GoogleEarth

First impression, written shortly after GE release

I looked at GoogleEarth and yawned, I must be jaded. Since then many people have told me how great it is, did I miss something? Maybe it was the 300 hours I have already spent working with ESRI 3D Analyst?

Okay, so it was the only session at NWGIS that was packed. Okay, so I will look at it again. The presenter there from Pierce County has managed to have fun with it so maybe I can too.

To me what's cool about it is that it streams both the DEM and raster photo data from a server so that everything appears seamless; I don't have to locate and download the layers and then load them into my own ArcScene project. I wish that Hawaii would break down and have some high res photos done. I am getting tired of these LandSat images.

What the Pierce county guy did was overlay his own data on the GoogleEarth maps. He did that by writing his own KML files. GoogleEarth used to be Keyhole so the language it's based on is called KML which is (what else) an XML variant.

Link to KML documentation at Keyhole site

What can I do with it

I can add a raster layer to the map using GroundOverlay. The raster is referenced with an href tag; it can be anywhere (URI) or it can be a file on the local network.

I can add PlaceMarks to the map.

I can draw points, lines, and polygons onto the map.

I can put a text overlay layer onto the map

I am thinking that I should be able to insert the locations of all the CDS Wireless GPS receivers onto a GoogleEarth map...

Coordinates have to be in lat-lon-alt format. They can't be in projected coords. Drat.

SOOOOOOOOOO

I want to take a shapefile from the Corvallis collection, convert it to unprojected WGS1984 UTM zone 10 data using the ArcToolbox, extract vertices from it, and convert them to a KML file. As Dr. Tim Righetti would say, "What are you waiting for?! You know what to do."

I found a VB script in Arcscripts called "Export to KML". It works great. It is an ArcMap extension that does the shapefile to KML conversion. The datum for our NAD27 files is wrong, so output is wrong for GoogleEarth -- you have to convert first to WGS84. But wait! There are more scripts. "KML Home Companion" purports to handle re-projection. Well, it does not do any better than "Export to KML". It does have color and transparency controls, but generating a KML polygon from a circle makes a lumpy thing where as the proper shape is retained in "Export to KML" so I think I will stick with it for now.

The ultimate cool tool is allegedly in beta testing: Brian Flood's Arc2Earth I like how his example puts the attributes into a pop up.

Sample of KML

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.0">
<Placemark>
 <name>725 Farmers Lane, Santa Rosa, CA</name>
 <open>1</open>
 <address>725 Farmers Ln, Santa Rosa, CA 95405, USA</address>
 <styleUrl>root://styleMaps#default+nicon=0x304+hicon=0x314</styleUrl>
 <Point>
   <coordinates>-122.687567,38.442873,0</coordinates>
 </Point>
</Placemark>
</kml>

Links to Google Earth places

The place to learn about the software formerly known as Keyhole is at the Google Earth Community forums. It's also accessible directly from GoogleEarth...

Global Connection is a project to tie National Geographic data to GoogleEarth.