526 
Function are scene correction data in the form of 
perturbations to the nominal horizontal resampling 
(HRS), vertical resampling (VRS) correction matrices 
stored in the MIPS. The output of the TM Payload 
Correction Function is à set of 25 correction 
matrices for each scene, two of which are high 
frequency matrices that provide corrections for the 
effects of jitter and TM scan mirror.and scan line 
corrector nonlinearity on a scan:basis, Figure 12 
summarizes the content of these matrices. 
Archive Generation. These functions are analogous 
for TM and MSS in that each ingests raw video 
(HDTR) and outputs archival data (HDTp) that 
have been radiometrically corrected and has the 
geometric correction data appended. The 
dissimilarity is in the methodology of the process, 
the processing rates and the special purpose 
hardware required for TM. 
  
MSS archive generation is a buffered process. Raw 
video data (HDTR), up to a maximum of 
approximately 35 scenes, are ingested and stored on 
disc. A data extraction and calculation phase is 
executed. Upon completion, the MSS data are 
radiometrically corrected, ancillary (geometric 
correction) and annotation data are appended and 
output from disc to the archival product (HDTa). 
The ingest and output process for MSS executes at 
. 1/4 MSS real time ( =~ 4Mbps). The complete MSS 
archive generation process takes between 6 and 7 
minutes per scene. 
TM archive generation is a staged pipeline process. 
The first stage is an ingest/data extraction phase 
where only selected portions of the raw scene data 
are ingested (calibration lamp data, control point 
neighborhoods, etc.). The second stage is a 
calculation phase. The third stage is an output 
phase, but is a pipeline process in that raw TM 
video are being ingested (HDTR) and 
radiometrically corrected archival data, with 
ancillary and annotation data appended, are being 
output (HDTp) simultaneously. A key feature of 
this process is that the video data never enter the 
computer bus. The interface device is a high speed 
array processor that also acts as a scan buffer and 
provides alternate scan reversal and reformatting 
for TM data. This allows the pipeline ingest/output 
process toiexecute at 1/2 TM real time ( = 42 
Mbps). The complete TM archival generation process 
takes between 4 and 5 minutes per scene. Another 
key contributor to the processing speed is the 
special purpose hardware developed to synchronize, 
demultiplex, extract, buffer and reformat the high 
rate TM video.