In order to acquire geographical data by aerial photogrammetry, many images should be taken from an aerial vehicle. After that, the images are processed with the help of the structure-from-motion (SfM) technique. Multiple neighboring images with a high rate of overlapping should be obtained for high-accuracy measurement. In the event of natural disasters, UAV operation may sometimes involve risk and should be avoided. Therefore, an easy and convenient method of operating the UAVs is needed. Reports exist on some applications of the UAVs with other devices; however, it will be difficult to prepare a number of such devices in emergency. We considered the most suitable condition for image acquisition by using the UAV. Specifically, some of the altitudes and the rate of overlapping were attempted, and accuracies of the 3D measurement were confirmed. Furthermore, we developed a new camera calibration and measurement method that requires only a few images taken in a simple UAV flight. The UAV in this method was flied vertically and the images were taken at a different altitude. As a result, the plane and height accuracy was ±0.093 and ±0.166 m, respectively. These values were of higher accuracy than the results of the usual SfM software.
Planners, designers, governmental organizations, and citizens are interested in creating enduring safe buildable environments. Landscape hazards such as earthquakes, wildfires, hurricanes, tornados, flooding, volcanoes, radon, air pollution, sinkholes, avalanche, landslides, and blizzards create a complex set of destructive forces that form disturbances obliterating life and structures. In our study, we examined these forces across the lower 48 states of the United States of America. We applied geographic information system (GIS) technology to identify areas of extreme hazard and areas of low risk. Our investigation indicated that most of our study area (approximately 83%) was exposed to highly reoccurring destructive forces and that only relatively small patches (Upper Midwest-portions of Michigan, Wisconsin, and Minnesota) and thin stretches (Rocky Mountain Front Range—eastern Montana, Wyoming, and eastern Colorado) of land were relatively secure from these forces. This means that in the long term, much of the study area is not safe from disturbances that will destroy much of the built environment, challenging notions of sustainability for numerous metropolitan areas, United Nations Educational, Scientific, and Cultural Organization (UNESCO) Biosphere Reserves, UNESCO World Heritage Sites, National Parks, other noted historic sites.
Part of the book: Landscape Architecture