Lab 7

Radiometric, Spatial and Spectral Enhancements        

Geog 418/518, Fundamentals of Remote Sensing

 

Name 1                                                       Name 2                                            

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1.      Using the Layer/Info tool, look at the general information and histograms for each band.  Fill in the table below, collecting spectral data for several water points and several forest points.  =

 

Band

Minimum value

Median value

Maximum value

Water pixel values

Forest pixel values

Unimodal or

Bimodal?

1

 

 

 

 

 

 

2

 

 

 

 

 

 

3

 

 

 

 

 

 

4

 

 

 

 

 

 

5

 

 

 

 

 

 

6

 

 

 

 

 

 

7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.      What two categories of features are driving the bimodal distributions in certain bands?  You can use the cursor inquiry tool if you need to determine which features correspond to which pixel values in a given band.

 

 

 

 

 

 

 

 

 

 

3.      Why is the band 6 distribution unimodal, while the surrounding bands (5 an 7) are bimodal?

 

 

 

 

 

 

 

4.      Why is there so little contrast on the image?  Explain in terms of the raw pixel values (see your table above) and the values these pixels receive on the screen.

 

 

 

 

 

 

 

 

 

5.      How does the breakpoint curve in the Breakpoint Editor window change?  Does it become steeper or shallower?

 

 

 

 

 

 

6.      Describe how the output histogram (the yellow one on your window) changes when you go from a standard deviation of 2.0 to 1.0.  Specifically, does the 1.0 std dev output histogram have more of fewer values in 240 to 260 range?  Why is this?

 

 

 

 

 

 

 

 

 

 

7.      Based on your table above, and assuming that the range is a it wider than the pixels you found, what range of values in band 4 would you want to stretch in order to highlight variations in the water?

 

 

 

 

 

8.      What color is everything outside the lake?  Why is this?

 

 

 

 

 

 

9.      Where are the darkest pixels in the lake area and why do they occur in these locations?

 

 

 

 

 

 

 

 

 

10.  Where are the medium and lighter gray pixels located in the lake.  Why do they occur in these relative locations?

 

 

 

 

 

 

 

 

 

11.  Now what shade is the lake and why is this the case?

 

 

 

 

 

 

 

12.  Examine the forest near the shoreline.  What is the range of tones you see now in this region?

 

 

 

 

 

 

13.  Which of the four approaches, if any, do the best job of picking up trails?  Zoom in on the area around Spenser Butte to check this out.

 

 

 

 

 

 

 

 

 

14.  Visit the NE corner of the images.  Which image does the best job  of mapping the housing and roads in that area?

 

 

 

 

 

 

 

 

 

 

15.  Given your answer to 14, what might be an application of edge enhancement detections for mapping purposes?

 

 

 

 

 

 

 

 

 

 

 

16.  How would you describe the differences between the 3x3, the 5x5 an the 7x7 edge enhancement figures in terms of texture, the size of objects you can discern on the images, and the range of grays you see on the image?