lithos
Aligns maplets to the current shape model and will provide slight changes to the shape (stored in MAPFILES).
Lithos is the key for SPC. It works on a single landmark, which defined the associated maplet. This landmark must be created (i.e. fully defined) and all the images that include it must be shifted so that everything is aligned. Once those are done, you can calculate the topography which includes identify other maps that overlap, creating a template, and then solving the whole system.
Lithos and LithosP are used by make_script(P) for batch processing. The mark_script program will create a script for each landmark that you will process, which is taken as input (e.g. lithos < LAND01.IIN > LAND01.OOT)
Build a template
- Option 0
Align images
- Option 1
Calculate topography
- Option 2
Housekeeping functions
- Option c - create a landmark
- Option i - "input" a landmark. Basically, start using the landmark.
- Option e - eliminate
- - Good values to use, "0 40 0.2 0.2 0 2"
- - Based on: Input INVLIM, SLIM, CLIM, ILIM, RSMN, RSMX
- INVLIM
- Fraction of the landmark that is obscured by other objects (that is in front)
- 1000 * max invisible fraction (0-1000).
- Suggested: 0
- 0 keeps everything
- SLIM
- Emission Angle: drop if greater than (0-90 degrees).
- Suggested: 40, eliminate images with big emissions angles.
- 90 keeps everything
- CLIM
- How much of the maplet is visible: Drop if less than (0-1.0).
- Suggested: 0.2, the image must only contain 20% of the maplet.
- 0 keeps everything
- ILIM
- How much of maplet is in shadows, drop if more than (0-1.0).
- Suggested: 0.2, the image cannot have more than 20% in shadow.
- 0 keeps everything
- RSMN
- Minimum ratio of the image to maplet, drop if less than (0 to inf).
- Suggested: 0, accept the highest resolution images you can.
- 0 keeps everything
- RSMX
- Maximum ratio of the image to maplet, drop if less than (0 to inf).
- Suggested: 2, reject images with less than twice the resolution of your maplet.
- 999999 keeps everything
Input - optional file
- aaa.INN - a script that sends batch commands
Input - stdin
- Basic steps
- Create a landmark, "C"
- Input a landmark (really that is selecting it for use), "I"
- Creating a template (the virtual idea of the topography and albedo based on the maplets), 0, 0, 40
- Aligning the maplets (0 for auto, 1 for manual, 2 for move all maplets, 3 to align to a specific maplet)
- Update and save, "U 1"
Output
- aaa.OOT
- landmark and map files
- LMRK_DISPLAY0.pgm
- LMRK_DISPLAY1.pgm -- stretched version
- slopeb.pgm - shows slope both in x and y
PowerPoint Notes
Description
- Creates landmark files, determines landmark topography (MAPFILE), and locates landmark center in images
Inputs
- INIT_LITHOS.TXT
- SUMFILESR
- SPC IMG
- NOMINALS
- SPICE
- MAPLETSL
Outputs
- SUMFILESL
- LMKFILESL
- MAPLETSL
- LMRKLIST.TXT
Process Overview
Maplet Definition
3D topography & relative albedo model of a portion of the surface
Control vector V from body center to origin of local coordinate system
- Local coordinate system axes ui(i=1, 3) with u3 normal to the local surface
- 2-D grid, typically 99x99 pixels with positions x=(x1, x2) relative to origin
- Local heights h(x1, x2) and relative albedos a(x1, x2) at each grid point
Camera coordinate system ci(i=1, 3) and S/C position W
- Maplet control point not tied to a specific surface feature
- Maplet pixel scale not tied to specific image resolution
Specifying a Maplet
- Maplets specified by selecting control point based on
- (1) pixel, line position of a given image
- (2) Lat/Lon
- (3) Relative to local coordinates (x1, x2) of existing nearby maplet
