Targeted High-Resolution Structure from Motion Observations over the Mw 6.4 and 7.1 Ruptures of the Ridgecrest Earthquake Sequence

2020 ◽  
Vol 91 (4) ◽  
pp. 2087-2095 ◽  
Author(s):  
Andrea Donnellan ◽  
Gregory Lyzenga ◽  
Adnan Ansar ◽  
Christine Goulet ◽  
Jun Wang ◽  
...  
Keyword(s):  
High Resolution ◽  
Structure From Motion ◽  
Earthquake Sequence ◽  
Ground Sample ◽  
High Resolution Imagery ◽  
Dirt Road ◽  
Before And After ◽  
High Resolution Structure ◽  
Aerial Systems ◽  
Conjugate Fault

Abstract We carried out six targeted structure from motion surveys using small uninhabited aerial systems over the Mw 6.4 and 7.1 ruptures of the Ridgecrest earthquake sequence in the first three months after the events. The surveys cover approximately 500 × 500 m areas just south of Highway 178 with an average ground sample distance of 1.5 cm. The first survey took place five days after the Mw 6.4 foreshock on 9 July 2019. The final survey took place on 27 September 2019. The time between surveys increased over time, with the first five surveys taking place in the first month after the earthquake. Comparison of imagery from before and after the Mw 7.1 earthquake shows variation in slip on the main rupture and a small amount of distributed slip across the scene. Cracks can be observed and mapped in the high-resolution imagery, which show en echelon cracking, fault splays, and a northeast-striking conjugate fault at the Mw 7.1 rupture south of Highway 178 and near the dirt road. Initial postseismic results show little fault afterslip, but possible subsidence in the first 7–10 days after the earthquake, followed by uplift.

High-Resolution Structure-From-Motion Models and Orthophotos of the Southern Sections of the 2019 Mw 7.1 and 6.4 Ridgecrest Earthquakes Surface Ruptures

2020 ◽  
Vol 91 (4) ◽  
pp. 2124-2126 ◽  
Author(s):  
Ian Pierce ◽  
Alana Williams ◽  
Richard D. Koehler ◽  
Colin Chupik
Keyword(s):  
High Resolution ◽  
Structure From Motion ◽  
Point Cloud ◽  
Earthquake Sequence ◽  
Aerial Photographs ◽  
Motion Models ◽  
Cloud Models ◽  
High Resolution Structure ◽  
Surface Ruptures ◽  
Resolution Structure

Abstract Aerial photographs were collected in the days immediately following the 4–5 July 2019 Ridgecrest earthquake sequence (e.g., Barnhart et al., 2019) along the publically accessible sections of the surface ruptures south of California 178. These photos were then used to produce structure-from-motion point cloud models and orthophotos with resolutions varying from ∼1 to 20  cm/pixel. Here, the models are released and initial observations of the nature of the surface ruptures are presented.

scholarly journals High-Resolution Structure-from-Motion for Quantitative Measurement of Leading-Edge Roughness

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3916 ◽  
Author(s):  
Mikkel Schou Nielsen ◽  
Ivan Nikolov ◽  
Emil Krog Kruse ◽  
Jørgen Garnæs ◽  
Claus Brøndgaard Madsen
Keyword(s):  
High Resolution ◽  
Wind Turbine ◽  
Structure From Motion ◽  
Turbine Blades ◽  
Leading Edge ◽  
Cost Effective ◽  
Wind Turbine Blades ◽  
Edge Roughness ◽  
High Resolution Structure ◽  
Resolution Structure

Over time, erosion of the leading edge of wind turbine blades increases the leading-edge roughness (LER). This may reduce the aerodynamic performance of the blade and hence the annual energy production of the wind turbine. As early detection is key for cost-effective maintenance, inspection methods are needed to quantify the LER of the blade. The aim of this proof-of-principle study is to determine whether high-resolution Structure-from-Motion (SfM) has the sufficient resolution and accuracy for quantitative inspection of LER. SfM provides 3D reconstruction of an object geometry using overlapping images of the object acquired with an RGB camera. Using information of the camera positions and orientations, absolute scale of the reconstruction can be achieved. Combined with a UAV platform, SfM has the potential for remote blade inspections with a reduced downtime. The tip of a decommissioned blade with an artificially enhanced erosion was used for the measurements. For validation, replica molding was used to transfer areas-of-interest to the lab for reference measurements using confocal microscopy. The SfM reconstruction resulted in a spatial resolution of 1 mm as well as a sub-mm accuracy in both the RMS surface roughness and the size of topographic features. In conclusion, high-resolution SfM demonstrated a successful quantitative reconstruction of LER.

High-resolution observations of microscale influences on a tornado track using Unpiloted Aerial Systems (UAS)

2021 ◽  
Author(s):  
Melissa A. Wagner ◽  
Robert K. Doe ◽  
Chuyuan Wang ◽  
Erik Rasmussen ◽  
Michael C. Coniglio ◽  
...  
Keyword(s):  
High Resolution ◽  
Aspect Ratio ◽  
Past Research ◽  
Spatial Distance ◽  
Surface Model ◽  
Damage Site ◽  
Near Surface ◽  
Site Investigations ◽  
High Resolution Imagery ◽  
Aerial Systems

