Pelleter des nuages

An important issue to be tackled concerning the mapping of Borneo is what to do with the clouds. Borneo is largely covered by rainforest so there are quite a lot of them obstructing the view. So what can be done? I’ll just free style a couple of options here (not all of them are feasible or practical.) Ideally, it would be great to erase all of them. This said, because some of these clouds are quite thick, I’m doubtful even a sophisticated ATCOR algorithm would see through them. Also, I don’t believe it would be relevant to use such an elaborate algorithm here. For one thing, we don’t have information available to use ATCOR reliably. This said, we still need to take into account the atmospheric interference. A more basic approach, using a SMAC like algorithm for instance, would be more suited (ex.: Production of CORINE2000 Land cover data using calibrated LANDSAT 7 ETM satellite image mosaics and digital maps in Finland .) Another way of getting rid of clouds is by comparing multiple images pixel by pixel and keeping the “best” ones. The challenge then becomes finding numerous images of the same areas, ideally taken over a relatively short time frame. In the end, we might have to completely give up on certain areas and concentrate on what we can work with.

On another somewhat related note, I’ve found a new source of data where we have all the bands of the LANDSAT images. Also, the metadata provided enables us to know when each image was taken so we can better take into account both the angle of the satellite and of the sun, something which will turn out quite useful to enhance our images, especially in conjunction with the DEM.