The Agisoft Photoscan software was used to orientate the images, extract point clouds, build a digital surface model and produce orthoimage mosaics.
The processing, which includes automatic aerial triangulation with camera calibration and subsequent model generation, was mostly automated.
To achieve the best positional accuracy for the whole process, signalised ground control points were surveyed with a differential GPS receiver.
Two very sensitive test areas on the Portuguese northwest coast were analysed.
Detailed DSMs were obtained with 10 cm grid spacing and vertical accuracy (RMS) ranging from 3.5 to 5.0 cm, which is very similar to the image ground resolution (3.2–4.5 cm).