Fast coastal algorithm for automatic geometric correction of AVHRR images

A coastal algorithm for fully automatic geometric correction of Advanced Ve ry High Resolution Radiometer (AVHRR) images is presented. Inputs are the A VHRR image and updated ephemeris data and outputs are the georeference imag e and a cloud image mask. Its principal advantage and novelty is that it re quires only manual control in the first stage of the process. Particularly, the detection of Ground Control Points (GCPs), usually rather time consumi ng, is performed with this method in an automatic way. The procedure only r equires the previous existence of a coastal referernce-windows database. To find the exact location of the GCPs, the routine searches the best match o f these reference-windows with the image. The complete automation of the pr ocess makes the routine very fast, then allowing its operative application on a large volume of images. The process provides accuracies to within 1-1. 5 AVHRR pixels.