Making Maps with 'Google My Maps', Part II

Now we will look at more features, performance, and wrap up with some strengths and limitations of My Maps.  If you missed the first post, you can check it out here!

Symbology/Icons
Google includes a set of stock symbols that can be added to your map. Clicking on a category in a layer will bring up the option to change the marker color as well as add different icons.  Google has a nice stock selection of icons for: business, crisis, facilities and services, points of interest, recreation, and transportation.

Google has a nice set of stock icons.

You can also add custom icons at the bottom of this pop-up by linking to an image's web address.

Polygons in KML
Adding polygons will slow down your maps performance, currently, when they are clicked the polygon also shows the points that make it up--a strange sight--compared to other web publishing platforms.

Labeling
You can add labels by clicking the style paint brush, but your map will also take a performance hit. However, even with lots of labels, performance remains very respectable.

Adding labels will decrease the performance of your map.

Set Default View/Extent
Click the three vertical dots on the "Add Layer" menu (not the individual layer), and you will see the option to set and confirm and default view/extent, you can zoom in/out and pan and click this to set it.

Setting a good default view can significantly increase your map's appeal.

Limitations
Google has a nice table of file limits at: https://support.google.com/mymaps/answer/3370982?hl=en. Maps are limited to 10 layers, 10,000 features per map (2,000 per layer), maximum of 50 attribute columns, 5 MB for KML/KMZ, and 2,000 rows/points and up to 40 MB for other file types.

Google's clearly lists the limits for data uploads.

Interestingly, maps can be printed in HD up to 4K resolution. The ultra-high definition revolution is upon us!

Conclusion
Google has developed a nice user friendly interface to allow anyone (even non-mappers) to create free interactive maps. Very cool!!  It will be interesting to see how much My Maps is developed/improved, how quickly/slowly, or whether it stays the same.

Making Maps with 'Google My Maps', Part I

Google may be moving away from making software, like Google Earth desktop--the Pro version was made free--but they still have a few tricks up their sleeve.  Recently, Google made a solid entry into the web publishing domain by giving users the tools to create more sophisticated online maps.  Gone are the days of just adding placemarkers, and now users can add spreadsheets (automatically geocoded) and *.kml files.

As of mid-summer, users can now create and manage their own maps via Google Drive, called "Google My Maps" or simply "My Maps."  All you need to do is setup a free Google Drive account, click on "My Drive" at the top, then "New File", and "Google My Maps"

Google created a very user friendly way for users to make online maps from Google Drive.

There are nine different basemaps to choose from.  Adding layers is easy.  Simply, click the link "Import" to add data or "Add Layer" to add additional layers on top or below.  You can add *.csv, *.xlsx, or *.kml files.  You can directly import files by searching your Drive or import them from your desktop.  If you use a spreadsheet, Google will prompt you to identify the location field or field(s) whether an address or placename as well as how to identify/name your features.

In this example, we will look at a spreadsheet of Substance Abuse Clinics (2011) from the City of Chicago of Data Portal.  After clicking "Import, we are asked to select the location field(s). It can handle addresses in a single or multiple fields.  Next, you will be asked what name/title for your places should be.

If Google has problems geocoding a spreadsheet, you will receive a warning.

Next, we will symbolize the markers by "Population Served" or age groups that each clinic serves. You can also change the symbols for each class.

Google allows map creators to make changes to symbology.

At this point, you will probably start to think about saving your project...But, Google has you covered as changes are saved as you go along.  Be sure to give your map a good name, so it does not get lost among your other files.

You can even add a widget for people to get directions.

 Maps can be shared and permissions set with a few clicks after pressing the share button.

What the map looks like so far.  Clicking on markers brings up attribute data.

You can check out the interactive version at: https://goo.gl/39D8lG using your desktop computer or mobile device. Next post, we will look at more features, performance, and wrap up with some strengths and limitations of My Maps. 

SaTScan 9.4 released, better than ever!

SaTScan is a program for detecting clusters over space, time, and space-time.  It is available for Windows, Mac OS X, and Linux. SaTScan 9.4 was recently released and it is better than ever!  The data import wizard now allows shapefiles to be read and and a graphing feature has been added to help examine temporal trends. Visit the link for a better look at the rundown of new features.

The Import Wizard now reads shapefiles.

In previous posts, I've covered the types of files you will need and how to aggregate data in preparation for importing it. Since version 9.2, SaTScan has had the ability to export *.kml and *.shp so that the most likely clusters can be viewed in GIS software. (Aside: Google Earth Pro is now free! https://www.google.com/work/mapsearth/products/earthpro.html)

Below is an example looking at clusters of low immunization rates in California from the journal Pediatrics. Free full-text: http://pediatrics.aappublications.org/content/135/2/280.full.pdf+html

In SaTScan, using lat/long coordinates, allows users to export to *.kml and *.shp.
Google Earth opens the *.kml automatically when a run is complete.

A few tutorials are being made, http://www.satscan.org/tutorials.html and sample data is available. Be sure to read the expertly written user's guide before running: http://goo.gl/rHg7M6. and the long and varied bibliography of analyses conducted with SaTScan: http://www.satscan.org/references.html

Update #1 (2/20/15)
Scan statistics can also be implemented in R's Spatial Epi Package and rsatscan.

More 3D Maps and Tips Using QGIS2threejs

After last week's popular post, here are few more maps and tips using the QGIS2threejs plugin.

The Maps

1. 3D Chloropleth Map of Crime Counts by Police Beats in Chicago, 2013
2. Visualization of Mt. Rainier, Seattle
3. Groundwater Depths in Three Counties in Nevada

Data sources and references:
Open Data Chicago
Chicago: Official Police Maps (CLEARMAP)
National Map Viewer
Nevada Bureau of Mines and Geology

When viewing the maps, if a black box appears instead of a basemap, try refreshing/reloading your browser and the basemap should display properly.

The Tips

3D Chloropleth Map:  Here is a trick to create a 3D chloropleth map on a flat surface.  The plugin won't run without a digital elevation model (or DEM) raster, but you can 'trick' it into using a flat raster.

• Updated(12/9/2015): The plugin now allows users to select a flat surface/no DEM used
• Take the raster calculator and exponentiate/raise all cell values to the power of 0 (rastervariable^0). The resulting raster will be flat with a value of 1.  Alternatively, multiply by zero.  (You may also have to symbolize null values as well.)
• Classify and symbolize the polygons using your desired color scheme--before using the plugin
• In addition, I changed the color of the raster file in QGIS to match the background in the *.html file (#ccccff). 
• I added HTML code for a basic legend using frames (90% for the map, 10% for the legend)

Basic HTML code sourcing the two frames.  The "Chicago" frame was generated from QGIS.
The "Legend" frame was a simple piece of code directed to a JPG of the Legend.

Screenshot of the final map and legend.

Mt Rainier:  Instead of using a web service, I download imagery and used the Build Virtual Raster in QGIS.   I used a detailed DEM and imagery from the USGS's National Map Viewer.  You can download files from USGS by using a bounding box, for example.  I used a vertical exaggeration of 1.1 in the plugin.  Click the screenshot below to enlarge a comparison of between Google Earth and the plugin's version of Mt. Rainier.

Left: Google Earth, Right: Plugin result using files from USGS

3D Groundwater Depths / Underground:  Using point data with depths, you can either select a negative multiplier in the plugin or create a new variable and multiply your depths by -1.

If your depths are positive values, select a negative multiplier in the plugin.

An overhead and underground view of the map.
The orange boundary represents three counties of interest.