LANL experience with coregistration of MTI imagery

The fifteen-channel Multispectral Thermal Imager (MTI) provides accurately calibrated satellite imagery for a variety of scientific and programmatic purposes. To be useful, the calibrated pixels from the individual detectors on the focal plane of this pushbroom sensor must be resampled to a regular grid corresponding to the observed scene on the ground. In the LEVEL1B_R_COREG product, it is required that the pixels from different spectral bands and from different sensor chip assemblies all be coregistered to the same grid. For the LEVEL1B_R_GEO product, it is further required that this grid be georeferenced to the Universal Transverse Mercator coordinate system. It is important that an accurate registration is achieved, because most of the higher level products (e.g. ground reflectance) are derived from these LEVEL1B_R products. Initially, a single direct georeferencing approach was pursued for performing the coregistration task. Although this continues to be the primary algorithm for our automated pipeline registration, we found it advantageous to pursue alternative approaches as well. This paper surveys these approaches, and offers lessons learned during the three years we have been addressing the coregistration requirements for MTI imagery at the Los Alamos National Laboratory (LANL).