CAPTURE AND CONSTRUCTION OF PHOTOREALISTIC 3D GEOLOGIC MODELS OF THE PENNSYLVANIAN HARTSHORNE SANDSTONE OF HUCKLEBERRY CREEK SPILLWAY IN CENTRAL ARKANSAS

The Huckleberry Creek Spillway is part of the Hartshorne Sandstone sequence of Pennsylvanian age. It is a well-visited area by undergraduate and graduate students in sedimentology and stratigraphy, as well as industry leaders. The spillway exposes both northern and southern cuts of the sequence and gives a clear view of the three-dimensional aspects of the geology in the area. In the spring of 2007, a group of undergraduate students, who planned, researched, and organized the project, digitally captured a portion of these two outcrops. The data was gathered with the use of a Riegl LPM 800 terrestrial laser scanner, RTK GPS equipment, and a digital camera. High-resolution photos were taken in concordance with the scanned data for later photo draping over the 3D models. With the terrain and single day time constraint taken into account, the laser scanner was positioned for maximum coverage, with a total of four scan positions; resulting in eight scanned images composed of massive point clouds of data. In order to construct an accurate 3D model from the point clouds, reflectors were placed along the top and bottom of the exposure to assist alignment of the images in post processing. In addition, control reflectors were placed, and positioned by RTK GPS and tied to a nearby Continuously Operating Reference Station in order to globally position the data. This process, along with the use of software created at the University of Texas at Dallas, as well as commercial software, allowed students to construct a spatial 3D model and accurately recreate the geology of the spillway.