Skip Navigation

University of Nebraska–Lincoln

  • Virtual Nebraska Logo

Virtual Nebraska

Educational Modules

Teacher Page

Helpful Hints

  1. Allow students to search the database for cities that they might be interested in before doing the activity. Give the students a class period to accomplish this. The database can be found at Nebraska Cities Search
  2. Once an image has been selected copies can be made by choosing the "Print" option. If you do not have a color printer, printing would not be recommended as you would loose the color. CASDE will print copies for 25 cents per copy (8 1/2" by 11"). Any inquiries about copies can be e-mailed to webmaster@casde.unl.edu. Larger posters can be produced as well by going to Ordering Posters
  3. Laminate copies for multiple use.
  4. Have students use overhead markers so they can be easily erased on laminated copies.
  5. Question #3 Hint. The city should have some obvious features such as roads, etc. but it should also be noted that the color is usually a cyan/blue. Cement and asphalt often reflect a cyan/blue color in a color-infrared image. Soils often reflect more of a cyan/green color.
  6. #5 Hint. The red represents plants that are reflecting infra-red electromagnetic radiation. Healthy live plants will reflect high amounts of infra-red radiation.
  7. #6 Hint. Soil and Cement reflect the cyan/green/blue color. Cement and Soil will absorb infrared. The complimentary color of infrared/red is cyan/green so that color is visible or reflected.
  8. #7 Hint. Different stages of growth, the health of a plant, as well as different types of vegetation will cause different shades of red. Corn canopies (covers) the soil and has a high reflectance of infra-red so it appears bright red whereas soybeans or weeds allow the soil to be exposed resulting in darker shades of red or perhaps even a cyan/green color. The time of year also is a key in determining why the image the way it is. If the image was done early spring or perhaps late fall, little to no red color will be seen (No plant matter to reflect the infra-red). If the image was done middle to late summer, red will be a dominant color because of the maturity and fullness of plant growth.
  9. #8 Hint. In the sandhills, prairie grass is the predominate vegetation. Prairie grass does not cover the canopy so your image will appear mainly cyan/green. In areas where agriculture vegetation is the predominate plant the image will appear mainly red. Keep in mind the climate as well. In western Nebraska, rainfall is minimal so often you image will not show a lot of red because of the arid climate. The geography of the land will also dictate color. Very steep hilly areas have less vegetation growth so that area will have a cyan/green or brownish color, etc. Many conclusions can be reached about climate, geography, etc. by looking at infra-red images.
  10. #9 Hint. Some of the images are mosaiced together by up to 20 smaller images. If the conditions where not optimal, the images were taken at different days and sometimes the dates could be months apart. When you mosaic two images together that are months apart, vast differences in vegetation growth along with the amount of water flowing in a river, etc. can be seen. The image of Fremont is a great example. Concentrate along the river and you will see a major difference in an area where two images were taken at different times of the year. One of the images was taken in the spring (high water) and one was taken later that summer (low water). You can also see the differences in the vegetation and its reflectance of infra-red radiation. The spring mosaic image will not show up as red as compared to the image taken later in the summer. Another possibility is cloud cover. Two images can be taken in the same day but if there is a slight increase in cloud cover between the first image and the second image, it will cause noticeable differences in the colors that are produced by the mosaiced image.
  11. #10 Hint. Find a country mile outside of the city limit. All roads are sectioned off into miles, thus a country mile! Convert to meters if you wish.