Geophysical Survey

Our Equipment

GSSI Ground Penetrating Radar Utility Scan
Total Station with a Nikon camera, two prisms, poles, and a tripod
Emlid Reach RS and RS2
Bartington Grad601 Magnet Gradiometer (Magnetometer)
Polyga 3D Carbon Light Scanner
DJI Phantom 4 Drone

Ground Penetrating Radar

We use a GSSI UtilityScan GPR with 350 MHz frequency antenna and depth penetration up to 10 meters. The GPR is retrofitted with a Model 626 3-wheel cart for handling in grassy areas and uneven terrain. The unit is also equipped with a real-time kinematic GPS unit for simultaneous GPS and GPR collection.

Post-processing of data is completed in Radan-7 and ArchaeoFusion, an open source geophysical data processing software from the University of Arkansas.

Four main post-processing steps are conducted:

Time zero correction to adjust for surface reflection
Background removal to reduce horizontal background noise
Filtering to remove high and low-frequency noise
Migration to reduce hyperbolic reflection

Finished raster outputs are exported as time slices and geolocated in QGIS. Interpretations of anomalies digitized atop the rasters.

Example of anomalies suitable for the GPR:

Grave shafts
Building footprints
Earthworks
Utility pipes
Geologic features

Magnetic Gradiometer (Magnetometer)

We use a Bartington Grad601 magnetic gradiometer system with dual sensors. This mag system has selectable resolution of 0.01nT or 0.1nT, with exceptional temperature stability. The Grad601 also automatically adjusts to reduce power line noise with its 50/60 Hz rejection.

Data is downloaded to TerraSurveyor for data cleaning as necessary to improve data interpretability (such as spike removal, denoising, and de-striping) and grid combination. The data is then exported in a raster format to QGIS for geolocation and interpretation.

Examples of anomalies suitable for the magnetometer:

Grave shafts
Building footprints
Disturbed earth
Fire footprints
Unexploded ordinance detection
Pipe, cable, and drum locations

Total Station & Emlids

The Total Station and Emlids are used to provide exact locations for marking points of interest, boundaries, and more in a land survey. They use satellite connections to understand their location and feature a base station and rover, allowing for ease of movement in collecting points.

Structured Light Scanning

Our Polyga structured light scanner captures submillimeter 3D renderings of objects using various light technologies to represent textures, colors, and subtle contours of objects from the size of coins to human scale, and even partial room-size surfaces. We have extensive experience scanning artifacts for museum and archaeological project collections, enabling researchers and the public to interact with objects virtually.

VH_L451 Fire Department Button by SARL on Sketchfab

Drone Survey

Mawchu Llacta, central area by SARL on Sketchfab

We offer drone-based aerial photogrammetry with advanced processing capabilities for detailed 3D and 2D documentation at site- and landscape-scales.

Project Deliverables

Each project produces a detailed report of finding, featuring background information on the site including historical context and historical maps when accessible, information on the scope and methods of the project, a detailed table of the grid extents, maps of the survey grids and their prospective GPR or magnetometer results, interpretations of the data, and recommendations for further action. We attribute sources utilized and collaborate with local historians and experts to interpret our data.