Downloading Aerial Photography and Orthoimagery
Click to enlarge.
This aerial photograph of Claremont School in Oakland, California shows cars, trees, basketball courts (including the shadow of the backboard), and even individual classroom windows. Follow the instructions below to download a free image of your school! The clarity of the photos varies by region, with the best quality images covering urban areas throughout the country.
For mapping purposes, orthophotos are better than air photos. What is an orthophoto? It's an air photo that has been corrected for distortions that are created by topography and the camera angle. In many cases, data has also been attached to the file so computer software recognizes the exact location of the image. A Digital Orthophoto Quad, or DOQ, is an orthophoto with boundaries that match the boundaries of a comparable topographic quadrangle. Most of what you see on the Internet that is identified as an air photo is actually an orthophoto.
To obtain a high resolution orthophoto (or aerial photo) of your school or home:
- Go to the USGS Earth Explorer website.
- You can view images online, but in order to download them (free) you must first log in. Registration is free. To register, click on "Register" at the top right of the screen.
- Once you are logged in, return to Earth Explorer's home page. Type the address of your home or school on the left side of the screen and click on "Show". An image will appear on the right side of the screen.
- Use the Search Criteria boxes to narrow your search.
- Click on "Data Sets" at the bottom of the left column, then click on the plus sign beside "Aerial Photography". You now have the option of selecting different kinds of air photos and orthophotos. Your best option is "High Resolution Orthoimagery", but this only covers urban areas and might not be available for all locations. If your area isn't covered, select "DOQ" instead. Click on "Results" at the bottom of the left column.
- A list of images that match your search criteria will appear in the left column. Select the image that you want, and click on the icon with the green down arrow. Follow instructions to download the image.
Alternative Source: The USGS has a new product called the US Topo. This is a computer-generated topographic map, with layers that can be turned on and off. One of those layers is an orthophoto. As of June 2011, US Topo maps are only available for about 50% of the U.S. All states will be available by the end of 2012. US Topo maps are updated every three years. Downloads of US Topos are FREE.
- Before beginning, make sure you have Adobe Reader on your computer.
- Go to the USGS Store website: http://store.usgs.gov
- Click on either "Map Locator" or "US Topo". Both links take you to the Map Locator. US Topo Maps are available for all red areas.
- To access the full functionality of a US Topo map, you need a FREE TerraGo toolbar. Go to the TerraGo box at the bottom of the Map Locator page and click on "Download Now". Follow the TerraGo registration and download instructions to download a FREE TerraGo toolbar.
- Return to the Map Locator page on the USGS Store.
- Use the zoom to navigate to the location of your school.
- On the right side of the screen, click on the circle beside "Mark Points". Your cursor will change to a cross.
- Click on the location that you would like to download. A red balloon will appear on the map.
- Click on the red balloon to get a list of available maps for that location. Any of the maps can be downloaded for free (or you can order paper copies). Click on "download" for the US Topo of that area (if it's available).
- Follow directions to download the file.
- The "US Topo Quickstart" link has detailed instructions for downloading files and working with the TerraGo toolbar.
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