This text file sets limits, definitions, and logicals for SPC.
Here are two samples to show the keywords used in INIT_LITHOS.TXT.
The definitions on the right explain the keywords and are not present in the actual INIT_LITHOS.TXT file.
The following table shows additional parameters that may be used in INIT_LITHOS.TXT:
Reference to a template contained in BLEMISHES/ for masking bad pixels which are common to all FC2 images (example taken from DAWN). The template name is 12 characters, with the characters common to all affected images in the correct positions and '#' everywhere else. There may be multiple BLEMISH entries, each referring to BLEMISH template files.
Weighting values for landmark and picture calculations.
Within INIT_LITHOS.TXT, we have weighting that goes into the solution. The actual weight that is included is the sqrt of the value provided. Thus, if you want to double the weight, you would use 4.
LMKWTS -- Landmark Weights
These weights are used to influence the position of the central vector -- the middle of the landmark.
- WB - Body. Use the position from the pixel/line location based on the images.
- WO - Overlap. Condition the solution with the overlapping maplets
- WL - Limbs. Use images that contain the current landmark on its limb to condition the solution
- WR - Reference. If there is a reference object (SHAPEREF='SHAPEFILES/SHAPE00.TXT'), it will ensure the solution does not deviation too far from that baseline shape. This may be used at the start, but it is unlikely to be needed as the model gets more mature.
PICWTS -- Picture Weights
These weights are what is used when solving for the spacecraft position and camera pointing.
- WB - Body. Body is where it uses the position of all the landmarks and minimizes the spacecraft pointing/position.
- WL - Limbs. This uses landmarks that have detected that this image is on the limb to constrain it's position.
WT - Trajectory. When dynamics is being used (the preceding two and trailing two images are stored in the NOMINALS file), this will constrain how far the spacecraft object can deviate from the nearby images.
(Compiled by KD)