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How To Build A Landmark

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Eric E Palmer edited this page Oct 23, 2026 · 1 revision

How To Build A Landmark

Objectives

  • First we will generate a maplet with the following parameters:
  • center at -10, 350 (lat,wlon)
  • scale = .001 km/px
  • size: Q=49, width=99 x 99 px
  • name = ‘START5’

LITHOS: Create New Landmark

  • ** lithos**
  • c - create new landmark name
  • START5 - landmark name
  • l - define landmark control point by specifying a latitude and longitude on the body
  • -10 350 - lat, lon
  • .001,49 - enter scale (km/px), qsz

LITHOS: Input the new landmark

Once the landmark is created, you need to "load" it into active memory. You use the lithos command "i" from its main menu.

  • i - input landmark
  • START5 - landmark name (as previously named)
  • y - check for images?
  • 0.5 - fractional width. (This is almost always used)
  • n - reject invisibles

In a second terminal, review the LMRK_DISPLAY1.pgm image. You can use ImageMagick's "Display" command, Graphics Converter, or if using a Mac, pgm files can be displayed in the Finder or Preview.

  cd <working dir>
  ls -lt | head
  display LMRK_DISPLAY1.pgm

You can also use the SPC_Tools: landmarks

LITHOS: Eliminate Pictures from Landmark

  • e - eliminate pictures from landmark

  • n - auto-eliminate new images only (a for auto-eleiminate)

  • 0,50,.6,.6,0,4 - Input INVLIM,SLIM,CLIM,ILIM,RSMN,RSMX

    • 0 is typical. If you have objects that are obscuring the maplet, then this becomes important
    • 50 is the emission angle that we keep
    • .6 means the image must fill at least 60% of the frame
    • .6 means the illuminated service must fill at least 60% of the frame
    • 0 is minimum resolution -- almost always is 0
    • 4 is the maximum resolution ratio (how many times bigger are the image pixels than the GSD. 3 or 4 is typical. 6+ is seldom effective)

  • INVLIM = 1000 * MAX INVISIBLE FRACTION (0-1000)

  • SLIM = MAX EMISSION ANGLE (0-90)

  • CLIM = MIN FRACTION OF VISIBLE (0-1)

  • ILIM = MIN FRACTION IN SHADOW (0-1)

  • RSMN = MIN IMGSCALE/MAPSCALE (0-inf)

  • RSMX = MAX IMGSCALE/MAPSCALE (0-inf) =>set according to printout and LMRK_DISPLAY

  • Most permissible: 1000,90,0,0,0,inf => does not throw any image away

  • Least permissible: 0,0,1,1,inf,0 => throws all away

  • display LMRK_DISPLAY1.pgm

LITHOS: Get Heights from Shape and Find Normal, V

  • m - get heights from shape model
  • n - find normal
  • 2 - normal from heights
  • m - get heights from shape model
  • u - update landmark file (save)
  • 1 - save map

In 2nd terminal:

  cd Bennu
  ls -lt | head
  display LMRK_Display1.pgm
  more LMRKLIST.TXT
  more LMKFILES/START5.LMK
  more MAPFILES/START5.MAP
  showmap 
      START5

Then display the START5.pgm (xv, imageMagick, convert, GraphicConverter)

LITHOS: Align Landmarks in Pictures

Option 1. Use this when the template you see in LMRK_DISPLAY1.pgm is poor Option 2 (typical). Use this as much as you can
1 - align landmarks 1 - align landmarks
3 - align with picture 0 - align with template
23 - picture #2 in LMRK_DISPLAY 3 - enter spacing
1 - enter spacing n - new spacing?
y - new spacing? Yes b/c it only aligned a few images 0 - continue
2 - enter spacing y - update landmark pixel locations?
y - new spacing? Yes b/c it only aligned a few images 1 - align landmarks
3 - enter spacing 0 - align with template
y - new spacing? Yes b/c 3 caused a couple images to shift>10px 1 - enter spacing
2 - enter spacing n - new spacing?
n - new spacing? No, lets just use the correlated images first 0 - continue
0 - continue y - update landmark pixel locations?
y - update landmark pixel locations?
1 - align landmarks
3 - align with picture
1 - picture #2 from last iteration became picture #1
1 - enter spacing
n - new spacing?
0 - continue
y - update landmark pixel locations?
display LMRK_Display1.pgm

LITHOS: Find Template

  • u - update landmark file (save)
  • 1 - Save map
  • 0 - find template
  • c - use correlated
  • .5 - enter correlation limit
  • 0 - find template
  • 0 - continue
  • 44 - number of iterations display LMRK_Display.pgm

LITHOS: Align Landmarks and Find Template

  • 1 - align landmarks

  • 0 - auto align

  • 1 - enter spacing

  • y - new spacing?

  • 2 - enter spacing

  • n - new spacing?

  • 0 - continue

  • y - update landmark pixel locations?

  • 1 - align landmarks

  • 0 - auto align

  • 1 - enter spacing

  • n - new spacing?

  • 0 - continue

  • y - update landmark pixel locations? display LMRK_Display1.pgm

  • 0 - find template

  • c - use correlated

  • .5 - enter correlation limit

  • 0 - find template

  • 0 - continue

  • 44 - number of iterations display LMRK_DISPLAY1.pgm

REPEAT ONCE

LITHOS: Solve for Heights

  • 2 - find heights
  • 8 - fill with shape
  • 2 - include existing heights
  • .01 - input fraction of points
  • 1 - auto include neighboring maps
  • 4 - include limb vectors
  • 1,2.5,3 - input expansion, res/scale limit, d_hgt limit
  • 6 - include differential stereo
  • y - use gradients?
  • y - autoheights?
  • 0 - begin iteration
  • .025 - input weight
  • 30 - enter number of iterations
  • 0 - end iterations display LMRK_DISPLAY1.pgm display slope.pgm

LITHOS: Final Alignment and Save

  • 1 - align landmarks
  • 0 - auto align
  • 1 - enter spacing
  • n - new spacing?
  • 0 - continue
  • y - update landmark pixel locations?

*# We are skipping V-4 fo

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