Geospatial Information Authority of Japan (GSI) provides information useful to rescue operations and reconstruction for the related organizations which intensively act against actual natural disasters. Typhoon No. 26, which atacked Izu Oshima Island on 15 and 16, October 2013, caused severe damages by debris flow due to heavy rain. GSI urgently took aerial photographs of disaster-affected areas on October 16 (oblique photos) and October 17 (vertical photos) andreleased them with their orthophotos. GSI also provided the website for a smooth provision of various geospatial information which is available to the activities related to the disaster, including results of photo-interpretation.
Japan Aerospace Exploration Agency (JAXA) detected the landslide area of the Izu-Ohshima Island by a polarimetric time-series analysis of the polarimetric Interferometric airborne L-band SAR data. This island was attacked by the Typhoon No. 26 on Oct. 16 and severely damaged by the long lasting heavy precipitations. Western center part of the island was severely landslide. JAXA flew the Pi-SAR-L2 on Oct. 22 over the island and also retrieved the Pi-SAR-L data of Aug. 30 2000 from the data archive. The correlation coefficient of the HH-VV polarization data and its time-variation over 2013 and 2000 successfully discriminated the landslide area as the surface scattering from the forested areas as the volume scattering area. In this short paper, we describe the Pi-SAR-L2 observation and its analysis.
Kokusai Kogyo Co., Ltd was entrusted from Tokyo Metropolitan Government and acquired airborne Lidar data on October 18 and October 27. The damage area of the mudflow has been visualized by ELSAMAP created from DHM (difference of DSM and DEM). Moreover, sediment volume estimation is carried out using the airborne Lidar data before and after disaster. Airborne Lidar data will be useful for the future disaster-prevention activity in Izu-Oshima.
PASCO Corporation applied the portable camera system, PALS (portable Aerialphotography and locator system), to systematically capturing a series of oblique photos covering the disaster area of Izu Oshima hit by Typhoon 27. PASCO also applied X-band SAR Images taken by TerraSAR-X to finding any topographical changes caused by typhoon. The results can be found at the corporate website.
Asia Air Survey took oblique aerial photographs of Izu Oshima surface failure area on 16th October 2013. These photos and Red Relief Image Map (RRIM) based on pre-disaster 5m DEM, as well as field survey, are helpful for disaster mapping.
This paper proposes the method which creates less hole 3D model for the information of the disaster area. This method fills the holes of a point cloud model reconstructed with the feature based reconstruction method. To fill the holes, our method uses local and small dense 3D models reconstructed with the template matching (the area based method). And our method uses the superpixel to detect the holes of the point cloud model regardless of whether their contours are closed or not. Our method also uses the homography matrix to fit the view of the images which are captured from the different positions because template matching is not robust for the change of the view between images. This method makes easy to search the corresponding points because this method limits the search range for the corresponding points. And we confirmed an effect of the proposed method through an experiment.
This study proposes the methodology of distinguishing the snow coverage area on mountains using terrestrial photography images. The pixel value of snow on the mountains in the image changes due to the effect of the slope condition. In the mountain slope condition, pixel value is lower by the effect of shadow. This paper, how to distinguish snow coverage for every slope conditions is considered, and it examined the distinction methodology of not being subject to the effect of shadow conditions. Snow coverage area distinguish accuracy in the terrestrial photography image is improved by the proposing methodology as compared to conventional methodology.
The single point positioning by single frequency receivers provides positioning results in real time. Its accuracy is about 10m. However, in non-real time usage, such as a fixed point observation, there is a possibility to improve the positioning accuracy of a single frequency receiver by using post interferometric processing. Two positioning experiments, the fixed point positioning experiment and the recorded trajectory comparison experiment of an object moving at a low speed between dual and single frequency GPS receivers, were carried out to examine the positioning accuracy of a single frequency observation and its post interferometric processing. The results of these experiments showed the positioning accuracy and repeatability were 0.09 to 0.12m and 0.02 to 0.07m respectively, in the measurements of the fixed point. And the differences of the recorded trajectories between the dual and the single frequency receivers were 0.65 and 1.18m and the standard deviations were 0.47 and 0.68m respectively, on the horizontal plane. These results suggest that the single frequency observation and its post interferometric processing using permanent GPS station data, has a sub meter positioning accuracy in the fixed point positioning and a repeatability on the horizontal plane of less than 1m on the recorded trajectory of an object moving at a low speed.
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