ausblenden:
Schlagwörter:
Lava dome, Shiveluch Volcano, Photogrammetry, Eruption, Flank instability, science > natural science > earth science > geology > volcanology
Zusammenfassung:
Here we present a photogrammetric dataset on the 2018-2019 eruption episode at Shiveluch Volcano, one of the most active volcanoes in Kamchatka Peninsula. The data were acquired by optical sensors and complemented by thermal sensors. The optical satellite images were tri-stereo panchromatic 1-m resolution imagery acquired on 18 July 2018 with Pléiades satellite PHR1B sensor. We processed the data in Erdas Imagine 2015 v15.1. For the relative orientation of the images, 37 tie points were calculated automatically with further manual correction, and for the interior and exterior orientation, Rational Polynomial Coefficients block adjustment, which is a transformation between pixels to latitude, longitude, and height information, was automatically employed. After the image orientation, we obtained a photogrammetric model with a total root mean square error (RMSE) of 0.2 m. By using the Enhanced Automatic Terrain Extraction module (eATE) with normalized cross correlation algorithm as implemented in the Erdas Imagine software, we were able to extract a 2 m resolution point cloud (PC) referenced to the WGS84 coordinate system UTM57 zone. This PC was filtered with the CloudCompare v2.9.1 noise filter and then manually cleaned with the CloudCompare segmentation tool. As strong volcanic steam emissions caused a large gap in the PC at the NE part of the dome, we used a 5 m resolution DEM constructed from TanDEM-X data to fill the gap and obtain the missing topography.
TanDEM-X is a bistatic SAR mission, formed by adding a second, almost identical spacecraft, to TerraSAR-X. Therefore, it allows the acquisition of two simultaneous SAR imageries over the same area, eliminating possible temporal decorrelations between them and maintaining a normal baseline between 250 and 500 m, which is suitable for SAR interferometry for DEM generation. We used the interferometric module in ENVI SARscape to build the interferogram, perform the unwrapping step and finally convert it into height information using forward transformation from radar to geographic coordinates. The RMSE of the generated DEM is evaluated based on the coherence value, i.e. quality of the interferogram, and is estimated to be approximately 5 m.
