170 Geology and Health (Posters)

Tuesday, 11 October 2011
9:00 AM - 6:00 PM
Hall C

COMBINING A ROBOTIC CAMERA SYSTEM WITH TERRESTRIAL LIDAR TO PRODUCE VERY HIGH RESOLUTION PHOTOREALISTIC OUTCROP MODELS

Paper number: 170-11
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

A major impediment to the creation of very high resolution photorealistic models is the need to accurately and efficiently align the photographs to the model. Early model creation used handheld cameras and manually selected tiepoints that related the photograph to the TIN mesh model derived from the point cloud. Selection of the tiepoints could require hours per photo and in many cases accurate alignment failed. Mounting the camera onto the scanner allows the photograph alignment to the model to be determined by the scanner software. However, increasing the focal length of the lens to achieve high resolution is limited by the need to have a focal length which adequately covers the scan swath. To overcome these problems, a camera-mounted robotic pan-tilt system has been combined with a robotic total station to provide high accuracy tiepoints between the photographs and the outcrop model without restricting the lens that is used on the camera.

GeoConstructor is a suite of software applications that control the actions of a Topcon IS robotic total station and a Nikon camera mounted on a Directed Perception pan-tilt robot. The total station surveys the reflector controls and the area to be photographed is delineated. Shot patterns for the total station and for the camera are defined and the total station takes a through-the-telescope photo of the crosshair location for each tiepoint measurement. The camera/pan-tilt system is aligned to the reflector controls and the required photographs are taken. The total station photos are aligned to the camera photographs using image matching, accurately placing the tiepoint measurements in the camera photographs.

Two large, high resolution photorealistic models of outcrops were acquired and processed in 2010 by UTD under contract to Saudi Aramco. One model covers over 4 km of outcrop and the other covers in excess of 2.5 km of outcrop with some features reaching 80 m in height. Each model contains over eight hundred 24.5 megapixel photographs using images acquired with a Nikon D3X and lenses of 105 mm and 300 mm. The rms residuals for alignment of the photos to the models are typically 1 pixel. The 300 mm lens provides images with resolutions between 1 and 1.5 mm per pixel.