11:00 AM - 1:00 PM
[ACG45-P03] A 60cm water body map using aerial photography for Japan
Keywords:Waterbody, High spatial resolution, RGB, Aerial photography, Bayesian inference, Hydrography
We employed a Bayesian inference to estimate water probability using the 60 cm resolution aerial photography and approximately 10 m to 30 m resolution water fraction by Landsat-based dataset “G1WBM” and geospatial dataset as prior probabilities of water. Also, the hydrography dataset “J-FlwDir” was combined as topographical information to separate objects with the same color as the water surface from the water body. Firstly, RGB information from the aerial photography was transformed into Hue-Saturation-Value (HSV) color-space. Secondly, each pixel of aerial photography was classified mainly based on this HSV color-space and used as a condition of the Bayesian inference. Consequently, the probability of water was calculated for each classified pixel. Our method enables us to detect small rivers not seen by the previous Landsat-based 30m water body map. Rivers located in open space and not covered by vegetation or other objects can be detected well. However, there remain false alarms mainly from vegetation. Further improvement of this issue is necessary. Ultimately, river width can be calculated using the developed 60 cm waterbody map and flow direction map.