What Makes Oblique Imagery So Effective for Disaster Response?
Over the past decade there have been many devastating natural disasters throughout North America, including hurricanes, floods, earthquakes and wildfires that have caused lasting geographic changes. As a result, updated maps have been created from data collected by satellites, fixed wing aircraft, helicopters and terrestrial scanners. New and improved technology is always being introduced to provide better geospatial information, and high resolution oblique imagery is gaining traction as an extremely useful tool to assist with emergency response, damage assessment and reconstruction planning.
Oblique imagery is collected at approximately 45 degrees from low-flying aircraft. Every side of a building or object is viewable in the imagery, and height, distance, altitude and surface area can be measured directly on the images. GIS layers, such as addresses, medical facilities, schools and transportation routes, are geo-referenced with the images to provide usable information for first responders on mobile devices or laptops in the field. These characteristics, along with a quick turnaround for collecting, processing and distributing data, make oblique imagery highly suitable for emergency situations.
Pictometry International Corp., a geospatial solution provider based in Rochester, N.Y., has extensive experience collecting oblique and nadir imagery with its fleet of aircraft and patented aerial cameras. “Pictometry feels strongly that it is our civic responsibility to help in any way possible when there is a natural disaster,” says Frank Giuffrida, senior vice president engineering. “In the case of Hurricane Sandy, we flew 300 miles of coastline between Montauk Point, New York, and Cape May, New Jersey, and 600 square miles of inland areas, and had usable imagery available online through Pictometry Connect within 48 hours of data capture. Pictometry Connect is our cloud service that contains historical imagery, the new post-hurricane photographs, and clients’ GIS data to allow before and after comparisons, damage analysis, and claim forecasting. Commitment to our clients is a top priority, and it was vital to have new imagery before the Nor’easter hit just a few days after the hurricane to be able to differentiate between water and wind damage.”
The fast turnaround after Hurricane Sandy was made possible by Pictometry’s access to a large number of aircraft. To meet the deadline, eight light aircraft were deployed to the area, out of over 70 that are available to the company.
Almost every county impacted by Hurricane Sandy was utilizing imagery from Pictometry prior to the storm, so the “before” imagery was already online. In 2001, Pictometry captured the New York/New Jersey area after the terrorist attack on the World Trade Center, and it has reflown portions of these areas several times since. The rich database provides great value for a variety of applications. “So much more relevant detail is available in an oblique image than in a straight-down ortho shot,” says Giuffrida. “What used to be a niche market is now fairly standard in the mapping community. Each and every pixel is geo-referenced, which is key, because in situations such as Sandy, responders are able to accurately determine which areas have been hit the hardest, which houses are most affected, and where there might be survivors.”
Pictometry started its business in 2000 by focusing on county projects, specifically for the public safety sector. Now, after a dozen years of educating the public on the numerous applications of oblique imagery and derivative products, Pictometry is frequently called upon to serve clients in other industries, such as insurance, utilities, oil and gas, tax assessment, and construction. For example, insurance carriers use before and after oblique images to assess damage and process claims, particularly in areas that are too dangerous for ground inspections, while utilities find oblique imagery useful for monitoring power lines and telephone poles, inspecting buildings and transformers, and assessing damage and planning repairs. In some situations, such as search and rescue, Pictometry offers Real Time Airborne Management System (RAMS) products, where data is processed on the airplane and either downlinked to the ground with only a 15-second delay, or accessed as soon as the plane lands, within a few hours of data capture. Extensive training in photo interpretation is not required to make use of oblique imagery because it is fairly intuitive; the image looks the way it does in real life.
Part of the growth in demand for oblique imagery can be attributed to an increasing interest in 3D modeling. Consumers have come to expect access to realistic and accurate 3D data of their cities and towns, tourist attractions, college campuses, and any place found on a map. Emergency responders rely on 3D solutions, too. From mobile devices in the field, or a laptop in the squad car, 3D increases situational awareness, which supports better decision making. “Think about having the ability to pluck a home off of a map and pull it apart in a three dimensional manner—the sides, roof, and layers of the home—and calculate the area, height, width, and distance of each piece,” explains Giuffrida. “Oblique imagery provides this level of fidelity for the creation of a 3D model, and overall provides another layer of usable information that can help people do their jobs better.”