- Setting scale (km/pix), #pixels/row
(1) => (p, l) mapped onto surface, control vector V determined by bi-linear interpolation from heights of nearest 4 vectors of a-priori topography. Same with (2), (3)
- Construct local tangent plane and set u3 normal to local surface
Interpolate heights from a-priori topography to maplet pixels => h(x1,x2)
Picture Description
- Left: empty placeholder maplet wrt which we select maplet centers
- Right: Control point distribution on Enceladus based on Lat/Lon
Extracting Image Data
- Automatically find all images that contain area of given maplet, whole or in part, based on the a-priori geometry
- Automatically filter candidate images based on number of criteria such as;
- Resolution ratio between maplet/image scale (typically 1/3 - x3)
- Range of off-nadir view angles at maplet center (typically up to 60 )
- Brightness threshold of portion of image extract
- Any number of images (3 - few hundreds) used
- Maplet pixels projected in focal plane and image brightness resampled on maplet pixels via bilinear interpolation
Dark & invisible pixels are ignored & pixel brightness rescaled
Extracting Image Data With No A-Priori Topo Information
- Zero initial albedo
- Flat slopes from smooth sphere a-priori shape
- Predicted brightness is a near uniform value across template
Extracting Image Data With A-Priori Topo Information
- Resampled images at 175 m/pix projected on existing low-res topography at 500 m/pix
- Predicted brightness is derived from that low resolution topography
Menu Description
LANDMARK/MAPLET CONSTRUCTION
0. Find template
1. Align landmarks
2. Find heights
O. Attach map to maps or limbs
LANDMARK/MAPLET I/O AND CREATION
I. Input landmark
- Input 6 character name
U. Update landmark files
C. Create new landmark
- Input 6 character landmark name
R. Replicate or Rename landmark
- Input 6 character old landmark name
- Input 6 character new landmark name
- Delete old landmark? (y/n)
S. Change scale, qsz or orientation
G. Turn on rename
ADJUST INPUT DATA AND NOMINALS
N. Find normal
- Normal from radius vector
- Normal from heights
- Normal from shape
- Normal from stereo
V. Find V, Z or PTG
- V from Z and pointing
- Z from V and pointing
- PTG/SCOBJ from Z and V (selected image)
- PTG/SCOBJ from Z and V (current images)
A. Reset albedo or slopes
M. Get heights from shape model
B. Get heights from surrounding map
- List possibilities? (y/n)
if y
CP0002 0.0500 1.0000 CQ0004 0.0500 1.0000 CQ0008 0.0250 1.0000 CQ0009 0.0250 0.9822 CQ0017 0.0120 0.9153 DP0002 0.0500 0.8923 ...... ...... ......
- Input a 6-character name.
- 0 to cancel
- List possibilities? (y/n)
X. Turn on/off extract filter. Tol = 0.050
DELETE, ELIMINATE OR IGNORE FILES
D. Delete or Disconnect landmark
E. Eliminate pictures from landmark
c. Continue
a. Auto remove
n. Auto remove (new pictures)
m. Manual remove
p. Check peripheral visibility
o. Remove no-correlation pix
t. Auto change topo flag
For a, n, & t Input INVLIM, SLIM, CLIM, RSMN, RSMX
P. Picture status
- Tuck or untuck
- Toss
L. Turn off picture restriction
INFORMATION AND DISPLAY
F. Find maplets containing surface point
Z. Use zoom display
H. Hide screen output
Example of Finding a Tempalte
i
CQ0082 input landmark
n no new pictures (auto)
n no new pictures (manual
x turn on extract filter
.025 filter setting
0 (find template) CQ0082
CQ0082
Lat = 34.721
Lon = 30.609
Rad = 7.830
1 0.982 1.657 0.000 0.013
2 0.980 1.758 0.020 0.013
3 0.978 1.894 0.000 0.013
. . .
19 0.975 1.566 0.000 0.013
20 0.890 0.564 0.388 0.011 *
21 0.967 1.200 0.106 0.006
22 0.974 1.467 0.039 0.006
Example of Aligning Landmarks
Example of Finding Heights