GEOG 372: Introduction to Remote Sensing

Fall 2007

November 2nd

 

Laboratory 10

Multi-temporal Change Detection

 

No late labs can be accepted. Please type the answers just below the questions and hand the printouts at the beginning of the next lab: November 14th (0102) and Nov 15th (0101). Also do not forget to mention your MAJOR on your labs

 

This laboratory exercise will focus on change detection via visual interpretation methods. The first half will focus on change seen over a time period of several years and the second half will focus on seasonal and phenological changes seen over the course of one year. For this exercise we will be using images located in U:\\g372\372-fall07\lab10data in the sub folders 'landsat' and 'modis'.

 

Open ENVI 4.2.

 

Landsat Inter-annual Change Detection:

 

Open all the files located in the landsat folder. When all 6 bands are loaded, look at the file names in the Available Bands list. Notice there are three bands for June 18, 2002 and three bands for May 16, 1987. Also notice all bands are from the same Landsat path and row, meaning they cover the same area. We will use these 2 images to visually assess change in the area over a 15-year time period.

 

Load into a display a 5,4,3 RGB composite of the 2002 image.

Load the same color composite for the 1987 image into a second display.

Link the displays.

 

1. What landcover feature shows up as green? Why?

2. What landcover feature shows up as pinkish-red? Why?

3. What landcover feature shows up as black? Why?

4. What landcover feature shows up purplish? Why?

5. What image feature shows up as white in only 1 image? Why?

 

Look at each of the below points. For each point, list and describe what the feature is for 1987 and 2002 and give a reason for what may have happened to cause the change.

 

6. 4123, 3290

7. 2357, 3197

8. 5787, 5326

9. 5647, 4373

10. 4789, 2756

 

Look at both images in the Scroll viewer.

 

11. What difference do you see between the two for the Eastern Shore? What would cause that difference?

 

Take a screen shot of your displays.

 

Close all image display windows.

 

MODIS Intra-Annual Change Detection:

 

For this portion of the laboratory, we will be examining and comparing 2 MODIS NDVI 16-day composite images, one collected from December 18-31, 2004 and the other collected from May 9-24, 2005. The images were composited to accumulate the best, clearest pixels in the 16-day period and then had the NDVI equation applied to show varying levels of greenness.

 

Open the two files located in the modis folder. Click on WGS 84 for the datum. You will need to click OK twice, once for each image if you selected them both to load together. When the 2 bands are loaded, look at the file names in the Available Bands list. Notice there is 1 band for 2004 and 1 band for 2005. The numbers following the years represent the middle Julian Day for each composite period.

 

Load each MODIS band into a separate display in gray scale. Link the displays and drag the corners of your 2 scroll images to make them larger.

 

12. Look at the southeast US. Which image is brighter in this area? Why?

13. Look at the northern US and Canada. Which image is darker in this area? Why would this area be almost black?

14. Look at the southwest US excluding the Pacific coast/California area. Why are both images darker tones of gray in this area?

15. How would an archive of composite 16-day NDVI images from the 1970's to present help a researcher study climate change (i.e. global warming) and climate variability (i.e. El Nino/La Nina, drought, or surplus precipitation)? Write a paragraph or so.

 

 

Log off your computer and turn off the monitor when you are finished.

 

Typed answers are due November 14th (0102) and Nov 15th (0101), 2007