Abstract
Abstract. During the occurrence of floods, the government generally tries to determine the extent of the continuously changing inundation (water) area as a disaster response for planning evacuations and designing drainage systems. One of the most common methods to identify this area during the daytime involves the interpretation of aerial optical images and videos that are obtained using an airplane, helicopter, or satellite. However, these aerial approach methods have not been established convincingly for their use during the night time. Therefore, to identify the water area at night, two hand-held optical sensors were used in this study, namely: an ultrasensitive camera (Sony SL camera α7S), and a thermal infrared camera (Optris thermography PI640). The night-time aerial performance was evaluated using a helicopter, along with a supplementary night-time examination on the ground. Herein, we targeted river water areas during normal conditions. As a result, it was determined that the water area could be identified clearly with an ultrasensitive camera that has an ISO sensitivity between 51200 and 102400. The thermal infrared camera was able to identify the water area to have a higher temperature than that of the surrounding area. However, in some cases, the water area boundaries were not clear. Thus, as the thermal infrared camera was susceptible to varying conditions, supplemental use of an ultrasensitive camera was determined to be effective for the identification of inundation (water) areas at night. The significance of this study is established by the fact that the studied sensors can be easily transported in a helicopter or mounted on a UAV for night-time applications.
Highlights
Large-scale flooding has recently become frequent worldwide, and Japan is no exception
We selected an ultrasensitive camera and a thermal infrared camera as hand-held optical sensors that can be placed in a helicopter, which is relatively easy to fly during the night time; this was aimed at testing their aerial performance for detecting inundation areas at night
When the focus was changed to manual focus (MF), it was confirmed that the water area could be identified even with an ISO sensitivity of 102400
Summary
Large-scale flooding has recently become frequent worldwide, and Japan is no exception. A relatively common method to identify the inundation area during the daytime is the interpretation of the aerial optical images and videos, which are obtained using an airplane, helicopter, or satellite. There are no credible methods to identify the inundation area using the aerial approach at night. One such method uses synthetic aperture radar (SAR); the observational timings of all the major SAR satellites are approximately twice a day, with an uncertainty in the possibility of obtaining the images at night. We selected an ultrasensitive camera and a thermal infrared camera as hand-held optical sensors that can be placed in a helicopter, which is relatively easy to fly during the night time; this was aimed at testing their aerial performance for detecting inundation areas at night
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
