How To Plot A Coordinate Dataset In Google Maps [Aardvarchaeology]

How To Plot A Coordinate Dataset In Google Maps [Aardvarchaeology]

via ScienceBlogs Select by Martin R none@example.com on 12/14/11

As an archaeologist I often need to plot coordinates on maps and plans. At every scale, really: from individual finds on the plan of an excavation trench to the distribution of something across Europe. Just dots of varying shapes and colours on various background maps. Most often, it's GPS data from field walking and metal detecting. My colleagues in contract archaeology and academe use ArcInfo for these things, but I've never had incentive or opportunity to learn to use it. Also, once you know the software, you still need a map to plot stuff on, and those are expensive. So I've been wondering if I could somehow plot my coordinate data via Google Docs in Google Maps. Free software, free maps, free updated aerial photographs.
Turns out, you can. And today I figured out how. I believe it was David Petts who nudged me in the direction of Google's "Fusion Tables". And Hans Persson (who is an inveterate geocacher) asked me to write my findings up on Aard.
1. Data formatting
Convert your coordinate data to decimal lat & long after the WGS84 datum and with a decimal dot, not the Swedish decimal comma. For instance, my house is at lat 59.289576 long 18.258234. Call the northings column "Latitude" and the eastings column "Longitude". (There are Excel macros to do coordinate conversions. For the Swedish systems, I find Robert Larsson's on-line conversion utility handy, though it doesn't do batch jobs.)
You may also want to add a "Text" column to describe what each point marks, and an "Icon" column that takes entries like "small_red" and "large_blue".
(The Map function is pretty smart and also happily works with street addresses or place names if you put them in a "Location" column.)
2. Where to put the data
Stick this data into a spreadsheet in Google Docs. Save and close the spreadsheet.
3. Plot your dots
Now click the Create button on the start page of Docs and select "Table (beta)". Tell the software to grab the data from the Docs spreadsheet you just created. (At this stage you can also tell it to disregard any extraneous data columns.) I don't quite know how to conceptualise the distinction between these tables and standard Docs spreadsheets. But for practical purposes, tables are useful because (unlike spreadsheets) they have a Visualize menu including a Map alternative. Use it and zoom in on your area of interest.
4. Colour your dots
At first, all of your dots will be small and red. To get the software to use the data you entered into the "Icon" column, (such as "large_blue"), click "Configure styles", change the "Marker icon" settings to "Column", and select "Icon".
Tell me how you're doing with this, Dear Reader, and I'll update the entry as I learn more. The first thing I want to find out now is how to create a dynamic link between my spreadsheet and the map, so that any changes to the data appear automatically on my maps. At the moment I have to make a new table every time I change the spreadsheet. Also, the only way I currently know of to get maps out of the software is screen grab, which doesn't make for great resolution.