This lithos option will search for overlaps and limbs for the specified maplet.

Example Display:

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

Example Broken Down:

Input 6-character landmark name. - After selecting the "O" option the user is asked to enter a landmark. The landmark can be entered by name (ex. EE0001) or by typing "r" or "RECENT". Both "r" and "RECENT" will substitute for the last loaded landmark.

Reset all? (y/n) - This option is to reset all overlaps ("y"), or leave them as is ("n"). Typically one will 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 overlapping" means maplets whose center, GSD, and Q size indicate they should overlap. Diagnostics will be reported indicating if the albedo and heights are a match between the current maplet and another maplet, and determines the position of each maplet on the loaded maplet (and vice versa). After these are performed the user is returned to the Main Menu.

2. Manual - This option will allow the user 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. Will ask if you wish to clear the existing limbs (y/n) and then asks the user to "Input expansion, res/scale limit, d_hgt limit". These last options are similar to those when asked when incorporating limbs when building topography (Find heights). The values entered while searching for limbs search a wider area than when including the limbs when building topography.

4. Detach from limb or landmark - To remove an overlapping landmark/limb picture from the current landmark, enter in its name here.

Typical Use

To find overlaps and limbs, the typical procedure is to enter the following into the Main Menu after you've loaded the landmark of interest.

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

The first 4 lines above find landmark overlaps, the output will look like the following for each landmark that has a physical overlap. The remainder of the lines are typical for finding limbs.

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 above is an example of a successful overlap. The outputs for each landmark originate from the subroutine ATTACH.f which determines the relative central vectors of two overlapping maplets as follows.

The overlapping maplet (LMK1) is projected into the coordinate system of the maplet-of-interest (LMK0), a correlation is then found by shifting LMK1, finally the LMK0 central vector is updated. This process is repeated for a total of four iterations.

• The first four lines are output for each iteration:
  • Col 1 - pixel shift
  • Col 2 - line shift

  • Col 3 - correlation (depending on the INIT_LITHOS.TXT CORRFLAG parameter: 1 - Laplacian; 2 - albedo; 3 - gradient; 4 - Laplacian/albedo.)

  • Col 4 - height correlation
• Fifth line: New landmark central vector.

The overlap could also fail and throw a "below albedo correlation limit" or "below height correlation limit" in place of the rows of numbers. Examples of unsuccessful overlaps are displayed below.

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