geopdf2gtiff that compressing the
>      image sometimes made it unreadable by Xastir, which is why Xastir's
>      geopdf2gtiff doesn't do that.  YMMV.  (leave off
>      -co \"COMPRESS=PACKBITS\" if it causes trouble)
>
> On Thu, Jul 05, 2018 at 08:20:10PM -0500, we recorded a bogon-computron
> collision of the <lee.bengston at gmail.com> flavor, containing:
> > On Mon, Mar 21, 2016 at 2:28 PM, Brian Heaton <geekdownrange at gmail.com>
> > wrote:
> >
> > > I cranked the dpi setting in the script so mine would look good at
> higher
> > > zoom levels. Bigger files but storage is cheap.
> > >
> > > ???Resurrecting an old thread here.  I've been converting geopdf's
> lately
> > and found it's easier now to install prerequisites because the current
> > version of the binary gdal package in Ubuntu supports the conversion - no
> > need to build gdal from source.  My laptop is on Ubuntu 17.10, so anyone
> on
> > that release or 18.04 should be able to take advantage.
> >   I'm not sure where the cutoff is, but I do know Ubuntu 16.04 required a
> > source build of gdal because the binary version was below version 1.8.1.
> >
> > I've been looking through the geopdf2gtiff.pl script, but I can't find
> > where to increase the "dpi setting" as the person above indicated had
> been
> > done.  If anyone can shed some light on that (or debunk it if it's not
> > possible), I would appreciate it.
> >
> >
> > Thanks,
> > Lee
> > K5DAT
> >
> >
> > >
> > > >       From: Lee Bengston <lee.bengston at gmail.com>
> > > >  To: Xastir - APRS client software discussion <
> xastir at lists.xastir.org>
> > > >  Sent: Monday, March 21, 2016 10:18 AM
> > > >  Subject: Re: [Xastir] Goodbye GeoTIFF, Hello GeoPDF
> > > >
> > > > Xastir has a script that uses gdal to convert GeoPDF to GeoTIFF.  Tom
> > > Russo
> > > > wrote it a few years ago and refined it much more recently.  There
> was
> > > > quite a bit of discussion about it not too long ago.
> > > >
> > > > Lee - K5DAT
> > > > On Mar 21, 2016 11:12 AM, "Curt Mills" <curt.we7u at gmail.com> wrote:
> > > >
> > > > > As I recall the geoPDF's have multiple layers that can be
> > > > enabled/disabled
> > > > > for viewing. I'm not sure whether these files can be directly used
> > > within
> > > > > other programs w/o having to implement Postscript and a bunch of
> other
> > > > > stuff. Would be worth investigating though.
> > > > >
> > > > > On Mon, Mar 21, 2016 at 7:47 AM, Eric Christensen <
> > > > > eric at christensenplace.us>
> > > > > wrote:
> > > > >
> > > > > > -----BEGIN PGP SIGNED MESSAGE-----
> > > > > > Hash: SHA256
> > > > > >
> > > > > > I recently learned that USGS will no longer release
> GeoTIFF-formatted
> > > > > > map files in favor of GeoPDF[0].  This will likely cause
> problems for
> > > > > > Xastir.  I did locate a instructions for converting the GeoPDF to
> > > > > > GeoTIFF[1].
> > > > > >
> > > > > > [0] http://www.usgs.gov/faq/taxonomy/term/10413
> > > > > > [1] http://www.usgs.gov/faq/node/3704
> > > > > >
> > > > > > - --Eric
> > >
> > _______________________________________________
> > Xastir mailing list
> > Xastir at lists.xastir.org
> > http://xastir.org/mailman/listinfo/xastir
>
> --
> Tom Russo    KM5VY
> Tijeras, NM
>
>  echo "prpv_a'rfg_cnf_har_cvcr" | sed -e 's/_/ /g' | tr [a-m][n-z]
> [n-z][a-m]
>
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