Free Five Course Series on QGIS Starts Soon

Del Mar College is offering a free online course that gives an introduction to GIS and QGIS.  The course is titled "Introduction to Geospatial Technology Using QGIS" and is available from the Canvas Network.  The five-week course is self-paced and runs from February 23rd to March 27th. Already 1,000 students are signed up. The courses were created with funds from the National Science Foundation (NSF) and US Department of Labor.

It is great to see a course geared towards QGIS!  The course hits on components of the core competencies for entry level geospatial occupations as outlined here.  It includes lectures and hands-on exercises.  If you can't wait or can't find time, the course materials for this course and others are available at GitHub: https://github.com/FOSS4GAcademy.

From the OSGeo listserve, this course is part of a larger effort to educate about GIS and FOSS GIS called "Geo For All" and GeoAcademy.  This is the first course in a sequence of five, so more courses will be on the way!

The other four courses are:

• Spatial Analysis Using QGIS
• Data Acquisition and Management Using QGIS
• Cartography Using QGIS
• Remote Sensing Using QGIS

If you know someone who is interested in GIS or QGIS and likes independent study, it looks like a solid opportunity!  

For more information: https://www.canvas.net/browse/delmarcollege/courses/cn-1681-intro-qgis

Course offerings from Penn State University (PSU) and Coursera: 

http://opensourcegisblog.blogspot.com/2014/08/free-online-mapping-classes-from-psu.html

An Introduction to Leaflet, Part III: Comparing Heatmap Plugins

A great advantage and disadvantage of free and open source GIS (FOSS GIS) is the variety of options out there.  In this post, we will take a look at four different heatmap plugins for Leaflet.  If you want to skip to the final product, visit: http://webmapexamples.net/leaflet/heatmap/heatcompare.html
to see the final comparison.

We will take a look at four different plugins listed on Leaflet's plugin page:

• Heatmap.js
• HeatCanvas
• Leaflet-div-heatmap
• WebGL Heatmap

Screenshot of the comparison site: http://webmapexamples.net/leaflet/heatmap/heatcompare.html

Data
I used QGIS to generate 500 random points within the state of New Hampshire.

Each plugin references point data and intensity/weight values in slightly different way.  For the three plugins I got to work, here are how points should be formatted.

• Heatmap.js: [{lat: , lng: , count: },...
• HeatCanvas: [0,0, 1] point at 0,0 with count 1
• Leaflet-div-heatmap: [{lat: , long: , value: },...
• WebGL Heatmap: N/A

Overall Impressions

Performance: Heatmap.js was fastest. (Although I did not have a chance to use WebGL Heatmap.  HeatCanvas was slowest rendering.

Ease of Use: Heatmap.js was the clear winner! Leaflet-div-heatmap required more knowledge of JavaScript and I ended up editing the actual plugin code.  WebGL required understanding that!

Documentation: Heatmap.js and HeatCanvas were good.  For Heatmap js be sure to visit the website separate from github.  Leaflet-div-heatmap had poor documentation.

Other considerations: I couldn't quite get the WebGL plugin to work - when adding point data. However, I was able to get a demo working and be able to interactively change density using my mouse with another *.html file.  However, WebGL does boast performance for large datasets, so I may return to it a later date.  The Leaflet-div-heatmap uses sort of collect events/morph feature, so it is different from the rest, be sure to zoom in on the map.  This will become clearer when you try it... Also don't forget to check out each plugin and their array of options!

Heatmap Comparison webpage:
http://webmapexamples.net/leaflet/heatmap/heatcompare.html

See also:
Leaflet.heat
SimpleHeat
Leanpub: Leaflet Tips and Tricks
A related post in Stackoverflow