LiDAR and UAV SfM-MVS of Merapi Volcanic Dome and Crater Rim Change from 2012 to 2014

Abstract

Spatial approaches, based on the deformation measurement of volcanic domes and crater rims, is key in evaluating the activity of a volcano, such as Merapi Volcano, where associated disaster risk regularly takes lives. Within this framework, this study aims to detect localized topographic change in the summit area that has occurred concomitantly with the dome growth and explosion reported. The methodology was focused on two sets of data, one LiDAR-based dataset from 2012 and one UAV dataset from 2014. The results show that during the period 2012–2014, the crater walls were 100–120 m above the crater floor at its maximum (from the north to the east–southeast sector), while the west and north sectors present a topographic range of 40–80 m. During the period 2012–2014, the evolution of the crater rim around the dome was generally stable (no large collapse). The opening of a new vent on the surface of the dome has displaced an equivalent volume of 2.04 × 104 m3, corresponding to a maximum −9 m (+/−0.9 m) vertically. The exploded material has partly fallen within the crater, increasing the accumulated loose material while leaving “hollows” where the vents are located, although the potential presence of debris inside these vents made it difficult to determine the exact size of these openings. Despite a measure of the error from the two DEMs, adding a previously published dataset shows further discrepancies, suggesting that there is also a technical need to develop point-cloud technologies for active volcanic craters.

MVP-Stereo: A Parallel Multi-View Patchmatch Stereo Method with Dilation Matching for Photogrammetric Application

“…Unlike other stereo estimation methods that rely on the front-parallel assumption [40], patchmatch stereo defines a slanted plane for each pixel p i using three parameters a f p i , b f p i , c f p i to calculate the matched pixel p j , as shown in Equation (2), where x p i , y p i is the position of p i on the image plane.…”

“…Three dimensional reconstruction based on RGB images is more convenient and less costly compared to RGB-D sensors and lasers, and has a very wide range of applications in various industries [1][2][3], laying the foundation for 3D perception [4][5][6][7][8]. Generally, the 3D reconstruction pipeline includes structure from motion (SfM) [9,10], multi-view stereo (MVS) [11][12][13][14][15][16][17], mesh reconstruction [18][19][20][21][22] and texture mapping [23], where MVS tries to obtain correspondence between pixels on images to reconstruct a dense 3D point cloud.…”

Deception Island 1967–1970 Volcano Eruptions from Historical Aerial Frames and Satellite Imagery (Antarctic Peninsula)

“…It has been of particular interest to study volcanic geomorphology based on photogrammetry, recovering historical aerial frames taken both vertically and obliquely to the Earth surface [34][35][36]. Furthermore, unmanned aerial vehicles added particular interest to photographic data in the real-time study of the evolution of eruptions [37,38].…”

Rainfall-induced Gravity Movement of the Unzen-Fugendake Volcanic Dome Analysis combining Ground-Radar Interferometry and XRAIN Rainfall radar system

“…road marking [4]), because of their gravitational collapse during eruption, triggering pyroclastic-flows, and because of the domes' explosions that can propel ash and scoria high in the upper-atmosphere, and thus affect large areas under the wind as well as international air-traffic. As a rule of thumb, in the aftermath of eruptions, internal pressure at the dome decreases and the risk of dome explosion reduces, even if non-eruptive phreatic and phreatomagmatic explosion can still occur, like it did between 2012 and 2014 at Merapi Volcano [5]. Furthermore, volcanic domes tend to grow and "break-down" during eruptions, with only small domes (gravitationally stable) or virtually none remaining in between eruptions.…”