Orbital and sub-orbital multi-spectral remote sensing has been successfully used for lithologic mapping in geological studies for over forty years now. In this study, multi-spectral imaging is used to remotely sense lithological units at the outcrop scale using the turbidites of the Jackfork Pennsylvanian at Big Rock Quarry, Arkansas as a test site. Remote sensing techniques are integrated with 3D digital mapping techniques to create a 3D photorealistic multi-spectral model of the outcrop.

Analyses of the spectral features of the different turbiditic rock types within the visible and near infrared (VNIR) portion of the electromagnetic spectrum can effectively help in the identification of the lithology when the difference is not obvious on the outcrop. Multi-spectral images are acquired using a digital camera with appropriate lens filters that allow only portions of the electromagnetic spectrum with specific wavelengths (bands) to be recorded. The wavelengths of these filters are selected to coincide with wavelengths where diagnostic spectral features are present in the spectral curves of different rock types. Individual bands are co-registered and displayed in Red-Green-Blue (RGB) color space to create false color images that are useful for highlighting lithologic variation of the outcrop. False-color images are farther draped onto three-dimensional digital model of the outcrop extracted from terrain data that were collected using an integrating system of a RTK-GPS and a high-density laser scanner. Remote sensing and digital model co-registration and draping process takes place at a few centimeter accuracy and resolution.

The integration of remote sensing data and 3-D digital model of the outcrop allowed us to capture the three dimensional spatial distribution of lithological units, which is fundamentally important for understanding the internal architecture of erosional and depositional features, in this case channelized features.