Magnetometry¶

Magnetometry measures spatial variations in Earth's magnetic field to reveal the distribution of magnetic minerals in the subsurface. These variations help identify geological structures, lithological boundaries, and zones of hydrothermal alteration associated with mineralization.

In TerraEye, magnetometry layers are derived from the EMAG2 v3 global magnetic anomaly grid — a compilation of satellite, airborne, and marine survey data at 2 arc-minute resolution. For North America and Australia, higher-resolution regional models are also available.

How to Use the Magnetometry Layer?¶

Go to the Data tab, expand Magnetometry, and click Add layer.
Select a magnetic product from the dropdown:
- TMI — Total Magnetic Intensity; raw magnetic field values in nanoteslas [nT].
- TMI AS — Analytic Signal; highlights edges of magnetic bodies regardless of field inclination.
- TMI RTP — Reduction to Pole; places anomalies directly above their geological sources.
- TMI RTP 1VD — First Vertical Derivative; enhances shallow structures and acts as an edge detector.
- TMI RTP 2VD — Second Vertical Derivative; higher resolution than 1VD, more sensitive to shallow features.
- TMI RTP HG — Horizontal Gradient; maps contacts and edges of magnetic sources.
- TMI RTP Residual — highlights local anomalies by removing the regional magnetic trend.
- TMI RTP Tilt — Tilt Derivative; zero crossings delineate edges of magnetic sources.
Switch between Raster and Shaded display mode.
In Shaded mode, adjust Light Controls to enhance relief:
- Azimuth — direction of the light source [0–360°]
- Altitude — elevation angle of the light source [1–90°]
- Z-Factor — vertical exaggeration [0.1–100]
Select a Shading model:
- Standard Lambertian — uniform illumination model.
- Aspect-Adaptive — adjusts illumination based on surface orientation for better feature visibility.
Toggle Clip Out-of-Range to hide values outside the selected range, or Show Contours to display contour lines.
Adjust Opacity to blend the layer with the base map.