Abstract
The next Landsat satellite, which is scheduled for launch in early 2013, will carry two instruments: the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). Significant design changes over previous Landsat instruments have been made to these sensors to potentially enhance the quality of Landsat image data. TIRS, which is the focus of this study, is a dual-band instrument that uses a push-broom style architecture to collect data. To help understand the impact of design trades during instrument build, an effort was initiated to model TIRS imagery. The Digital Imaging and Remote Sensing Image Generation (DIRSIG) tool was used to produce synthetic “on-orbit” TIRS data with detailed radiometric, geometric, and digital image characteristics. This work presents several studies that used DIRSIG simulated TIRS data to test the impact of engineering performance data on image quality in an effort to determine if the image data meet specifications or, in the event that they do not, to determine if the resulting image data are still acceptable.
Highlights
The Landsat satellite, referred to as LDCM or Landsat 8, is scheduled for launch in early 2013 and will carry two instruments
Note that because the various bands and arrays “look” forward or aft at different view angles, the parallax shifts are different for targets at different target-sensor slant paths. This means that all the appropriate acquisition geometry has to be properly modeled in Digital Imaging and Remote Sensing Image Generation (DIRSIG) to introduce the actual amount of band-to-band misregistration in the “raw” data stream sensed by the simulated system
These band-to-band registration issues are further complicated for Landsat 8 because the Operational Land Imager (OLI)
Summary
The Landsat satellite, referred to as LDCM or Landsat 8, is scheduled for launch in early 2013 and will carry two instruments. Filters are used to allow acquisition of two spectral bands (see Figure 1) In addition to these fundamental changes, TIRS uses refractive optics instead of ETM+’s reflective optics and a single full aperture radiometric calibrator and a deep space view which can be periodically introduced instead of ETM+’s dual source internal calibrator which is monitored at the beginning and end of every line of data. To better understand the impact of design trades during instrument build and test and to evaluate image processing algorithms and image quality issues in flight, an effort was initiated to model TIRS images The goal of this modeling effort is to produce synthetic data streams that have the detailed radiometric, geometric, and digital image characteristics that TIRS data will have. Data from the filtered regions on the three QWIP arrays are combined to produce an effective across-track linear imaging array of 1,850 detectors per band by discarding approximately 7 columns on either end of the line and allowing for approximately 28 columns of overlap between adjacent arrays
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