Overlaps

(Main Menu Option O. Attach map to maps or limbs)

Description

This Main Menu option searches for overlaps and limbs for the specified maplet.

Suboptions

When you choose Option O. Attach map to maps or limbs from the Main Menu, you will see this set of prompts and Suboptions:

Main Menu: Q 0123O IUCRSG NVAMBX DEPL FZH? O
 >O
 Input 6-character landmark name.
r

 Reset all? (y/n)
n

 1. Automatic
 2. Manual
 3. Limbs
 4. Detach from limb or landmark
 0. Quit

Input 6-character landmark name. - Enter the landmark in one of these ways:

• by name - for example, 'EE0001'
• by typing 'r' or 'RECENT'
  • Both "r" and "RECENT" substitute for the last loaded landmark.

Reset all? (y/n) - Respond to this prompt to either:

• reset all overlaps - 'y'
• leave them as is - 'n'
  • Typically, use 'y' in case drifting causes maplets to no longer overlap one another.

1. Automatic - Automatically searches for maplets that physically overlap with the loaded landmark. "Physically overlap" means maplets whose center, GSD, and Q size indicate that they should overlap. Diagnostics will indicate if the albedo and heights are a match between the current maplet and another maplet, and will determine the position of each maplet on the loaded maplet (and vice versa). After these searches are performed, you will return to the Main Menu.

2. Manual - This option allows you to enter overlaps manually. The author has never used this option and will not attempt it until circumstances require it; it sounds tedious.

3. Limbs - Searches for pictures that have this landmark at their limb, thus constraining the distance from the center of the figure to the center of the maplet. After you choose this option, respond to these prompts:

• clear the existing limbs? (y/n) - say yes??

• Input expansion, res/scale limit, d_hgt limit

  • These inputs are similar to those used when building topography (Find heights). The values entered for 3. Limb search a wider area than those used when building topography.

4. Detach from limb or landmark - Enter the name if you want to remove an overlapping landmark/limb picture from the current landmark.

Typical Example

The following sample shows how to find overlaps and limbs. At the Main Menu,

1. load the landmark of interest
2. enter the following inputs

o
RECENT
y
1
o
RECENT
n
3
y
1, 3, 5

The first 4 lines find landmark overlaps. The remainder of the lines are typical for finding limbs.

Successful overlap

This sample shows a successful overlap output for each landmark that has a physical overlap:

EE0045
  0.0292  0.0321  0.9441  0.9996
  0.0069  0.0058  0.9442  0.9996
  0.0011  0.0011  0.9444  0.9996
  0.0002  0.0003  0.9445  0.9996
    0.0374    0.0393   -0.0031

EE0001
 -0.0107 -0.0742  0.7028  0.9995
 -0.0058 -0.0063  0.7082  0.9995
 -0.0024 -0.0004  0.7082  0.9995
 -0.0004  0.0002  0.7080  0.9995
   -0.0193   -0.0807    0.0060

The outputs for each landmark originate from the subroutine ATTACH.f, which determines the relative central vectors of two overlapping maplets as follows:

1. The overlapping maplet (LMK1) is projected into the coordinate system of the maplet-of-interest (LMK0).
2. A correlation is found by shifting LMK1.
3. The LMK0 central vector is updated.

This process is repeated for a total of four iterations. Here are the elements of the output:

• Lines 1-4 are outputs for each iteration:
  • Col 1 - pixel shift
  • Col 2 - line shift
  • Col 3 - correlation

    • Correlation depends on the INIT_LITHOS.TXT CORRFLAG parameter:

      • 0 - Laplacian; 1 - albedo; 2 - gradient; 3 - Laplacian/albedo
  • Col 4 - height correlation.]
• Line 5:
  • Col 1 - Total pixel shift;
  • Col 2 - Total line shift;
  • Col 3 - Average delta height.

Unsuccessful overlap

The overlap could also fail. In that case, it will throw a "below albedo correlation limit" or "below height correlation limit" in place of the rows of numbers.

Here are three samples of unsuccessful overlaps:

EE0126
  4.0764 -4.0374  0.2320  0.9825
  4.0366 -3.9734  0.2779  0.9730
  0.0072  0.0071  0.2842  0.9720
  0.0032  0.0021  0.2850  0.9720
  8.1234 -8.0016 -0.5042

EE0026
 No fit. Below height correlation limit
 HCOR =    7.1556346300126000E-002

EE0153
 No fit. Below albedo correlation limit
 ACOR =   0.29595196946445101

EE0043
 No fit. Below albedo correlation limit
 ACOR =   0.26043611639795511

EE0139
 No fit. Out of test area.

EE0025
 -2.2376 -2.8146  0.6090  0.9580
 -0.0506 -0.0554  0.6210  0.9581
 -0.0065  0.0016  0.6219  0.9580
 -0.0007  0.0003  0.6217  0.9580
 -2.2954 -2.8681 -3.0862

CategoryLithosOptions