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The Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) are two new sensors being developed
by the Landsat Data Continuity Mission (LDCM) that will extend over 35 years of archived Landsat data. In
a departure from the whiskbroom design used by all previous generations of Landsat, the LDCM system will
employ a pushbroom technology. Although the newly adopted modular array, pushbroom architecture has several
advantages over the previous whiskbroom design, registration of the multi-spectral data products is a concern.
In this paper, the Digital Imaging and Remote Sensing Image Generation (DIRSIG) tool was used to simulate
an LDCM collection, which gives the team access to data that would not otherwise be available prior to launch.
The DIRSIG model was used to simulate the two-instrument LDCM payload in order to study the geometric
and radiometric impacts of the sensor design on the proposed processing chain. The Lake Tahoe area located
in eastern California was chosen for this work because of its dramatic change in elevation, which was ideal for
studying the geometric effects of the new Landsat sensor design. Multi-modal datasets were used to create the
Lake Tahoe site model for use in DIRSIG. National Elevation Dataset (NED) data were used to create the digital
elevation map (DEM) required by DIRSIG, QuickBird data were used to identify different material classes in the
scene, and ASTER and Hyperion spectral data were used to assign radiometric properties to those classes. In
order to model a realistic Landsat orbit in these simulations, orbital parameters were obtained from a Landsat 7
two-line element set and propagated with the SGP4 orbital position model. Line-of-sight vectors defining how
the individual detector elements of the OLI and TIRS instruments project through the optics were measured and
provided by NASA. Additionally, the relative spectral response functions for the 9 bands of OLI and the 2 bands
of TIRS were measured and provided by NASA. The instruments were offset on the virtual satellite and data
recorders used to generate ephemeris data for downstream processing. Finally, potential platform jitter spectra
were measured and provided by NASA and incorporated into the simulations. Simulated imagery generated by
the model was incrementally provided to the rest of the LDCM team in a spiral development cycle to constantly
refine the simulations.
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