January 2020
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Open Source GIS

Roam for Windows Tablets

IntraMaps Roam is a free and open source app for offline tablet use, providing a field-friendly interface on top of QGIS. On the tablets we tested, we made sure we had enough local device storage, including 4 GB for basemap shapefiles and 80 GB for ECW imagery. Panning, zooming, editing, and taking pictures was extremely smooth and fast. Please see the link below for the GPS receiver we used.

If you’d like to test-drive Roam, Here are a few links to get you started:

Download Roam: Visit the GitHub page for Windows installers.

Read the Docs: Step by step instructions show you how to setup and use Roam.

QGIS: You’ll need to install QGIS on your desktop PC for configuring Roam project files.

QGIS Workshop: If you are new to symbolizing layers with QGIS, this 2014 GIS Day workshop can serve as a quick-start tutorial.

Base Layers ‘Toolkit’: Keeping basemap layers current on offline tablets can be a challenge. This download includes a few scripts, qml style files, and a short ‘readme’ manual to get you started, using free data from our county GIS Data Portal. Simply maintain a master folder for your base layer shapefiles on a shared drive, and let your field staff periodically replace their copies of that folder. The scripts are provided as-is, for public education. Feel free to modify them for your organization’s use.

LARIAC: Most GIS datasets created and/or used by Los Angeles County are available to the public for downloading at no charge. Current high resolution imagery is not one of them. If your organization needs high resolution imagery (including ECW files), current building outlines, and many other benefits, please consider becoming a LARIAC member.

GeoGig: Based on Git (familiar to GitHub users), this versioning utility can synchronize GIS data collected by multiple tablet editors on a file based repository. If your field staff is small, this may be a workable solution for you.

Oslandia: This French open source consulting firm has created utilities for synchronizing with PostGIS databases. This link goes to their GitHub site.

Introduction to PostGIS: If anyone is new to PostGIS, we can all thank Boundless for this excellent free tutorial. Boundless is a U.S. Based company that provides professional technical training and support for open source GIS.

Licensing: QGIS and Roam are released under the GPL. GeoGig is released under the Eclipse license.

XGPS150A Universal Bluetooth GPS Receiver: Most Windows tablets don’t come with GPS chip sets built in. This model was reliable for the price, working in areas where no wireless internet was available. Positioning was within about 15-20 feet of the objects’ locations. Your experience may vary.

A Few More Free and Open Source Tablet Apps

QField for Android: Simply create your style and editing widgets via QGIS on your desktop, then copy your shapefiles, images, QGIS project files, etc. to your Android tablet or phone. This app is field-friendly, easy to set up, and it takes advantage of your offline data and your Android’s GPS.

QField Tutorial – This was a fun activity among a few friends at GIS Day in 2016.

github.com/esri: Esri’s web-centered open source efforts can be found here. Though the company has no out-of-the-box tool comparable to Roam at his time, we’ll leave this link here as a reference.



A Brief Tour of Open Source GIS

Introduction – This series was created as brief overview to provide a path for newcomers to better understand the sometimes confusing world of open source GIS projects.

Part 1: Defining Open – Though almost all open source software is freely available to download and install at no cost, not all open source licenses are the same.

Part 2: GRASS (Geographic Resource Analysis Support System) Developed by the United States military in the early 1980’s, GRASS is the oldest and most powerful desktop application in this series.

Part 3: gvSIG (Generalitat Valenciana, Sistema d’Informació Geogràfica) – With help from the European Union, the software was developed under a contract from the Spanish government.

Part 4: uDig (User-friendly Desktop Internet GIS) – The community that surrounds this software enjoy uDig’s compatibility with open source powered GIS web servers. “If it renders on uDIG, it’ll render on Open Layers”.

Part 5: OpenJUMP (Open Java Unified Mapping Platform) – This open source project is popular among JAVA programmers. Its greatest strengths are its ease of use and well developed drawing tools.

Part 6: QGIS (Formerly “Quantum GIS”) – From its humble beginnings in 2002 as a GIS viewer for Linux, this software is said to have the strongest community support and growth. With a great deal of grass-roots popularity among Linux, Mac and PC users, QGIS is regarded by many as having the greatest combination of functionality and ease of use.

Part 7: GDAL/OGR (Geospatial Data Abstraction and Simple Features Libraries) – These geoprocessing libraries are typically accessed by programs written in C/C++, Python, or the Windows/Mac/Linux Consoles.

Part 8: A Few Notes About Map Projections – Coordinate Reference Systems are a very important part of any GIS project. This article explores online database registries of known coordinate systems.

Part 9: An Open Source Alternative to the File Geodatabase (Sort of) – This topic introduces GIS users to SQLite and SpatiaLite databases.

Part 10: OSGEO, The Organization – The Open Source Geospatial Foundation was created to support the collaborative development of open source geospatial software, and promote its widespread use.

Part 11: Why Learn About Open Source GIS? There are many opinions about the risks and benefits of open source GIS software.


by jh, September 25th, 2012

Using Web Map Service (WMS) layers is a great way to exchange GIS data on the web! Like a child playing with Tinkertoys, all of us can easily assemble maps from free online data sources.

Unfortunately, WMS layers may become unavailable without warning. It’s painful when your GIS software freezes up when your GetCapabilities document isn’t there.

Luckily, mapmatters.org monitors thousands of WMS layers. The site is a valuable resource for testing and searching for new WMS URL’s.



by jh, January 23th, 2012

As GPS-enabled cameras and smart phones continue to be more commonplace, GIS users will see increased requests to create maps from geotagged digital photos. Digital photos contain numerous pieces of information, or tags, that are embedded by digital cameras as pictures are taken. One of the most powerful tools for working with these tags is the free ExifTool by Phil Harvey.

To use ExifTool, download the Windows executable (currently exiftool-8.76.zip) at http://owl.phy.queensu.ca/~phil/exiftool/.

Once extracted, rename the file exiftool(k).exe to just exiftool.exe and place it into a folder where it will be used. (If you plan to use this utility often, consider setting it up in the path.)  Open the Windows Console and navigate to that folder.

Below are some sample Console commands:

exiftool   [Running exiftool by itself prints ExifTool help to the Console screen]

exiftool Photo1.jpg   [This gives you EVERYTHING in the file Photo1.jpg]

exiftool -s Photo1.jpg   [Gives you the same info with actual tag names in stead of descriptive tag names]

exiftool -GPSPosition Photo1.jpg   [Gives you GPS coordinates in that file, e.g. 39 deg 44′ 18.59″ N, 104 deg 59′ 13.39″ W]

exiftool -GPSPosition -n Photo1.jpg   [Gives you coordinates in a numerical format. e.g. 39.7384972222222 -104.987052777778]



In January 2012, this web page was getting a little large and cumbersome to edit. To make room for more entries, some housecleaning needed to be done. To see the LARGE LIST of open source GIS applications that was listed here, please visit http://opensourcegis.org/.