Displacement is the cornerstone of almost all of 3vG’s business; as such, most of our products are intended to assess stability, communicate movement, and provide displacement histories. Our ongoing monitoring program is designed to provide clients with actionable intelligence that allows them to mitigate risk. 3vG’s InSAR services programs monitor our clients’ vital assets such as tailings dams, pipeline right of ways, and bridges, as well as critical slopes for creep and landslide detection.
One of 3vG’s flagship products is the Rapid Report. These near real-time displacement reports typically service clients who need immediate alerts to new and/or accelerating geohazards. InSAR analyses are based on comparing the latest satellite image acquisition with other recently acquired images. Results are generally displayed as spatial data (color-coded contours) that indicate the magnitude, location, and extent of all identified motion areas. Most importantly, they are delivered within 24 hours of 3vG receiving each new satellite image. Since many of our clients operate 365 days a year, so do we. Rapid Reports can also be used for non-displacement data, such as coherence analyses or waterbody monitoring.
Sample Rapid Report
Comprehensive Reports are based on InSAR analyses of the complete set of SAR images available over a defined area of interest (AOI). This approach, combined with advanced processing techniques, generates tens of millions of data points across the AOI, each with long-term measurements of displacement over time. Precise measurements of subtle displacement are possible, including the total cumulative displacement over the time period analyzed. Potential regressive and progressive (i.e., non-linear) displacement trends are visible.
3vG typically delivers InSAR displacement results through ArcGIS, QGIS and/or Google Earth. 3vG can also support integration of our data into programs such as MapInfo, AutoCAD, MAPTEK, Navstar/GeoExplorer. We have developed a custom toolbar for GIS software platforms to assist clients in efficiently visualizing displacement information and conducting additional analyses and statistics. The current version includes site selection, time range, point selection tools, export data options, report statistics and graph displacement options.
Typically, a minimum of 15 usable SAR images are required in order to conduct comprehensive InSAR analyses. In addition to the displacement files, 3vG delivers a written PDF report that summarizes an overview of the AOI, the radar satellite data used, a summary of our processing methodology, and select displacement measurements for specific areas of interest. These measurements are shown as color-scaled targets overlaying an optical satellite image of the locations. Time series displacement curves are provided for select data points of interest.
Sample Comprehensive Report
3vG can conduct a quick, low-cost coherence analysis based on just 3 satellite images to evaluate the expected data coverage and output quality of a full InSAR analysis. These coherence checks incorporate both geometric effects (i.e., layover and shadow created by the satellite’s line of sight relative to the topography), as well as the impact of ground cover on the radar signal (e.g., vegetation, agriculture, etc.) Using the results of the coherence analysis, 3vG works with clients to determine the best path forward for long-term image acquisitions and InSAR analyses.
The image above is of a river valley with steep and varied topography and partially vegetated slopes. The satellite was traveling in the Ascending (north) direction, with the radar signal’s line of sight projected to the east. The coherence analysis helped inform our client as to where we expect to be able to generate displacement measurements (white and grey-scale areas) and where we won’t have data coverage (black areas), relative to some specific and critical areas of interest.