CKSMRG User's Guide =========================================================================== Last revised on 2010 JUN 03 by B. V. Semenov. Abstract -------------------------------------------------------- CKSMRG is a command-line program that merges segments in Type 3 CK files. Summary -------------------------------------------------------- CKSMRG is a program that takes an existing type 3 CK file, finds in it all segments that match a specified structure/reference pair, merges the data from these segments, and writes merged segment(s) out to an output Type 3 CK file. While doing this, it re-computes interpolation intervals boundaries based on a specified tolerance, regenerates, if requested, angular rates and optionally applies a time offset to the input CK time tags. CKSMRG can also down sample input CK data to produce output CK file of a smaller size matching the attitude in the input CK at or better than specified angular threshold. Normally this program is used to merge segments in the CK files that were created from the same input data stream, for example daily CKs created from orientation telemetry. In some cases a few CKs must be concatenated together using DAFCAT and resulting concatenated file should then be used as CKSMRG input. NAIF strongly advises to NOT use this program to merge CKs containing data that came from two or more different input data streams, for example reconstructed and predicted CKs. Usage -------------------------------------------------------- To make a new type 3 CK file containing a merged segment(s) for a set of homogeneous type 3 segments from an existing CK file: > CKSMRG -K|-KERNELS -I|-INPUT -O|-OUTPUT -S|-SEGID -F|-FILEID -B|-BODY -R|-REFERENCE -A|-AV -T|-TOLERANCE [-C|-CORRECTION ] [-D|-DOWNSAMPLE ] To display help: > CKSMRG -H|-HELP To display usage: > CKSMRG [-U|-USAGE] To display version: > CKSMRG -V|-VERSION Command line parameters specified in [] are optional. Command line keys are case insensitive. Depending on the value specified with -A/-AV command line switch the program copies angular rates from the input file to the output file (KEEP), re-computes angular rates using a straight (MAKE) or averaged (MAKEAVRG) approach, or ignores them and produces an output CK segment without angular rate information (DROP). Optionally the program can apply an offset to the orientation data time tags from the input CK file. The value of the offset can be specified in two ways -- directly with the -C/-CORRECTION command line switch or via a correction table file, the name of which can be provided after -C/-CORRECTION command line switch. An example of the first case would be '-C -2.3 seconds', which tells the program to subtract 2.3 seconds from each time from the input file before writing it to the output file. In the second case, '-C corr_table.txt', the specified correction table file should be a plain text file containing one or more lines with three space-delimited items on each line. These items are starting UTC time (without embedded blanks), correction value, and correction units. For example, this correction file: 2002-02-01T00:00 2.0 seconds 2002-03-01T00:00 -4.5 seconds tells the program that all time tags before February 1, 2002 should not be corrected, 2 seconds must be added to all time tags falling in February, and 4.5 seconds must be subtracted from all time tags after March 1 00:00. Optionally the program can also down sample input CK data to produce a smaller output CK file still providing attitude that matches input attitude at or better than angular threshold specified with -D/-DOWNSAMPLE command line switch. Note that this capability should be exercised with caution because some data from the input CK does not get copied to the output CK file. This loss of data makes the output CK file not as usable for further alterations, for example such as changing interpolation interval information, as the input CK file. Using too tight angular threshold may also result in making output CK with too many points in a single segment making access to the data in the segment via CK reader routines inefficient. Usage Example -------------------------------------------------------- For example, imagine that there is a CK file containing a few type 3 CK segments with orientation data for a structure with NAIF ID -53000 with respect to the MARSIAU reference frame (the case for Mars 01 Odyssey CK files). The angular rates stored in the segments of this file were originally computed from the orientation data. This program can be run in the following fashion to generate an output type 3 file, in which the data from the input segments will be merged into a single segment: > CKSMRG -K m01.lsk m01.sclk m01.fk \ -I m01_input_ck.bc \ -O m01_output_ck.bc \ -S 'Merged M01 s/c Segment Desc.' \ -F 'New M01 s/c File Desc.' \ -B -53000 \ -R MARSIAU \ -A MAKEAVRG \ -T 1 minutes