Differences between revisions 14 and 16 (spanning 2 versions)

INIT_LITHOS.TXT

Description

This text file sets limits, definitions, and logicals for SPC.

Here is a sample 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.

Operational settings for INIT_LITHOS.TXT. There are other options, but they are not needed or supported for the OSIRIS-REx mission

USR= '0'
USRMX=12
BODY='RQ36'
IDCODE=2101955
#BFRAME='RQ36_FIXED'
BFRAME='IAU_BENNU'
PCK='DATA/naif0011.tls'
PCK='DATA/bennu_v10.tpc'
UNIT='METER'
ASIG= 0.05
SSIG= 0.15
CHI0= 1.0
BLIM= 0.5
MXSLP=0.6
BLOOM=0.2
SEED= 1.3827453
#REFLECT= 'VESTA'
NEWLIM=.TRUE.       find new limbs in LITHOSP
SOFTEN=1
MAPONLY=.FALSE.
#GEOPIC='pict1.txt'
RENAME=.FALSE.
REGFLG=.FALSE.
REG='J0'
KB=1
RPLUSE=.TRUE.
RECVR=.FALSE.
#RECVR=.TRUE.
ALPAD=.TRUE.
NEWLIM=.TRUE.
DISTORT= 'M###########' 'OWEN'  6
0.00000D+00        0.00000D+00    0.0000000-06    0.00000D+00    0.00000D+00    0.000000D-05   0.0000000D-07
DISTORT= 'P###########' 'OWEN'  6
0.00000D+00        0.00000D+00    0.000000D-06    0.00000D+00    0.00000D+00    0.000000D-07   0.0000000D-06
#SHAPERF= 'SHAPEFILES/SHAPE00.TXT'
#SIGMARF= .05
LMKWTS= 1, 1, 1, 0      WB, WO, WL, WR
PICWTS= 1, 1, 0, 1, 0      WB, WL, WC, WS, WT
#POLE:
#LMKWTS= 1, 0, 0, 0      WB, WO, WL, WR
LPCORLM= 0.2
ALCORLM= 0.3
GDCORLM= 0.3
HTCORLM= 0.2
CORRFLG= 3         0:LAP, 1:ALB, 2:GRD, 3:L+A
RESLM= 4           PIXEL<RESLM*SCALE [SCALE>PIXEL/RESLM]
PICLM=2
NUMLM=200
SIZLM= 1.5        ^ LOWERS PIXEL/SCALE
END

The following table shows additional parameters that may be used in INIT_LITHOS.TXT:

USRMX	When running any batch script program (make_scriptP, make_scriptAP), this value defines the number of processors that will be used
BODY	The is the name of the object
IDCODE	The is the number that NAIF uses to denote which object is being used. Bennu's official asteroid designator is 2101955
BFRAME	Contains the variable used to define the body fixed coordinate frame. This is defined by NAIF and used in the kernels
PCK	These define the planetary constants for a variety of objects. naif0011.tls is for the whole solar system. bennu_v10.tpc is the current version for Bennu. Many programs will read these line to do SPICE function calls.
UNIT	Sets the units that the tables report out units. Options are KILOMETER and METER
ASIG	The weighting that is placed upon the albedo solution. Default is 0.05
SSIG	The weighting that is placed upon the asteroid's topographic solution.
CHI0	Default is 1.0.
BLIM	Default is 0.5.
MXSLP	Default is 0.6.
BLOOM	Default is 0.02.
SEED	The seed value used for the random function call.
REFLECT	What photometric model to use. If not defined, SPC uses McEwin .

BLEMISHES='FC2#########'	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.
PRNLM=100	Prune limit used by residuals to alert you if the number of pictures containing a landmark exceeds the limit. Landmarks exceeding the limit are listed in the output file PRUNE.TXT.

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.
WC - Camera. The uncertainty value for SIGMA_PTG in SUMFILES will constrain how far away the camera pointing solution can be from the value stored in NOMINALS
WS - SCOBJ. The uncertainty value for SIGMA-VSO in SUMFILES will constrain how far away the spacecraft object (SCOBJ) solution can be from the value stored in NOMINALS
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)

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