Digital Earth Weblog

If you are looking for aerial photography or satellite imagery, and just want to view it on screen rather than buy it, then www.earthetc.com would be worth a visit. [Disclosure: My company used to sell the software that runs that site.]

If you want to see a truly amazing image have a look at the satellite mosaic of the world. It is 2 terabytes in size, and you can view it in your browser across the Internet. All you need to do is install a small browser plug-in. It works by only downloading the data you need to display your current on screen view. You do not need to download the whole image, that’s the point of the technology.

Here’s how you do it:

1. Visit www.earthetc.com.
2. In the "Location/Type" column of the Imagery table, click on "World".
3. Click on "World TM742" to view the image.

Note: If you haven’t installed the ECW viewer plug-in before you will be prompted to do so.

Now you can pan and zoom as you please. I highly recommend zooming in over the Sahara desert and looking at the sand dunes. Some of the dunes are 1.5km from peak to peak! The geology around Wilpena Pound in South Australia is also worth a look.

If you are wondering why the image has some rather strange colours in it, that is because it has been created using bands 7, 4 and 2 of from the Landsat sensor. So what you are seeing is a visible representation of infrared light reflected from the surface of the Earth. Normally you cannot see infrared light, but this technique is used to highlight interesting geological structures on the Earth’s surface.

There are also natural colour images available at www.earthetc.com. Feel free to explore.