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MC-FUME: A new method for compositing individual reflective channels

GiL Lissens, Els Brems and Frank Veroustraete
Flemish Institute for Technological Research (Vito)
Centre for Remote Sensing and Atmospheric Processes (TAP)

Paper (pdf file, 45 k)

MC-FUME stands for Median Composite of FUzzy Multispectral Estimate. It is the name of a newly developed method for compositing individual reflective channels of the VEGETATION sensor (VGT) onboard the SPOT-4 platform. It was developed in the framework of the VGT Preparatory Programme and is based on an extensive database of model simulated TOA (Top-Of-Atmosphere) reflectance values in the BLUE, RED and NIR spectral range of the VGT instrument. Considering the atmospheric influence to be stochastic, the database is used to estimate for each pixel the TOC (Top-Of-Canopy) reflectance at a reference geometry based on the observed TOA reflectance. Taking the median of the estimated TOC reflectance values does compositing over a specific time period.

The method is tested on simulated time series at different latitudes. Its ability to correctly reproduce TOCnadir reflectance was evaluated with respect to a number of existing compositing methods. Results are encouraging.

The MC-FUME method was in a first instance also tested on real satellite images in particular on a time series of nine NOAA AVHRR images over Belgium. The results obtained with VGT images will be presented to demonstrate the plausibility of this methodology for this sensor as well. These results are compared with composites obtained with the most commonly or frequently used algorithm that is, the MVC-NDVI (Maximum Value Composite of the NDVI). For the individual reflective channels (i.e. RED and NIR), the newly developed MC-FUME algorithm produces speckle-free composite reflectance values that are independent of observation/illumination geometry at the time of measurement. It is shown by means of some simple statistics that this is not the case for the classic MVC method.

Keywords: MC-FUME, multitemporal compositing, speckle reduction, MVC-NDVI, observation/illumination geometry, VEGETATION.

Acknowledgements: We acknowledge the financial support offered by the CNES under contract N°95/CNES/0449 and the Belgian Science Policy Office under contract.SP67008.