We’re starting out with Google Earth for our GIS (Geographic Information Systems) platform, though hopefully in the future we’ll add others. So, if you don’t already have it on your computer, the first thing to do is install it. Go to earth.google.com, click on “Earth Pro on Desktop,” and then hit the Download tab at bottom left of the screen. The program knows if you’re working on a PC, Max or Linux.
There’s a “Help” menu on Google Earth that goes into great detail on how to use it, but here’s a quick summary.
When the Google Earth (or Google Earth Pro) opens, you’ve got a map that takes up most of the screen, and then running down the left-hand side is a sort of Table of Contents.
Let’s take the Table of Contents first. It’s in three parts: top left is a Search box; middle left is a Places box (which should be mostly empty if you’re just downloading this), and bottom left in the Layers box is a set of “primary database” layers. For our purposes at this point, you only need three of these “basic Layers” turned on: 1) “Borders and Labels,” 2) “Photos,” and 3) “Terrain.” So click on the boxes to the left of those titles, and unclick any others that may be turned on. Then try out the “Search” box. Type in your home address, and either hit “Enter” on the computer or the “Search” button at right: this should “fly” you to the site, and give you an idea of the accuracy (or not) of the whole program.
Now let’s look briefly at the map part of the screen, the right-hand three-quarters or more of the screen.
- Taking up most of the screen is the globe of earth suspended in black, starry space.
- At bottom right you’ll see two sets of numbers: the latitude and longitude of the cursor (run your cursor around the globe to see these latitude-longitude numbers change), and the apparent eye altitude of the observer (which starts out way out there, 12,000 miles and more; we’ll change that figure in a minute).
- Along the top left above starry space is a set of tool icons we’ll talk about later.
- And then, at top right, are navigation tools, which is the next thing we need to talk about.
Navigation tools at top right – they light up when you mouse across them:
- The slide bar at bottom zooms you in and out of the view. You can either left-click and grab onto the minus sign in the middle of the bar, and slide it up and down to zoom in and out, or you can click on the plus at top or minus at bottom and manipulate it that way. Try it out.
- To navigate N-E-S-W on the Google Earth screen, use the disc directly above the slide bar. Zoom down to where North America fills the screen (with the slide bar), and then try clicking on the circle. The closer to the edge you click, the faster you will move.
- Lastly, at the top of the Navigation Tools is a slightly bigger disc, surrounded by a circle with an N on it (for North). You can click and drag the outer circle around to make the screen face any heading on the compass. Clicking once on the “N” restores the screen to the conventional “north up” view. The inner disc changes your view from straight down onto the earth’s surface to an angled one. Clicking on the top of the disc gradually changes your view from straight down to angled, though unfortunately there’s no central point that is kept through all this. You have to angle the view a little, then click and drag the N-E-S-W disc below to get the earth’s surface in view again, and so on.
Mouse Navigation. The kind of navigation described above under heading 3) works, but it’s fairly cumbersome and slow. But with a simple mouse you can navigate around the Google Earth map screen about five times as fast! To zoom in and out of the screen, just use the roller button on your mouse. To navigate N-E-S-W, just left-click and grab the screen, pull it to one side, release and grab it and pull it again. And neatest of all (to do this first zoom down to the Rocky Mountains in Colorado until you’re about 10 miles or 50,000 feet apparent eye altitude), to flatten the view all you do is depress the roller button on the mouse, and with the roller button still depressed, pull the mouse toward you. The screen should tilt, still focused on the point under your mouse when you started, giving you a wonderful 3-D view of things. Then, roller button still depressed, push the mouse away from you to restore straight down view. Finally, try circling the mouse; you should be able to turn it into a real joystick.
Finally, in this section on the basic Google Earth screen, let’s talk about a couple of the simplest and most useful tools in that bar over the top left of the map screen.
- Clicking on the measure tool (ruler icon) gives you the ability to measure a simple straight line, a path, an area, etc. The default setting when you open it up is simple straight line, so click on one place on the earth’s surface, then another, and the total length comes up in the “map length” box. I’ve found this to be really, really helpful in understanding distances and relationships.
- Secondly, there is the “historical imagery” tool (which looks like a clock with a green arrow draped over it). “Search” your home address again, and when you have been “flown” there, turn on the historical imagery tool and click leftwards (back in time) along the bar that shows up. You should be able to see changes in the neighborhood from when Google Earth first began accumulating aerial photographs of the terrain (in the U.S. this would mostly likely be in the 1990s).
This website has a Google Earth folder for each book chapter. Here’s the short course in how to use such an existing Google Earth folder (.kmz file).
To start with, Google Earth is basically a mosaic of aerial photographs of the earth’s surface draped over a 3D grid that models the ups and downs of the land. Originally it was called “keyhole markup language,” or .kml, and the compressed version became “keyhole markup zip,” which is where you get the .kmz suffix. At any rate, these are basic computer files that you can store just the way you would any other computer file.
When you click on the appropriate .kmz file, it should open in the Places box of your “Table of Contents,” down under the “Temporary” label. All you need to do to save it to your Google Earth account (from the same computer), is to click on an drag it above the Temporary label, or to right-click on the folder title and choose “Save to My Places.” That way, every time you open Google Earth from that same computer, it will automatically be in your Places file. To save it someplace on your computer – which I highly recommend – right-click on the folder title and click on “Save Place As,” and then tell the computer where you want it saved.
Now you typically work from left to right in using the Google Earth folder.
- Click on the down-facing arrow at far left of folder title to open the folder.
- Click in the little square box at left of first layer to turn it on.
- Double-left-click on the icon (a pushpin icon for a Placemark, or a point on the map; 3 dots connected by a line for a Path, or a line; or a little hexagon icon to represent a Polygon, or an area). Then Google Earth will “fly” you to a pre-set framed view of the location.
- If the layer title is blue, that means something is embedded in it – explanatory text, website, etc. – so click on the blue layer title and read text and generally follow instructions.
If the main map screen should get so cluttered with icons and other things that it’s confusing, go back and turn off the offending layers by unclicking in those little left-side square boxes.
The Path layers are especially interesting. Any Path you can “fly” (over the Google Earth surface) at height, speed and camera angle of your choice. And you can also “Show Elevation Profile” of any Path, and by running your cursor along the graph of elevation that comes up, follow a red arrow on the map tracing the Path along the Google Earth surface.
For someone raised on paper maps, as I was, it’s all some kind of magic. In terms of my own modern world history textbook, Fairy Tales, Patriotism and the Nation-State, for example, I’d estimate that 30% of the value of the whole is in the visual GIS folders that parallel the chapters.