Lab 6

Image Restoration: Geometric Rectification       

Geog 418/518, Fundamentals of Remote Sensing

 

Name 1                                                       Name 2                                            

 

1.  Has the TM image been georeferenced (i.e., have geographic coordinates been assigned to the pixels)?  How can you tell?

 

 

 

 

2.      The SPOT panchromatic image has been georeferenced.  What system (projection) has it been georeferenced to?  

 

 

 

 

3.  What is the approximate size of one pixel (in meters) on the SPOT image?

 

 

 

 

4.  What does the Affine geometric model do?

 

 

 

 

5.  Are there circumstances where a large RMS error for a given pixel might be legitimate?  If so, give an example of such a circumstance.

 

 

 

 

 

 

6.  After your have adjusted your GCPs to the point where you are comfortable with the results, record the RMS error for your first 6 GCPs in the 1st order column in the table below.

 

 

GCP

Order of Polynomial Transformation

1st, RMS Error

2nd, RMS Error

3rd RMS Error

1

 

 

 

2

 

 

 

3

 

 

 

4

 

 

 

5

 

 

 

6

 

 

 

 

 

7.      Write down the equation for your 1st order polynomial transformation (look under the Transformation tab on the Model Properties window to get the constants).

 

 

 

 

 

8.      Now change the polynomial order to 2nd order and click Apply.  Write down the changes in your RMS Error in column two of Table 1 above (question 6).  Do the same for a third order polynomial.  In general, how does the RMS Error changes going from 1st to 2nd to 3rd order? Speculate on why the change occurs in this manner.

 

 

 

 

 

 

 

  1. Compare tmAtlanta_1st_near to the original tmAtlanta image.  Describe how the image has been changed.  Why has the image shifted in this particular manner?

 

 

 

 

 

 

 

 

 

 

 

 

  1. Compare tmAtlanta_1st_near, tmAtlanta_2nd_near, and tmAtlanta_3rd_near.  Which image or images seem to provide the best spatial portrayal of locations relative to the SPOT image? (Bring up the Spot image in a viewer, then link the images and zoom in on some road curves to get a good comparison)  How does this compare to what the RMS Errors from questions 6 and 8 suggested to you?

 

 

 

 

 

 

 

 

 

 

 

 

  1. Compare tmAtlanta_1st_near, tmAtlanta_1st_bilinear, and tmAtlanta_1st_cubic.  Can you detect any differences visually?  Try zooming in on some edges and straight lines.