Week 2 Image of the Week - America's Farm

You will work with several different images of the same coverage area to answer questions about remote sensing and learn what different images display to the observer. This imagery will extend your knowledge of 'remote sensing' using digital imagery.

Be sure to read the Image of the Week assignment on the Week 2 assignments page.

• Examine the ARDC Farm images. There are five images (4 different types). There are two Landsat True Color and Color Infrared images (7/25/1997), a DOQ (3/18/1994), and two ADAR images (7/4/1999)
• The two sets of dates that are similar will allow you to make some comparisons and answer the questions about what each type of image displays to the remote sensor.
• Answer the questions below and you will be on your way to becoming an 'expert' in 'remote sensing'.

For the ARDC imagery click here. (opens new window).

For a the large version of the ARDC imagery click here. (opens new window). (600 KB)

Resources to help with your questions. These are also linked in the ARDC imagery page.

Some Questions Part 1 (Remote Sensing):

1. In many farming areas, roads help define field boundaries. Often, the roads show up as straight lines and form a grid with one-mile squares. Find a mile square area in the enclosed image. Record the 'mile square' location. (You may locate items by specifying a general location, i.e. lower center, upper right, etc., or by using a grid with x-y coordinates.) Would this be easy to do in Banner County, Nebraska (Long Pine Butte, NE quad)? Area 51 (Sometimes referred to as Groom Lake, NV)? (another photo)

2. A 'center pivot' is one of the methods used for irrigation. A center pivot is a long pipe on wheels with attached sprinkler heads and one end attached to a water well. It sweeps out a circle that is visible from above. Record the location of a center pivot. Why is one part of the circle lighter than the other part?

3. Which areas appear to be strictly farm ground or field plots? How can you recognize these areas? Find an area that is likely to be grazing land.

4. A body of water usually appears black in this type of image because of low reflectance from the surface. Would water ever reflect as 'white'? Find regions that might be bodies of water. Can you find 'black areas' that are probably NOT bodies of water? Why not? Here is an image of a region just east of the ARDC farm. It shows a body of water. How can we recognize this object as a body of water? How is it different from any other features?

5. Find some buildings.

6. Find a road that does not follow N-S or E-W direction lines.

7. Another image is a view of section 29 of the farm. We are looking from the east in a westerly direction. Can you find this section on the air view? Can you see roads in this image? Can you locate some trees? What is the white thing in the center? What time of year is it? Winter? Fall? Spring? One way to confirm the 'reality' of remote observations, is to establish 'ground truths'. If you examine the location in question from the 'ground' and test for accuracy, you can be relatively sure about your observations. One way to establish a ground truth is to build a 'qtvr' (QuickTime Virtual Reality) movie. Here is a qtvr near the test plot area of the Farm.

Some Questions Part 2 (Imagery):

1. What are the advantages from a remote sensing standpoint of Landsat 7 image?
2. What are the advantages from a remote sensing standpoint of DOQ image?
3. What are the advantages from a remote sensing standpoint of True Color ADAR image?
4. What are the advantages from a remote sensing standpoint of False Color ADAR image?
5. State an example of a remote sensing opportunity where one type of image would be better than another.

Please proceed to the 'Assignment' link.