Mapping landforms - Aerial Photographic Interpretation

Interpretation of stereo-paired aerial photographs probably is one of the most useful tools to the geomorphologist in the office. Traditionally this has been accomplished by putting a transparent overlay on the photos (0.3mm acetate working best) and using a stereoscope to map contacts and surfaces. I usually use different colored pencils and colored lead in mechanical pencils (red and blue 0.5mm leads). The mapping on the overlays then needs to be transferred, usually to a USGS topographic map.

By photocopying the air photo overlay and enlarging or reducing it to fit the map scale, I then transfer the information to the base map. Often during this process, the mapping changes as the topographic contours on the map provides additional information on the geomorphic contacts and extent of surfaces. A good writeup of how this approach works using more modern tools is given for shoreline mapping below.

Coastline Mapping in Texas

So much has changed with GIS and the ability to combine multiple layers of information but I still rely on the stereoscope, although I can no longer easily find 0.3 mm acetate...