This function requires a TeraScan MODIS license.
modisin [ parameter=value ... ] [ inputfile outputfile ] modisin [ parameter=value ... ] [ inputfile ... directory ]
Parameters are on_pass_disk, pass_number, pds_input, reed_solomon, channels, delta_500m, delta_250m, bowtie_filter, use_master, master_file, full_width, start_time, num_scans, start_sample, num_samples.
modisin creates TeraScan MODIS datasets from Terra and Aqua Direct Broadcast CADU files or Level-0 Production Data Sets (PDS) output by getccsds. Input telemetry data can be read from the pass disk or standard UNIX disk files. Output is either to a user-supplied directory or a user-supplied list of dataset names.
The user can specify one or more of the 36 MODIS channels to extract from the data. All 36 channels can be extracted by specifying 1^36 as the input.
The data can also be spatially subsampled. The overall spatial subset of data to be extracted can be specified in one of two ways:
1) the smallest rectangular area required to cover a region defined by a master dataset. 2) a rectangular area of specific size, beginning at a user-specified time and scan sample.
Answer yes if the input is from the pass disk, or no if the input is from a standard UNIX disk file.
Valid responses are [yes or no]. The default is yes.
This specifies the number of the pass to process when input is from the pass disk. Passes are
numbered starting with 1.
Valid responses are [1 to maximum number of passes that can be stored on your pass disk]. The default response is the number of the last acquired pass.
If input is from a file, the input file format is assumed to be PDS. If pds_input=no, the input data is assumed to be CADU.
When an input filename is provided on the command line, this parameter is OPTIONAL. If an input filename is not given on the command line, and on_pass_disk=no, the user is prompted for the pds_input parameter.
Valid responses are [yes or no]. The default is yes.
OPTIONAL. This specifies whether or not Reed-Solomon correction should be performed for CADU data (pds_input=no). Reed-Solomon is an encoding scheme used on Terra and Aqua CCSDS transmitted data that allows bit error identification and correction.
There is a significant tradeoff between processing speed and the potential extra data quality offered by Reed-Solomon bit error correction. Basically, reed_solomon=yes runs about 10 times slower than reed_solomon=no (it takes approximately 10 minutes to correct 10 minutes of data), and has diminishing benefit once the satellite is well above the horizon. When the data is ingested live (as part of live scrolling), reed_solomon=no.
Valid responses are [yes or no]. The default is no.
This is a list of the MODIS channels to extract from the data. The 36 channels correspond to the following modis channels:
Channels 1 & 2 correspond to bandwidths 620-670 and 841-876 nm @250 m resolution.
Channels 3-7 correspond to bandwidths 459-479, 545-565, 1230-1250, 1628-1652, and 2105-2155 nm @500 m resolution.
Channels 8-19 correspond to the reflective and Near IR bandwidths 405-420, 438-448, 483-493, 526-536, 546-556, 662-672, 673-683, 743-753, 862-877, 890-920, 931-941 and 915-965 nm @1000 m resolution.
Channels 20-36 correspond to the emmisive bandwidths 3.66-3.84, 3.92-3.98, 3.92-3.98, 4.02-4.08, 4.43-4.49, 4.48-4.54, 1.36-1.39, 6.535-6.89, 7.17-7.47, 8.40-8.70, 9.58-9.88, 10.78-11.28, 11.77-12.27, 13.18-13.48, 13.48-13.78, 13.78-14.08, 14.08-14.38 micrometers @1000 m resolution.
Valid responses are [1 through 36]. The default is 3,7,10,14,17,21,25,28,32,35. Specify 1^36 if all 36 channels need to be extracted.
Channels 13 and 14 have both high and low signal-to-noise ratios. modisin extracts both and creates a separate variable for each in the output dataset: modis_ch13H, modis_ch13L, modis_ch14H, and modis_ch14L.
This parameter specifies the rate of subsampling for the 500 meter resolution channels. If delta_500m=2, every other line and and every other sample will be used. If delta_500m=1, all lines and samples will be used.
Valid responses are [1 or 2]. The default is 1.
This parameter specifies the rate of subsampling for the 250 meter resolution channels. If delta_250m=2 every other line and every other sample will be used. If delta_250m=1, all lines and samples will be used.
Valid responses are [1, 2, or 4]. The default is 1.
This parameter specifies whether the data should be filtered for the bowtie effect caused by MODIS mirror scanning. If bowtie_filter=yes, then the pixel dispacement is calculated based on a quadratic equation defining the sensor geometry. The default is yes.
