Seminar Series - Fall 2009

Outcrops are valuable sources of three-dimensional geologic information, but are often inaccessible or short-lived. Terrestrial photography, photogrammetry, and remote sensing can be used to collect outcrop information, including elevations and locations tied to real-world coordinates.

Control and check points are established using identifiable marks or recesses in the surface, distinct rock coloration, and prominent bends and intersections of joints. Camera stations and ground control points on an outcrop or highwall are surveyed using GNSS and reflectorless total station technology. Stereophotography is processed by photogrammetric software to make a 3-D stereomodel to remove radial displacement and error to make an orthorectified digital image from which georeferenced measurements can be made.

Georeferenced bedding contacts; measurements of dip and strike; lengths of surfaces; and the orientation and spacing of joint planes, beds, and identifiable surfaces can be compared between physically separated outcrops. Studies at a dolomite quarry in Chicago found that individual beds were not laterally continuous as had been perceived by the unaided eye. Joints are not as frequent, well developed, nor vertically continuous as expected.

Imagery of glacial sediments at a silica mine near Wedron were enhanced to differentiate oxidized and unoxidized sediments. Image processing techniques were used to distinguish sand, diamicton and lake sediments.

Future research is planned to determine how multichannel imagery of outcrops, including that in the nonvisible wavelengths, can be used for lithologic descriptions, moisture content, sedimentary structure, and perhaps texture associated with mineral suites. We also plan to test whether these tools can improve sampling priorities by eliminating human bias in the field. Technical challenges to using these tools and techniques include illumination, acquisition, outcrop moisture, and incorporating this information into 3-D models for analysis and visualization.

Other Seminars and Colloquia of interest on the UIUC Campus

Department of Geology

Department of Geography (check under Activities)

Department of Natural Resources and Environmental Science

Updated 11/13/2009 SLD