I needed to convert GeoPDF files to GeoTIFF. I'm not command-line savvy. So I was hesitant to try this. When the gdal_translate command failed no matter what I tried, I nearly gave up. (I can just screen-shot the PDFs. Right!)
But I kept digging. I found that not all GDAL installs support PDF. I had to get a specific set of GDAL binaries for Windows. Here's how and why:
I'm doing volunteer/non-profit work to publish map services that show georeferenced map layers for historic maps of Caroline County, Maryland. I'm using MapTiler, Tileserver, QGIS, and ArcGIS Online for low-cost production and publishing. Recent products are:
- 1875 and 1897 county and towns via AGOL and
- 1897 county in OpenLayers.
Next task is to publish similar services and maps from the USGS Topo GeoPDFs. I need to convert the GeoPDFs to GeoTIFF in order to publish the tiles as a service. (Esri has done this already. But only for paying customers.)
I found a tutorial for using GDAL's gdaltranslate utility. After installing GDAL and cursing my way through the godawful Windows command line window, I kept getting GDAL errors. GDAL wasn't recognizing the PDF format.
Why not? I was following the tutorial steps exactly. I checked forums and found that GDAL has PDF support in some releases but not in others -- it was working for Ubuntu installs, but not for all Windows installs. The tutorial used the Ubuntu installer. I had used the OSGeo4W installer for GDAL. That one does not include PDF support. Gotta love opensource.
I found a pointer to GDAL binaries I needed at gisinternals.com. I downloaded the zipfile with the files that are right for my Windows system. Simply unzipped the file in a folder. Then ran the SDKShell.bat file. No need to install anything. That worked for me. Gotta love opensource.
Saturday, June 28, 2014
Friday, January 3, 2014
But worry not, GIS worker: Spatial might no longer be special, but projections, datums, and legacy file formats will continue to be very, very special.
- Brian Timoney, MapBrief
Okay... GIS is not sexy like your iPhone locator app. But it will always be special. In the same way that your plumbing and electrical and HVAC systems are special. Next time they stop working, ask yourself just how special they are. Next time your iPhone map is missing Main Street, ask yourself how special GIS is.
Consumer and business geo apps and services keep evolving - cutting edge today and obsolete tomorrow. BigData today - legacy file format tomorrow. But projections, datums, and georeferencing will always be there to provide ground truth.
Esri and the ArcGIS platform have been around for 30 years, defining and documenting GIS work. So when we needed to understand what GIS workers are doing across a variety of industries, we looked at the list of tools in ArcGIS Toolbox as a compendium of GIS workflow and process skills.
We needed the ArcToolbox list itself as a data set -- not a PDF poster or searchable web site. I asked Esri for an ArcToolbox list as Excel table or other word processing format, but they could not provide. So my friend at Esri, Nick Toscano, and I compiled the table ourselves. That's almost 900 "GIS tools" in an Excel data table. Easy to sort, filter, annotate, categorize in ways that meet our needs.
Here it is.
Some of the tools are pretty arcane. But most are plain markers for the nuts-and-bolts work of GIS professionals in towns, cities, and counties who have to deal with projections, datums, and legacy file formats every day. Not the next wave or next-big-thing. Just the actual data and task at hand.
How will we use this?
- Survey and assess the experience of our GIS workers.
- Plan GIS skills training and investment.
- Design new workflows to make common tasks more efficient.
- As a quicker reference for building geoprocessing services.