BGC is an industry leader in using remote sensing technologies to observe, interpret, and understand the physical environment, particularly as it applies to mapping differential change. Monitoring of slope movement has traditionally been limited to costly sporadic borehole mapping and instrumentation data, discrete surface measurements and observations, and interpolated geophysical data. However, recent advancements in remote sensing (LiDAR and Photogrammetry) data collection and analysis algorithms have enabled slope processes to be mapped, and thereby understood, with a greater degree of accuracy and confidence than was previously possible. BGC has extensive experience working with airborne laser scanning, terrestrial laser scanning, satellite InSAR, terrestrial radar, and photogrammetry for mapping differential slope change. We utilize our expertise to provide our clients with a better understanding of the rate of movement of material in the vicinity of their assets and to create an assessment of the associated potential hazards.
LiDAR is a surveying technology that measures distance by illuminating a target with a laser light, and is typically used to make high-resolution maps. Airborne Laser Scanning (also airborne LiDAR) is when a laser scanner, while attached to a plane or helicopter during flight, creates a 3D model of the landscape. ALS technology enables the collection of data over spatially extensive regions while requiring limited ground access to sites, and is currently the most detailed and accurate method of creating digital elevation models.
Terrestrial Laser Scanning (also terrestrial LiDAR) data collection requires ground access to scan setup locations, but does not require on-site access to the terrain being scanned. The TLS data can be used to identify small-scale features not typically possible in ALS data, and can create realistic looking 3D models in a relatively short time when compared to other technologies. TLS equipment can be rapidly deployed and the data integrated into differential models within hours of collection.
Photogrammetry is the science of making measurements from photographs. In essence, the distance between two points can be determined by measuring their distance on a photo image, so photogrammetry may be used to determine the exact position of surface points as well as the motion pathways of reference points located on a moving object. In this way, photogrammetry can provide excellent 3D models for various engineering geology applications. BGC has pioneered methodologies for helicopter based photogrammetry data collection and differential change of rock slopes along transportation corridors.
Radar interferometry methods are used to measure changes and displacements of natural and man-made slopes. Satellite methods provide data for large areas at regular intervals. Terrestrial methods can provide near-real time measurements of slopes of concern. BGC are experts in the analysis and interpretation of data from the industry leading satellite data providers and commonly used terrestrial hardware systems.
Remote sensing tools can provide powerful data sets for change detection mapping. But determining which tool, or combination of tools, provides the best solution for a particular project requires in-depth knowledge. For example, photogrammetric analysis may be applied to one photograph, or may be combined with ALS or TLS to detect, measure and record complex 2-D and 3-D motion fields.
BGC assists our clients to determine the best remote sensing technology for their application. Our experts have the experience necessary to support our clients to make good technology decisions, and we use state of the art analytical techniques to ensure they get accurate results. In addition, we continue to advance the field of change detection mapping as we have published, and are producing, leading papers in the industry. BGC has worked on advanced change detection projects in North and South America, Europe, and Australia.