https://cdn.specpick.com/images/photonics/sanandresfault_wall.jpg712370
The Department of Geological Sciences at San Diego State Univ. (SDSU) has teamed up with Geodetics Inc, a leading manufacturer of integrated mobile mapping systems, to research the San Andreas Fault in southern California. The study scanned the fault with Geodetics’ drone-based Geo-MMS LiDAR/Camera mapping system that uses Velodyne LiDAR technology and an RGB camera to deliver the most accurate 3D data on the market.
Scientific study of the evolution of the southern end of the San Andreas Fault is of vital importance given the earthquake-prone nature of southern California. Mapping fault zones and land surface changes that resulted from previous earthquakes can deepen the understanding of hazards posed by the fault, including the possibility of future temblors. The research is thus focusing on evaluating both past large slip events (earthquakes) and aseismic creep (also known as “silent earthquakes”), which are tremors that release their energy over weeks or months rather than seconds. It is looking to discover new fault zones and active fault traces, which are visible marks where a geological fault meets the ground surface. The research is also looking to detect fault slip that has resulted from past earthquakes.
LiDAR mapping represents a very exciting technology for geology since it enables the generation of accurate 3D mapping, even in the vertical component where classical photo-grammetry techniques are lacking. Researchers at SDSU are planning to continuously monitor the fault to better characterize it and exploit the advantages of the current 3D mapping technique.
San Andreas Fault Research
In their study, SDSU researchers are developing a comparison between several techniques for evaluating past slip events and looking to establish precision and accuracy of the techniques relative to each other.
Previous work in this area has utilized traditional photo-grammetry techniques using small drones to build digital terrain models of earthquake faults. The Structure from Motion (SfM) approach in photo-grammetry to monitor topography changes has been a hot topic in geology for the past two years. However, SfM does not have inherent referencing scale – the scale at which symbols and labels appear on a map at their intended, true size.
Other techniques involve LiDAR with the U.S. Geological Service using airborne LiDAR while other researchers have tapped ground-based LiDAR to map topographic expression of the fault and examine offsets, which are the distance the fault is out of line with the map.
The SDSU team used a Geodetics Geo-MMS system including the mapping payload and DJI Matrice M600 Pro drone for its San Andreas Fault mapping. The Geo-MMS payload was equipped with Geodetics’ Point&Pixel Technology (the Point (provided by the LiDAR) and Pixel (provided by the camera)) which enabled researchers to generate 3D models without the use of ground control points (GCP), which are marked points on the ground that have known geographic locations.
Geo-MMS, which currently uses several Velodyne LiDAR sensors including the Velodyne PUCK VLP-16 sensor, delivers accurate geo-referenced LiDAR point clouds to customers in agriculture, construction, forestry, infrastructure, mining and urban planning. Since Geodetics develops all electrical, mechanical, algorithm design and software components used in its products, the company is in a unique position in the LiDAR drone mapping space to innovate quickly to deliver new state-of-the-art technologies.
Geodetics is deepening its relationship with Velodyne by expanding its Geo-MMS product offering with integration with the Velodyne's ULTRA Puck VLP-32C. The VLP-32C is a long-range LiDAR sensor that combines best-in-class performance with a small form factor. It is a high-resolution LiDAR sensor that is cost effective compared to similar performance sensors and retains innovative breakthroughs such as 360° surround view along with real-time 3D data that includes distance and calibrated reflectivity measurements along with rotational angles.
Geodetics is also introducing the innovative Point&Pixel capability to its Geo-MMS product offerings, advancing its strategy to provide industry professionals with cost-effective, streamlined solutions to produce 3D geo-referenced point clouds. Point&Pixel enables accurate colorization of the LiDAR point cloud using synchronously captured RGB images from a camera during the same flight as the LiDAR scanning collection. The industry-leading Geodetics approach allows users to create colorized point clouds and photomosaic quickly without requiring multiple over-flights of an area or different scan patterns. Point&Pixel is expected to be available in the third quarter of 2018.
Additionally, Geodetics is introducing its new Geo-Photomap product for applications such as vertical mapping and corridor mapping. Geo-Photomap enables accurate automated 3D mapping using direct-geo-referenced images (geo-tagged images) – images associated with a geographic location. With Geo-Photomap, high-accuracy positioning and external orientation angles are generated, eliminating the need for ground control points and reducing image overlap to as low as 30 percent resulting in significant cost savings.