AbstractTopography can have a significant influence on tornado intensity and direction by altering the near-surface inflow. However, past research involving topographic influence on tornadoes has shown significant variety in investigative approaches and conclusions. This study uses Unpiloted Aerial Systems (UAS)-based high-resolution imagery, UAS-based 3D-modeling products, and correlation analyses to examine topographical influences on a portion of the 01 May 2018 Tescott, Kansas EF3 tornado. Two new metrics, Visible Difference Vegetative Index (VDVI) gap and (VDVI) aspect ratio, are introduced to quantify damage severity using UAS-based imagery and elevation information retrieved from a UAS-based digital surface model (DSM). Areas of enhanced scour are seen along the track in areas of local elevation maxima. Correlation analysis shows that damage severity, as measured by VDVI gap and VDVI aspect ratio, are both well correlated with increasing elevation. VDVI gap is only weakly correlated with slope, while VDVI aspect ratio is not correlated with slope. These findings are statistically significant at p < 0.05. As the tornado weakened in intensity, the path became non-linear, traversing between two local elevation maxima. It is hypothesized that fast-moving intense flow formed and weakened as elevation increased over the short spatial distance. This research shows topography and surface conditions are two of many important variables that should be considered when performing tornado-damage site investigations. It also illustrates the importance of UASs in detailed tornado analysis. VDVI gap and VDVI aspect ratio can provide insight into damage severity as a function of topography.

scholarly journals Effect of photogrammetric RPAS flight parameters on plani-altimetric accuracy of DTM

2020 ◽  
Vol 12 (1) ◽  
pp. 1017-1035
Author(s):  
Zuriel Dathan Mora-Felix ◽  
Antonio Jesus Sanhouse-Garcia ◽  
Yaneth A. Bustos-Terrones ◽  
Juan G. Loaiza ◽  
Sergio Alberto Monjardin-Armenta ◽  
...  
Keyword(s):  
High Resolution ◽  
Orthogonal Design ◽  
Low Cost ◽  
Image Data ◽  
Point Clouds ◽  
3D Models ◽  
Digital Terrain ◽  
High Resolution Imagery ◽  
Flight Parameters ◽  
Aerial Systems

AbstractRemotely piloted aerial systems (RPASs) are gaining fast and wide application around the world due to its relative low-cost advantage in the acquisition of high-resolution imagery. However, standardized protocols for the construction of cartographic products are needed. The aim of this paper is to optimize the generation of digital terrain models (DTMs) by using different RPAS flight parameters. An orthogonal design L18 was used to measure the effect of photogrammetric flight parameters on the DTM generated. The image data were acquired using a DJI Phantom 4 Pro drone and six flight parameters were evaluated: flight mode, altitude, flight speed, camera tilt, longitudinal overlap and transversal overlap. Fifty-one ground control points were established using a global positioning system. Multivision algorithms were used to obtain ultra-high resolution point clouds, orthophotos and 3D models from the photos acquired. Root mean square error was used to measure the geometric accuracy of DTMs generated. The effect of photogrammetric flight parameters was carried out by using analysis of variance statistical analysis. Altimetric and planimetric accuracies of 0.38 and 0.11 m were achieved, respectively. Based on these results, high-precision cartographic material was generated using low-cost technology.

Mapping and Monitoring of the Land Use/Cover Changes in the Wider Area of ltanos, Crete, Using Very High Resolution EO Imagery With Specific Interest in Archaeological Sites

2019 ◽  
Author(s):  
Sawyer Reid stippa ◽  
George Petropoulos ◽  
Leonidas Toulios ◽  
Prashant K. Srivastava
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Satellite Images ◽  
Archaeological Site ◽  
Digital Photography ◽  
Archaeological Sites ◽  
Large Area ◽  
High Resolution Imagery ◽  
Site Mapping ◽  
Rule Sets

Archaeological site mapping is important for both understanding the history as well as protecting them from excavation during the developmental activities. As archaeological sites generally spread over a large area, use of high spatial resolution remote sensing imagery is becoming increasingly applicable in the world. The main objective of this study was to map the land cover of the Itanos area of Crete and of its changes, with specific focus on the detection of the landscape’s archaeological features. Six satellite images were acquired from the Pleiades and WorldView-2 satellites over a period of 3 years. In addition, digital photography of two known archaeological sites was used for validation. An Object Based Image Analysis (OBIA) classification was subsequently developed using the five acquired satellite images. Two rule-sets were created, one using the standard four bands which both satellites have and another for the two WorldView-2 images their four extra bands included. Validation of the thematic maps produced from the classification scenarios confirmed a difference in accuracy amongst the five images. Comparing the results of a 4-band rule-set versus the 8-band showed a slight increase in classification accuracy using extra bands. The resultant classifications showed a good level of accuracy exceeding 70%. Yet, separating the archaeological sites from the open spaces with little or no vegetation proved challenging. This was mainly due to the high spectral similarity between rocks and the archaeological ruins. The satellite data spatial resolution allowed for the accuracy in defining larger archaeological sites, but still was a difficulty in distinguishing smaller areas of interest. The digital photography data provided a very good 3D representation for the archaeological sites, assisting as well in validating the satellite-derived classification maps. All in all, our study provided further evidence that use of high resolution imagery may allow for archaeological sites to be located, but only where they are of a suitable size archaeological features.

A high-resolution seismic catalog for the 2020 Magna, Utah, earthquake sequence

2020 ◽  
Author(s):  
Guanning Pang ◽  
Keith Koper ◽  
Maria Mesimeri ◽  
Kristine Pankow ◽  
Benjamin Baker ◽  
...  
Keyword(s):  
High Resolution ◽  
Earthquake Sequence ◽  
Seismic Catalog
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