THE USE OF OBLIQUE CLOSE-RANGE MULTI-SPECTRAL IMAGERY IN DIGITAL 3-D MAPPING OF THE JACKFORK TURBIDITES AT BIG ROCK QUARRY, ARKANSAS

Remote sensing analyses for lithologic mapping is common from airborne and space platforms, but in this study it is applied to digital photography acquired obliquely from the ground, to test the possibility of automatic, digital detailed outcrop mapping of lithologies. Multi-spectral imaging is applied to map the detail lithology of Jackfork Formation at outcrop scale using the turbidite at Big Rock Quarry, Arkansas as a test site. Remote sensing techniques operating in the near infrared through the thermal infrared are integrated with unique 3-D photorealistic digital mapping in the visible part of the spectrum, creating a series of co-registered 3-D multi-spectral models of the outcrop. Laboratory analysis of the absorption characteristics indicates that middle infrared spectra can provide sand/shale discrimination, but no such cameras sensitive to that part of the spectrum have been available, until recently. We are now testing such handheld digital cameras sensitive to the middle IR part of the spectra, combining their imagery with visible-near infrared imagery of another type digital camera and texture mapping them onto 3-D models from laser scanning, with appropriate lens band pass filters. 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 variations of the outcrop. False-color images are farther texture mapped onto the three-dimensional digital model of the outcrop built from terrain data collected using a combination of RTK-GPS, and laser scanners.