# INIT_LITHOS.TXT

Category B |
Version 3.0 |

## Description

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

Here is a sample to show the keywords used in **INIT_LITHOS.TXT**.

Operational settings for INIT_LITHOS.TXT. There are other options, but they are not needed or supported for the OSIRIS-REx mission. # as the first character denotes a comment.

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 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

Explanation

USR |
Not used |

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 the object. 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 (a priori albedo sigma). Typical is 0.05. EDIT JRW 09 May 2017: This value determines how much to change albedo during 0-0-40. Setting it small (1e-10) means albedo won't change. |

SSIG |
The weighting that is placed upon the asteroid's topographic solution. (a priori slope sigma). Typical is 0.15 |

CHI0 |
Background limit. Typical is 1.0. |

BLIM |
Minimum overlap in LITHOS b option. Typical is 0.5. |

MXSLP |
Sets the limit for slope. Previous use at 0.6 ensures no vertical slopes. Suggest removing or 0 for Bennu and boulders. |

BLOOM |
Enables limb detection when blooming is present. Typical 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 . |

SOFTEN |
This decreases the weight of the change when a solution is found. Typical is 1.0. |

MAPONLY |
If .TRUE., we ignore mapless landmarks in GEOMETRY. Standard is FALSE |

REGFLG |
If .TRUE., it uses an alternate LANDMARK naming convention. |

REG |
If REGFLG=.TRUE., it uses these two characters as the lead character for LANDMARKS. |

KB |
Beginning number in sequence for LANDMARKS. Typical is 1 |

RPLUSE |
Use PICTLISTX or PICLTLISTR for netpictures. Typical is .TRUE. |

RECVR |
If .TRUE., prevents high res maplets from effecting low-resolution topography. Typical is .FALSE. |

ALPAD |
Perform extra albedo solution after each iteration. Typical .TRUE. |

NEWLIM |
Tells lithosP to run the detect new limb routing when running an iteration. |

DISTORT |
Distortion matrix. It has four parameters. The first is an image name template where # is a wildcard. If the image name fits the template, then it will apply this distortion matrix. The next parameter is the distortion type. The third parameter is how many terms the distortion matrix has. The fourth parameter is the distortion matrix. (Note: The zeroth distortion matrix element is a fractional focal length change for the particular filter.) |

SHAPEREF |
If you want to constrain the model using a starting shape model (GEOMETRY option 1), that model is defined here. Typical is "SHAP00.TXT. |

SIGMARF |
Simga is km for above constraint. Typical is 0.5. |

LMKWTS |
Weights for generation for the LANDMARK position (GEOMETRY option 1). Typical is 1, 1, 1, 0 (see details below) |

PICWTS |
Weights for generation for the S/C position and pointing (GEOMETRY option 2). Typical is 1, 1, 1, 1, 0 |

LPCORLM |
Correlation limit for laplacian cor. Typical is 0.2. |

ALCORLM |
Correlation limit for albedo cor. Typical is 0.3. |

GDCORLM |
Correlation limit for gradient cor. Typical is 0.3. |

HTCORLM |
Correlation limit for height cor. Typical is 0.2. |

CORRFLG |
Overlap correlation option. 0:LAP, 1:ALB, 2:GRD, 3:L+A. Typical is 3. |

RESLM |
PIXEL<RESLM*SCALE [SCALE>PIXEL/RESLM]. Limits image or maplet resolution in search. Typical is 4. |

PICLM |
Minimum number of images in a LANDMARK. If it doesn't this many, the LANDMARK is deleted. Typical is 6. |

NUMLM |
Number of images before RESLM kits in. If you have more that this number of images, don't add in resolutions ratios beyond RESLM. Typical is 200. |

SIZLM |
Minimum ratio of map to image sizes. MAPSIZE < SIZLM * PICSIZE. ^ LOWERS PIXEL/SCALE. Typical is 1.5. |

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 its 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)*