Frey, Corinne Myrtha and Parlow, Eberhard. (2009) Measurement of multispectral BRF effects of the megacity Cairo, Egypt, using CHRIS/PROBA data. In: Remote Sensing for a Changing Europe - Proceedings of the 28th Symposium of the European Association of Remote Sensing Laboratories, Istanbul, Turkey, 2-5 June 2008. Amsterdam, pp. 594-601.
In this analysis, a series of images from the ESA imaging spectrometer CHRIS on the technology demonstration satellite PROBA, taken in a row over Cairo on 17th February 2007 and 24th March 2008 at each five different viewing zenith and azimuth angles are analyzed to find the BRF (bidirectional reflection function) which is typical for urban areas in a developing Arab country. The results are only valid for these sun-sensor constellations, since only two scenes were analyzed. CHRIS/PROBA features 18 bands in the shortwave range. All bands were first destriped and then corrected for atmospheric influences using the radiative transfer model MODTRAN. Furthermore the images were geo-referenced using manually set pass points. The accuracy of the geolocation varies across the image. Generally pixels match well; however, in some areas there is a shift of one or two pixels. There is a clear dependency in the reflectances on the viewing geometry of the sensor. The regression coefficients r2 from the regression between the reflectance and the viewing geometry are high for all bands in all urban areas. No distinct difference was found for high or medium dense housing.