ON-BOARD MULTISPECTRAL ALIGNMENT FOR IMPROVED CLASSIFICATION AND COMPRESSION RESULTS

摘要

In the future the significance of on -board processing of acquired images will increase. The reason isrnless a changed objective in the user community but rather the rising impact of engineering limitations.rnProminent exam ples are given by micro-, mini-, and small-satellites that are currently gaining inrnpopularity. One of the most substantial implications in the design of these satellites is a limited downlinkrnbandwidth for various reasons, e.g. a restricted power budget and / or a small number of ground receivingrnstations. Therefore on-board processing becomes almost mandatory since it enables thernutilisation of the raw imagery and reduces the amount of data by computing high-level products, whichrnthen again eases the requirements on the communication link. The advan tages of this approach arernpre -dominant for highly specialised missions. However, even for general imaging missions on-boardrnprocessing can provide additional benefits. This paper illustrates the gains of on-board processing byrnchoosing multispectral alignment as a demonstrating application. The multispectral band-to-band alignmentrnis one key factor in remote sensing and a mismatch between the different spectral bandsrninevitably leads to de creased accuracy for every application that makes explicitly use of the spectralrninformation. The causes for the displacement are mainly determ ined by the design of the acquisitionrnunit, i.e. the arrangement of the charge coupled devices. This paper proposes a technique to measurernthe actual displacement. Subsequently the multispectral scenes are aligned using a parallel processingrnunit that is currently developed for the mini-satellite mission X-Sat. The results show that satelliternmissions profit by the on -board alignment since the data reliability is improved. This is of major interestrnfor any further processing of the image data, which will continuously be pushed towards space over thernnext few years.