Oblique Helicopter-Mounted Lidar Combined with Multiresolution Modelling for the Creation of High Resolution, Wide-Area Virtual Geological Outcrops

Simon J. Buckley¹, John A. Howell¹, Julien Vallet², Walter Wheeler¹, and Alvar Braathen^3
1Centre for Integrated Petroleum Research, University of Bergen, Bergen, Norway
²Helimap System, CH-1066 Epalinges, Switzerland
³University Centre on Svalbard, Longyearbyen, Norway

In recent years terrestrial laser scanning (lidar) has become an effective method for the capture of 3D outcrop data, because of the high resolution and accuracy. However, current methods are limited by accessibility and scanner range. Many larger outcrops are unsuitable for ground based lidar, as it is not possible to get far enough away from the outcrop base and stay within the maximum scanner range. In this research, a laser scanner and digital camera were mounted onto a helicopter. This allowed the scanner to be positioned both closer and at a more optimal angle to the outcrop face. The system is based on conventional approach found with other aerial systems, but is side- rather than nadir-looking.

The method was tested on large carbonate outcrops from Billefjorden on Spitsbergen. The outcrops contain laterally extensive paleo-karst surfaces with dissolution along joints and faults filled with columnar breccia bodies. With heights of over 800m, tens of kilometres lateral extent, and near-vertical cliffs, these outcrops would have been impossible to capture using ground-based lidar.

Use of an aerial platform to capture large areas creates further challenges in the processing workflow. Tens of millions of points and hundreds of images were collected in just a few hours of flying time. This has significant implications for storage, processing and the ability to view the resultant virtual outcrops in real-time. New methods for creating multiresolution segmentation of the dataset are presented that allow very large virtual models to be interactively visualized and interpreted.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas