Spatial response of the EO-1 Advanced Land Imager (ALI)

In this paper, we characterize the spatial response of the NASA EO-1 Advanced Land Imager (ALI) sensor, a testbed for potential technologies for the Landsat Data Continuity Mission. The spatial response is measured by analysis of suitable targets in on-orbit imagery. The targets include berms between agricultural fields at the Maricopa Agricultural Center (MAC), Arizona, acquired on July 27, 2001, and the Lake Pontchartrain Causeway, Louisiana, acquired on September 20, 2001. Both targets are oriented at small angles to the ALI in- and cross-track directions. Combining data from adjoining rows or columns thus forms a new profile with a subpixel interval across the target and permits spatial frequency analysis free of aliasing. Using this approach, the ALI Line Spread Functions (LSFs), in-track and cross-track, are measured and the corresponding Modulation Transfer Functions (MTFs) are calculated for all bands of ALI. The results of the Pontchartrain analysis of the ALI panchromatic band are compared to published results for the ETM+ panchromatic band.