The letter 'b' is appended to output variables corrected for bowtie, thus renaming the variable (for example, modis_ch03b). The default is yes.
Answer yes if the data is to be selected from the intersection of a master dataset (number 1 in the description above; also see master). Answer no if subsets are to be specified by start time and sample (number 2 in the description above).
Valid responses are [yes, no]. The default is yes.
If use_master=yes, this is the name of the master dataset used to specify a region for data extraction (see master).
Valid responses are any TeraScan dataset that contains a map projection-based earth transform. The default is Master.
When use_master=yes, this parameter determines if output data is the full MODIS scan width, or just wide enough to cover the master file. The default is no, not full width.
This is the start time for data extraction. The first line with a time greater than start_time is the first output line. A response of 00:00:00 instructs modisin to begin processing at the first scan line.
Any valid time is allowed (see formats). The default is 00:00:00.
This is the number of MODIS detector scans to be written to the output MODIS dataset. For each 1000m channel, there are 10 detectors, and therefore 10 lines per scan. For each 500m channel, there are 20 detectors, and therefore 20 lines per scan. For each 250m channel, there are 40 detectors, and therefore 40 lines per scan. Each MODIS detector scan sweep takes about 1.477 seconds.
The valid range is [1 to 580]. The default is 580. This represents over 14 minutes of MODIS data, or roughly the longest possible MODIS overpass.
This is the first 1000m channel sample to extract from the pass. Samples are numbered starting with 1. The start sample for 500m and 250m channels is automatically computed from the 1000m start sample.
The valid range is [1 to 1354]. The default is 1.
This parameter controls the number of 1000m channel samples written to the output dataset. The number of 500m channel samples and 250m channel samples are automatically computed from the number of 1000m channel samples.
The valid range is determined by [start_sample -1 + num_samples <= 1354]. The default is 1 + 1354 - start_sample.
1. Create a TeraScan dataset named mymodisdata with all 36 channels from a MODIS level-0 PDS file.
scrum% modisin t1.00125.1928.pds mymodisdata channels : int ( 36) ? [3 7 10 14 17 21 25 28 32 35]1^36 delta_500m : int ? [1] delta_250m : int ? [1] bowtie_filter : char( 3) ? [yes] use_master : char( 3) ? [no] start_time : char( 15) ? [00:00:00] num_scans : int ? [580] start_sample : int ? [1] num_samples : int ? [1354] Pass Start: 15464 70141.453 - 1 - Day *** wcnt 0 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 10 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 20 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 30 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 40 - dt 1.477 *** seqflag 01 - samples 1354 . . . mymodisdata: 1000M_line final length 4860 mymodisdata: 500M_line final length 9720 mymodisdata: 250M_line final length 19440 Attitude( 486): R/P/Y 0.0000/0.0000/0.1290
2. Create a TeraScan dataset named modis.00306.1622 from a pass on the passdisk. Only channels 1, 3, and 4 are processed.
scrum% modisin output_file : char(255) ? modis.00306.1622 on_pass_disk : char( 3) ? [yes] pass_number : int ? [4] 3 channels : int ( 36) ? [3 7 10 14 17 21 25 28 32 35] 1 3 4 delta_500m : char( 1) ? [1] delta_250m : char( 1) ? [1] bowtie_filter : char( 3) ? [yes] use_master : char( 3) ? [no] start_time : char( 15) ? [00:00:00] num_scans : int ? [580] start_sample : int ? [1] num_samples : int ? [1354] Pass Start: 15996 67899.711 - 1021 - Day *** wcnt 0 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 10 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 20 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 30 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 40 - dt 1.477 *** seqflag 01 - samples 1354 *** wcnt 50 - dt 1.477 *** seqflag 01 - samples 1354 . . . pass-3: 500M_line final length 9740 pass-3: 250M_line final length 19480 Attitude( 487): R/P/Y 0.0000/0.0000/0.1290 CADU -to- MODIS packet processing summary Total input CADU frames processed: 1151400 Number of CADU containing MODIS data: 1071300 Number of usable MODIS packets: 1475114
MODIS_overview, Creating uncalibrated MODIS datasets, modisin processing example, IMAPP
Barnes, W.L., T.S. Pagano, and V.V. Salomonson. 1998. Pre-launch Characteristics of the Moderate Resolution Imaging Spectroradiometer (MODIS) on EOS-AM1. IEEE Transactions on Geoscience and Remote Sensing Vol. 36, 4 1088-1100.
Last Update: $Date: 2002/05/07 23:51:05 $