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'''7. Include shadowing''' - Standard procedure in SPC is to mask out shadows, which eliminates pixels that are fully in shadow. This option will take the masking of shadows a step further by masking out pixels that contain a portion of shadow in them. Note: ???, the preceding lines are how this option was explained to the author, but that is not what is written in R. Gaskell's code.
 *
[From LITHOS.f] Occasionally, a template will contain no data because a portion is not illuminated in any image. This option determines the maximum height that such a point can have and still be in shadow according to existing topography and randomly uses such values as conditioning heights. This is still an experimental procedure. It produces craters, for example, with sloped ramps in permanently shadowed areas.
'''7. Include shadowing''' - [From LITHOS.f] Occasionally, a template will contain no data because a portion is not illuminated in any image. This option determines the maximum height that such a point can have and still be in shadow according to existing topography and randomly uses such values as conditioning heights. This is still an experimental procedure. It produces craters, for example, with sloped ramps in permanently shadowed areas.

This option will solve for the brightness and slope of each pixel. It will use a variety of different options, including stereo and photoclinometry.

Example Display:

Main Menu: Q 0123O IUCRSG NVAMBX DEPL FZH? 2
 >2                                                                               

 TOOLS
 0. Begin integration
 1. Auto include neighboring maps
 2. Include existing heights
 3. Include shape vectors
 4. Include limb vectors
 5. Include external map
 6. Include differential stereo
 7. Include shadowing
 8. Fill with shape
 9. Include control points
 Q. Exit

Example Broken Down:

0. Begin integration - Asks to input weight for the conditioning heights; we always use .025. Next it asks for the number of iterations; typically we use 30.

  • After the iterations are finished you will enter "0" to go back to the Main Menu, "1" to enter in more iterations, or "2" to change the weight.

1. Auto include neighboring maps - Includes data from surrounding maplets that have been added to the "overlap" list. If you are building a maplet for the first time there won't be any overlaps assigned, so this option won't be needed until later.

  • [From LITHOS.f] This provides conditioning heights from overlapping maplets. Points on the overlapping maplet are chosen randomly according to a fixed formula that provides more points (up to 5%) if the overlapping maplet is higher resolution than the target maplet, 2.5% if resolutions are the same and dropping to zero at low resolution overlap. The projection is done by the subroutine GET_MAP (see abstract).

2. Include existing heights - This option uses heights from the existing topography as conditioning heights, with the fraction input by the user (typically 1%). This option will therefore weight data from the current maplet as well, that way the changes will occur slowly and remain stable. To the author's knowledge, this option will ALWAYS be used.

3. Include shape vectors - Author has no experience with this option.

  • [From LITHOS.f] This option provides conditioning heights from the existing shape model, with a fraction set by the user and heights from the subroutine GET_HEIGHTS. Option 3 is almost never used.

4. Include limb vectors - Constrains the solution by using limb data. Will prompt you to enter "expansion, res/scale limit, d_hgt limit". Entries can be separated by "Enter", " ", or ",". Expansion is only there for backwards compatibility, res/scale limit is refers to the resolution of the pictures that it searches for limbs, and d_hgt limit refers to the number of pixels away it will search for limbs. The last entry (d_hgt limit) is similar to the "Enter spacing" from Align landmarks (i.e. enter a number between 1 and 5). Typically we always use the values 1, 2.5, 3 for these entries.

  • [From LIMB_HEIGHTS.f] There are three user input search parameters. ZEXP is an expansion parameter that is always set to 1 but is kept for backward compatibility with old scripts. ZRES restricts the image RESOLUTION (in km/px) relative to the maplet SCALE: RESOLUTION < ZRES*SCALE. ZHGT is the maximum allowed difference between predicted limb point height on a maplet and the measured height in units of maplet SCALE.

5. Include external map - Author has no experience with this option.

  • [From LITHOS.f] This option gets conditioning heights from an externally produced map, with a fraction set by the user and heights from the subroutine GET_MAP (see abstract). If the fraction is set to zero, the option fills missing data areas with slopes from the external map, in much the same way as option 8, but with less granularity. If used in this context, option 5 should always be used before option 8. Note that this option may be used twice, once to provide conditioning heights and once to fill in missing slopes. Option 5 is the natural interface between SPC and other sources of topographic data such as SPG or scanning lidar.

6. Include differential stereo - This option will calculate stereo points at random locations on the maplet. Testing has shown this option is a good way to keep maplets from tilting at the edges. After entering this option it will ask if you want to use gradients (say "y") and autoheights (say "y").

  • [From LITHOS.f] This option determines conditioning heights from differential stereo. Features in a maplet move on trajectories as their heights change, owing to the obliqueness of its appearance in an image. The subroutine STEREO (see abstract) uses differences in these trajectories from image to image to determine conditioning heights.

7. Include shadowing - [From LITHOS.f] Occasionally, a template will contain no data because a portion is not illuminated in any image. This option determines the maximum height that such a point can have and still be in shadow according to existing topography and randomly uses such values as conditioning heights. This is still an experimental procedure. It produces craters, for example, with sloped ramps in permanently shadowed areas.

8. Fill with shape - If there are any "holes" in the maplet due to missing imagery, this option will fill those holes with the shape model.

9. Include control points - Author has never used this option.

  • [From LITHOS.f] This option is some paleocode that uses landmark centers as conditioning heights. It is never used.

Q. Exit - Exit to the Main Menu.

Typical Example

Here is a typical example one would use for Find heights if starting at the Main Menu. Sometimes option 6 or 7 (or both) will be removed, but the others are typically present.

2 | Find heights option

8 | Fill w/ shape

2 | Include existing heights

.01 | weighting

1 | Include overlaps

4 | Include limbs

1, 2.5, 3 | inputs for limbs

7 | Include extended shadowing

6 | include stereo

y | use gradients

y | use auto heights

0 | Begin integration

.025 | weighting

30 | number of iterations

0 | End iterations


The following output begins with the 0 from "Begin integration"

0
 0
 gc seeds.pgm

 input weight
.025
 Enter number of iterations
30
    -0.33759     0.34356    -0.34050     0.41873

 gc slope.pgm

    -0.28767     0.27729    -0.25837     0.36825

 gc slope.pgm

...
    -0.22599     0.18857    -0.16774     0.26969

 gc slope.pgm

    -0.22600     0.18859    -0.16777     0.26958

 gc slope.pgm

 0. end iterations
 1. more iterations
 2. change weight
0                                       
 -8.18594598952327801E-006

 Current landmark = EE0001
SCALE =  0.000100 QSZ =   49
 Lat/Lon/Rad =     -6.800   264.090     0.266
 Region = EE

 gc LMRK_DISPLAY0.pgm
 gc LMRK_DISPLAY1.pgm


 check display
Main Menu: Q 0123O IUCRSG NVAMBX DEPL FZH? 

Find heights (last edited 2022-03-14 13:37:31 by JohnWeirich)