Orthorectification of historic aerial photos
Updated Dec 14 2020 One of the occasional tasks I undertake in my geological mapping work is to orthorectify historic vertical aerial photos in order to examine them in a GIS. The old photos have much value as they capture the landscape at particular point in time where it may have been subsequently modified. I have recently been working in the Launceston area and have created mosaics of the oldest and most detailed photos available in order to show extent of older quarries, geomorphic features, geology, etc. As an example, I was recently asked to comment on a development application on a former quarry site and the old photos were very good at showing the extent of ground disturbance. I created a digital stereopair with StereoPhotomaker (see earlier blog) from the scans and made a rectified image for the GIS from which I was able to gain a good understanding of the site. This blog provides a documented methodology for my own benefit and anyone else. There are two main consid...