Recovery of Stereo Aerial Coverage from 1934 and 1938 into the Digital Era

Abstract

In the search for historic aerial photographs in the context of a coastal evolution project, the authors accessed a rare collection owned by the Lisbon Port Authority (APL). It had been flown in 1934 and 1938 by the first photogrammetric company in Portugal, Sociedade Portuguesa de Levantamentos Aéreos Limitada (SPLAL). The APL-SPLAL image collection represents a milestone for geomatics in Portugal and is testimony to the high standards of cartographic production at a time when aerial photogrammetry was still evolving as the most efficient method for topographic map production. The recovery of this image collection, together with its derivates, into a digital format was the aim of the present project. Two of the ongoing studies based on these original historic images are also outlined.