Structure-from-Motion is now a standard technique for documenting outcrops and paleoseismic trenches. It is also widely used in archaeology, architecture, disaster response, etc. In a perfect world, we would always have lots of well-known ground control points (GCPs) for our 3D models, for example by using a differential GPS. However, quite often we can’t do that because we don’t have a dGPS, because we stumbled upon an outcrop by accident, because we don’t want to carry the tripod to the top of a summit, etc. The problem is that without GCPs we might end up with funny errors in our model. Ian Pierce has written a tutorial about how to overcome many of these problems by combining SfM with the scans of the iPad’s and iPhone’s built-in lidar sensor: https://neotectonic.github.io/posts/iOS_Surveying/
This is the April edition of my paper round-up. Today I recommend papers on high-resolution topography data, fault mechanics, earthquake environmental/archaeological effects (liquefaction, rotated objects, landslides), Quaternary dating, a fault database for Asia, and tectonics of New Zealand and Martinique. Enjoy! more
A few weeks ago, Nadine Reitman (USGS) published an interesting paper about the use of Photogrammetry for Paleoseismic Trenching in BSSA. In this guest blog she shares her key findings and explains how to minimise errors without spending too much time measuring control points. Thanks Nadine!
Structure-from-motion (SfM) is now routinely used to construct orthophotos and high-resolution, 3D topographic models of geologic field sites. Here, we turn SfM on its side and use it to construct photomosaics and 3D models of paleoseismic trench exposures. Our results include a workflow for the semi-automated creation of seamless, high resolution photomosaics designed for rapid implementation in a field setting and a new error analysis of SfM models. more
I’ve spent several weeks in Eastern Kazakhstan this summer for paleoseismological field work. During the first part of this trip we looked at some thrust and strike-slip faults in the Ili Basin and the Saty area. The second part was almost entirely devoted to study the Dzhungarian Fault. I’ll blog about this second part later. Eleanor, David, Austin and me were the UK representatives in our team. We were so lucky to have Kanatbek from Kyrgyzstan and Aydin from Kazakhstan with us. They did not only lead us to all the interesting places and helped us to understand the geology and the tectonics, but they also did a fanatastic job organizing the field trip and dealing with the local surprises, which as you know happen in basically every field trip.
Our first study site was located at the northern boundary of the Ili Basin, where we did some work last year already. more
Last Friday the RAS held a discussion meeting on Tectonics from Above: Recent Advances in the Use of High-resolution Topography and Imagery in London. Almost the entire Cambridge Tectonics Group went there and I absolutely enjoyed the meeting and the discussion with friends and colleagues mainly from the UK and from France. The speakers reported on open-source software for producing high-res DEMs, advances in aerial and satellite imagery, new techniques in remote sensing, and latest developments in fault/offset mapping. The meeting was supported by NERC, COMET+ and LICS. more