Map and Aerial Photo Interpretation
Maps have long played an important role in society. The advent of aerial and satellite photography has allowed mankind to soar with the birds and observe their surroundings from a lofty vantage. Viewing our built environment from such heights provides different context than what can be observed at ground level. Nowadays aerial imagery has the ability to transport the observer to faraway places from the comfort of their personal computer. The desire to extract more detailed information from aerial photos is unrelenting. The application of newer technologies such as light detention and ranging (LiDAR), spectral imaging, and geo-referencing have taken the art and science of aerial photography and processing to new levels.
Military applications of aerial photography/cartography are well known. Cartographers were sent aloft in hot air balloons during the Civil War to sketch troop positions. During World War 1 cameras were strapped to bi-planes in an effort to survey the battlefield. In World War 2 cameras flew along during bombing raids to provide battle damage assessments. Reconnaissance photos provided valuable intelligence in advance of missions. During the Cold War spy planes flew higher than ever to evade enemy missiles. Camera technology kept pace and provided better and better resolution photos. Satellites now have the ability to take photos of the Earth’s surface with sixteen inch resolution from 423 miles up.
Many of these technologies have trickled down to provide the public with access to aerial images and analysis tools. Google Earth is the ubiquitous aerial imagery tool used by millions that has brought about a renaissance in geographic thinking in the past few decades. Similar to the military's trajectory the public has sought better resolution. In the past 25 years the availability of high resolution color aerial images is freely available allowing anyone to gain a better understanding of their surroundings. A key to successful aerial photo interpretation relies upon knowledge of the ground truth. For example in order to determine what a feature looks like on an aerial image one must first know what that feature looks like in real life. Cuyahoga SWCD uses Google Earth and other products extensively to track changes in land use over time, identify water resources, measure properties, and much more.
Most recently Cuyahoga has used aerial photography to gain a better understanding of the water resources present on a proposed development site. Identifying those water resources from an aerial image available on the web saved time and staff resources. Furthermore it allowed our staff to provide timely and accurate plan review comments thereby saving the developer unnecessary delays.
Currently aerial images do not completely erase the need for good field work, although remote sensing comes close. Much like in WWII a good aerial photo reconnaissance in advance of a plan review or field work provides valuable context and insight to help to better accomplish the job.
Blog Author: Brent Eysenbach, Senior Program Manager