Almost a year ago, I posted on Bjorn Sandvik’s Thematic Mapping Engine, which can plot data thematically in Google Earth as:
- Choropleth
- Prism
- Proportional symbol
- Pie chart
At the time, you could only use a limited number of pre-packaged datasets. Bjorn has just announced the Thematic Mapping Engine API, a Javascript library that lets you do thematic mapping in the Google Earth plugin with your own data (including online sources like Google Docs Spreadsheet). Still in beta, and Bjorn is looking for people to try it out (non-commercial use only). Documentation is a bit sparse right now, but if you look at the page source for example maps created with the API, it’s not too hard to figure out.
After yesterday’s post on thematic mapping in Google Maps, John Stewart of the University of North Carolina’s MEASURE program wrote to tell me about their own thematic mapping tool, the E2G Thematic Mapper. This Microsoft Excel macro spreadsheet data and links it with polygon data for countries and their administrative units to create thematic maps for Google Earth:
Image is from the excellent PDF manual included with the distribution. I can’t try it out because I don’t currently have a computer with Excel (2003 or 2007), and it doesn’t seem to run on Open Office Calc.
It also currently only has polygon data for sixteen countries:
- Botswana
- Côte d’Ivoire
- Democratic Republic of the Congo
- Ethiopia
- Guyana
- Haiti
- Kenya
- Mozambique
- Namibia
- Nigeria
- Rwanda
- Tanzania
- Uganda
- Vietnam
- South Africa
- Zambia
But John says that an update coming this summer will add polygon data for more countries, along with more macro features.
If you’re interested in field data acquisition, the entire Monitoring and Evaluation Systems section of the MEASURE site is worth a look.
By default, Google Earth uses latitude/longitude as its coordinate system, with WGS84 as the datum. In the Tools section, you can choose to display lat/long in decimal degrees, degrees/decimal minutes, or degrees/minutes/seconds. You can also set the displayed coordinate system to UTM (Universal Transverse Mercator)/WGS84, a coordinate system often used on maps. But for other coordinate systems and datums in Google Earth, you’re out of luck.
Plex.Mark is a small helper app for Google Earth that, to a limited degree, can show you the position in the center of the Google Earth in many other coordinate systems. After installing and running the program, Google Earth will open up, and the Plex.Mark dashboard will overlay the display, always on top:
Continue reading ‘Google Earth Coordinates In Multiple Projections With Plex.Mark’
MapAction is a non-profit volunteer organization that provides GIS and mapping services to disaster areas. They’ve just published a free 118-page Field Guide To Humanitarian Mapping that’s a terrific introduction to both data acquisition using a GPS, and how to use Google Earth and the free open-source Windows GIS program MapWindow for mapping. I’d even say that it’s a far better choice for beginners than the recently-published GIS For Dummies (more on that soon, when I get the review of that volume done).
Via GIS @ Vassar.
8/13/2009: No longer free; there’s a subscription fee from which a small charge is deducted for every use. A free grid link is still available here for MGRS and UTM.
Earthpoint has a new beta Google Earth function – grid overlays for multiple coordinate systems:
- Deg – Decimal degrees
- DegSec – Degrees, Decimal seconds
- DegSecMin – Degrees, Seconds, Decimal minutes
- Georef – World Geographic Reference System
- UTM/UPS – Universal Transverse Mercator / Universal Polar Stereographic
- MGRS – Military Grid Reference System
Click the button for the desired grid KML file, and open it in Google Earth (UTM here):
As you zoom in, the grids become finer; you may have to wait a bit for the network link to catch up:
Roll your mouse over one of the “balls” defining the grid, and get a pop-up with the coordinates (and UTM zone here):
The crosshair marks the center of the display, the location for which Google Earth shows the coordinates and elevation in the bottom toolbar.
Over at the Google Earth Library site, Matt has started a project to convert USGS topographic maps (1:250K, 1:100K and 1:24K scales) into Google Earth overlays.. These are “super” overlays, where views from higher elevations are at lower resolutions, while closer views load in high-resolution imagery; this speeds up display times significantly. Arizona and Nevada are available now, with Colorado and California coming soon.
The network link to access the overlays online is at the bottom of the web page; click on the “G-Earth” graphic. Once loaded in Google Earth, activate it, then expand it to select the state and map type you want, 1:24K maps for Arizona here:
Continue reading ‘USGS Topographic Map Overlays For Google Earth’
Last week, as part of a post on sample Google Earth plugins apps, I linked to an application called Stereo that generates a stereo image pair of Google Earth views. By crossing your eyes sufficiently to get the two images to blend together, you get a 3D view, possibly accompanied by a headache. Horst Blaesig pointed me to a stand-alone app called Stereo GE Browser that goes one step further – it also can create a 3D anaglyph, a blending of the two views that can be seen in 3D using standard red-blue 3D glasses. Open up the app, and you’ll see three globe views:
Continue reading ‘3D Anaglyph Views In Google Earth’
The Earthpoint Coordinate Converter takes a geographic position in latitude/longitude, or in a number of grid coordinate systems, including:
- UTM
- MGRS/USNG and MGRS Polar
- GeoRef
and converts it to all the other coordinate systems (including lat/long in decimal, DDMM and DDMMSS formats):
(Grid North is the deviation between true north and north along the map projection grid lines)
You also have the option of viewing the point in Google Earth, with a pop-up balloon that includes all the coordinate data:
