| The Modulation Transfer Function (MTF) is a standard measure of imaging systems performance. This work addresses determination of the MTF for the Moderate Resolution Imaging Spectroradiometer (MODIS) Earth remote sensing system on NASA's TERRA satellite. Reliable characterization of the MODIS MTF requires using as many sources of information as possible for evaluation. In this research a model, pre-launch and on-orbit measurements are used to develop a consistent characterization of the MTF. The on-orbit characterization is implemented using two approaches. The first is cross-track temporal monitoring using data derived from the SpectroRadiometric Calibration Assembly (SRCA). The second is using a two-image approach in which the reference is Landsat-7 Enhanced Thematic Mapper (ETM+) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). This characterization of the MTF is used to evaluate the effect on science products, the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI), and includes partial MTF correction (MTFc) as a way to improve the accuracy. This work has produced the following significant results: (1) A model for the pre-launch MODIS MTF. (2) Automatic image registration using the geolocation data. (3) Cross-track on-orbit MTF are comparable to the pre-launch MTF for bands 1, 2, 6 and 29. (4) In-track on-orbit MTF indicate that it is lower for bands 1 and 2 (in most cases), and comparable for bands 6 and 29, in reference to the pre-launch MTF. |
