Google Earth 101 - Using the Image Overlay Tool in Google Earth
Written by Eric Pimpler, President, GeoSpatial Training Services, LLC
13 August 2007
In this article you will learn how to use the image overlay functionality provided in Google Earth to import existing images into the 3D display and drape them over the existing terrain. Many image file formats can be displayed in Google Earth including jpg, bmp, gif, tiff, tga, png, and a number of others.
What this means is that you can import USGS topographic quadrangles, enhanced aerial photography and/or remotely sensed images, historical maps, raster image files exported from ArcGIS and other GIS software, and many others. Google Earth provides the capability to easily accomplish this task.
1. Open Google Earth 4 and enter Monticello, UT in the Fly To tab on the Search panel. Zoom to this area.
2. Click the “Add Image Overlay” Button
The Add Image Overlay dialog box will appear along with hash marks on the GE display that can be used to move and stretch your image.
3. Give your image overlay a name (Abajo Peak) and click the Browse button. Navigate to the image file that you downloaded (AbajoPeak.tiff) from geospatialtraining.com.
Your display should now look similar to the image below. This .tiff image is a USGS quadrangle topographic map for Abajo Peak in Utah. You’ll notice immediately that this particular image has not been georeferenced. It is simply displayed in whatever area you happen to have navigated to in Google Earth. Next, we’ll georeference our image.
4. Click the Location tab and then use a combination of dragging the green markers around the image along with manually entering the coordinates until your North, South, East, and West coordinates appear similar to the figure below. Now, I should point out here that I’m providing the coordinates for this particular image. You will need to know the bounding coordinates for each image that you import into Google Earth so that you can correctly georeference the image.
5. We will leave the items on the View, Altitude, and Refresh tab on their default values, but let’s discuss these items first. The Refresh tab allows you to automatically set the image overlay up to refresh to the latest view of the image. This is used when the image that you’re placing updates frequently, but in our case the image is static so we don’t have a need to refresh our image. The refresh functionality is useful when dealing with data such as weather radar images that are continuously updating. Refreshes can occur based on a time interval or based on a view that has changed. The altitude tab can be used to display the image a set distance above the ground for situations where you want the image to “hover” above the terrain. Again, in this case we do not need our image to hover, but it can be useful in some instances. Finally, the View tab can be used to set the current camera properties for the 3D viewer.
6. Now that we’ve defined the position of our image your GE viewer should appear as follows:
7. There are a number of things that we can do to enhance this view. First, we’ll set a transparency value on our image so that we can “see through” the image to the underlying terrain and vector data. With Abajo Peak selected in the Places panel, use the transparency slider to apply transparency to the image.
Your image should now have a transparency set. You may need to experiment with the slider until you determine the best setting. Notice that as you move the slider, the underlying terrain becomes visible.
8. Now, let’s turn on the Terrain layer in the Layers panel to drape the image over the underlying terrain.
Notice how the image now conforms to the underlying terrain.
9. Finally, let’s tilt the display and experiment with the orientation to get a better view of Abajo Peak. Use the navigation tools provided by GE to get a better look at the image and underlying terrain.
Author Information
Mr. Pimpler is the owner of Geospatial Training Services, LLC, a provider of virtual and instructor led GIS training opportunities. For more information regarding training opportunities provided by GeoSpatial Training Services, please visit our website at http://www.geospatialtraining.com. Our “Google Maps For Your Apps ” and “Integrating ArcGIS Data with Google Earth ” courses provide detailed information about Google Maps and Google Earth. Each course provides detailed audio and hard-copy lecture materials, visual demonstrations, and exercises designed to supplement the materials presented in our lectures. In addition, you can now purchase these courses as a bundle. Click the links provided above for more information.
Top iPhone related GIS and Geo Tech news stories from 2009 - At the end of the year its always interesting for us to look at some of the stats and results to identify trends and more important, to see what our readers think is hot! In the "news" category it seems that iPhone related geo tech items were extremely popular.
Geo Social Location Checkin to Twitter from iPhone - With the cool SXSW event taking place Austin, TX, everyone who's anyone in social and social location seems to have rolled out updates this week, making your choice for how to check-in to your social media bookmarks even tougher to decide on!
10 Awesome GIS and Mapping apps for the iPhone - I recall last year at the ESRI UC when an iPhone was on stage showing a prototype app (think ArcPad on iPhone). It was then that I realized the iPhone platform is going to be BIG in mapping and there's a ton of opportunity for developers.
Nokia Booklet 3G, unboxing video and image gallery... Those of you in the USA who pop in to BestBuy occasionally, you may have seen a stand showing off the Nokia Booklet 3G. A sleek, 3G enabled, SIM slot (AT&T) sporting netbook.
Interesting Tweeple - 10 Geo Technology & Geo-Social Women of Twitter - given the growing love for geospatial and location-aware technologies, I’ve decided to hype 10 women that I feel make a significant contribution to the Geo-Twittersphere. If you’d like to add 10 knowledgeable and useful Twitter contacts to your Geo following list I highly suggest the following: (in no particular order)
10 Geo Social Location-Aware Apps Making Waves... With Twitter's opening of their location API to developers there's going to be a ton of third party apps that will enable Twitter users to share location-aware information via their Twitter accounts.
Signs that indicate you may be a GeoGeek (aka. GeoNerd) and some suggested Geo blogs - Chances are good that if you are a Geo Geek then you already know it and likely refer to yourself as one. However, there’s many of you out there that may be on the fence and wondering… “am I a Geo Geek?" Read on for a comprehensive list of signs you might be a GeoGeek followed up by some suggested Geoblog reading.
Real-time GPS Mapping and GIS Solution Aids Efficient Disaster Management - Saturday, February 7, 2009 will forever be known as Black Saturday in the State of Victoria, Australia. In the midst of a 10-year drought, a record breaking heat wave descended upon the state, with temperatures exceeding 45 degrees C (110-120 deg F), breaking all-time record highs in some cities - Victoria Police Use Trimble Juno SC Handhelds to Speed Assessment of Damage Caused by Bush Fires.
2010 ESRI Federal User Conference February 17-19, 2010, Washington D.C. Walter E. Washington Convention Center - The FedUC is the largest geospatial conference for federal agencies. Connect with other leaders, decision makers, and GIS professionals.
The International LiDAR Mapping Forum 2010 - Tenth Anniversary Event! ILMF 2010 will be held from March 3 - 5, 2010 at the Hyatt Regency in Denver at Colorado Convention Center.
The NAVTEQ 2010 Global LBS Challenge Awards Ceremony will be held during Ignite at O'Reilly Where 2.0. Be among the first to hear as NAVTEQ announces the winners for the North America region. Participants will be competing for a global prize pool of $10 million and growing by showcasing pre-commercial location-enabled apps using NAVTEQ map data & products. March 30, 2010, during Ignite Where, 7:30pm - 9:00pm, at the Marriott San Jose, CA
WHERE2.0 2010 - Now in its sixth year, the Where 2.0 Conference is where the grassroots and leading edge developers building location-aware technology intersect with the businesses and entrepreneurs seeking out location apps, platforms, and hardware to gain a competitive edge. For 15% use Discount Code: whr10lbs
See more 
