1. 1ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The Landsat 7 Processing System ( LPS ) Level Zero-R Science Products Michael R. Reid Computer Sciences Corporation Mike.Reid@gsfc.nasa.gov

2. 2ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The Landsat 7 Mission The latest in the Landsat series Joint operation between NASA and USGS Global coverage in 8 bands Sun-synchronous orbit Landsat 7 successfully launched in April 1999 Now fully operational Data products provided by the USGS’ EROS Data Center (EDC) in Sioux Falls, SD

3. 3ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Earth Coverage Enhanced Thematic Mapper Plus (ETM+) is the only science instrument –Images the Earth in 185 km wide swaths –Images in eight bands Image data are fitted onto the Worldwide Reference System (WRS) grid –WRS grid consists of 185 km  170 km scenes –ETM+ images a WRS scene with 375 scans WRS scenes overlap

4. 4ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The ETM+ Instrument Data Eight bands –Six 30m-resolution spectral bands Bands 1-5 (range = 0.45…1.75  m) Band 7 ( = 2.09-2.35  m) 6,600 pixels per scan data line 16 data lines per scan –One 60m-resolution thermal band Band 6 ( = 10.4-12.5  m) 3,300 pixels per scan data line 8 data lines per scan –One 15m-resolution panchromatic band Band 8 ( = 0.52-0.90  m) 13,200 pixels per data line 32 data lines per scan

5. 5ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Landsat 7 Processing System (LPS) Developed at NASA/GSFC for the EDC Part of the Landsat 7 Ground System Performs the first stage of Level 0 processing –Aligns bands (forward and reverse scans) –Does not apply corrections or calibrations –Does not perform rectification Produces HDF-EOS science data products on a subinterval basis Runs on a high-end SGI ™ system

6. 6ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 LPS Processing Divides the subintervals into sets of contiguous WRS scenes Geolocates the scenes Produces viewable, multi-band, color browse images on a WRS scene basis Performs automatic cloud cover assessment (ACCA) on a WRS scene basis Displays a Moving Window Display to the user

7. 7ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The LPS Moving Window Display (MWD)

8. 8ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 LPS Processing continued… Receives data on two channels (“format 1” and “format 2”) Decodes the downlinked raw telemetry Processes the two formats separately Constructs an image in each band of the “swath” on the Earth’s surface covered during a contact Divides the swath into subintervals

9. 9ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The LPS Data Products LPS products generated on a subinterval basis Format 1 and Format 2 are separate file sets The LPS Product file sets include: –Band files (Swath files) –Internal Calibrator (IC) data files –Mirror Scan Correction Data (MSCD) files –Payload Correction Data (PCD) files –Metadata files –Multi-Band Browse files (format 1 only)

10. 10ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The Band Files — Swaths Image data stored in HDF-EOS Swaths –One Swath per file Bands 1-5 & 7 files are up to about 1.2 Gb in size Band 6 files are up to about 295 Mb in size Band 8 data are huge, won’t fit in single files –Up to about 4.6 Gb of data in a 35-scene subinterval –HDF 4 limits file sizes to 2 Gb –Written to up to three separate swaths in separate segment files

11. 11ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The Band Files — Geolocation Geolocation structures –Uses HDF-EOS Index map to link WRS scene corner lon/lat coordinates to the Swath Full scenes from 30m-res. bands are always 6,000 data lines Partial scenes at the beginnings and ends of subintervals are of irregular sizes –Uses Time Geolocation field to temporally locate scans in the Swaths HDF-EOS Geolocation structures also used to store other ancillary data

12. 12ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The Internal Calibrator (IC) Files Contain lamp and shutter data for spectral bands Contain blackbody radiance and shutter data for thermal band (band 6) One file for each format –Separate HDF-EOS Swath for each band One data set per scan Data located by Time only using HDF-EOS Geolocation structure

13. 13ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Mirror Scan Correction Data (MSCD) Files Mainly contain data quality information Stored in an HDF-EOS Point Located by Time only using HDF-EOS Geolocation structure Format 1 and Format 2 MCSD are identical except for start and end offsets at the beginnings and ends of the data

14. 14ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Other LPS Product Files Payload Correction Data (PCD) Files –Contain spacecraft attitude and ephemeris information and miscellaneous engineering data –Native HDF Vdata, no HDF-EOS structures –Format 1 and Format 2 are identical Metadata Files –Format 1 and Format 2 similar, but not identical –Simple text file in Object Definition Language (ODL) Syntax Browse Files –Format 1 only –One native HDF RIS24 true color image –Made from three of the five format 1 spectral bands –JPEG Compressed images

15. 15ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 LPS Browse File (Hudson Bay)

16. 16ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Format 1 Six Band files –Bands 1-5 and 6L One Internal Calibrator (IC) data file One Payload Correction Data (PCD) file One Mirror Scan Correction Data (MSCD) file One Metadata file –Includes scene cloud cover assessments 1 to 37 Multi-band Browse files

17. 17ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Format 2 Three Bands, up to five files –Bands 6H and 7 –Band 8 (High-Resolution Panchromatic Band) Written to up to three segment files due to size One Internal Calibrator (IC) data file One Payload Correction Data (PCD) file One Mirror Scan Correction Data (MSCD) file One Metadata file No Browse files

18. 18ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 The LPS Product File Set

19. 19ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Level Zero-R Data Subsets Single WRS scene products –One 375 scan subset –Data fitted to the WRS grid Multiple scene products –Contains several contiguous WRS scenes Partial subinterval (a.k.a., floating scene) products –Similar to the multiple scene products, but not aligned along WRS rows Full subinterval products –Essentially the full LPS subinterval

20. 20ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Subsetting the LPS Subintervals LPS Band and IC files contain geolocated HDF-EOS Swaths –Can subset band data by index-mapped WRS scene corner geographic coordinates or time using HDF-EOS functions Band 8 presents a problem due to file segmentation –Can subset IC data by time using HDF-EOS functions MSCD file contains an HDF-EOS Point –Can subset by time using HDF-EOS functions PCD is native HDF and cannot be subsetted using HDF-EOS functions

21. 21ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 LPS Subsetting Difficulties Band data Swaths are stored in separate files Format 1/Format 2 data offset Partial subinterval geolocation –LPS only computes lon/lat coordinates for WRS scene corners, not on a scan basis –Must interpolate subset interval corner coordinates Band 8 segmentation –HDF-EOS does not support file segmentation

22. 22ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Band 8 Subsetting Problem Must treat the band 8 segments as completely separate data sets Subsetting out multiple scene or partial subinterval products from band 8 is especially complicated if the subset interval spans across segments After subsetting from the two segments, the data must be concatenated into a single array

23. 23ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 Level Zero-R Distribution Product Native HDF, no HDF-EOS structures Contains data from both Format 1 and Format 2 Subsets of Band and IC data written to Scientific Data Sets (SDS) Subset of MSCD written to Vdatas Complete PCD and Metadatas written to Vdatas Contains Calibration Parameter File (CPF) Stores all data in HDF external elements

24. 24ESDIS HDF-EOS Workshop IV Landover, Maryland, September 20, 2000 L0R Distribution Product File Set