JULY 9, 2009--Acquiring 3-D information for the geometric modeling of objects up to 100 m is essential for applications like industrial site reconstruction, cultural heritage monitoring, or city modeling. The accuracy requirement is between +/-0.5 mm and +/-2 cm, depending on the application. To meet these application demands, two measurement devices used in such applications--laser scanners and range cameras--require improved accuracy.
While laser scanners and range sensors such as time-of-flight cameras measure angles and ranges, the results are often processed as 3-D point clouds. The resulting range calibration methodologies have great potential for error.
Using new range calibration methodologies, researchers Norbert Pfeifer, Camillo Ressl, and Wilfried Karel at the Institute of Photogrammetry and Remote Sensing, Vienna University of Technology (Vienna, Austria; www.ipf.tuwien.ac.at) have reduced the systematic errors in laser scanning point clouds by more than 50% and improved overall accuracy.
Although they can reduce systematic errors for range imaging cameras, residual systematic errors remain considerable. Ideally, technological advances in range cameras will increase precision and resolution, but for now a solution is still required for the calibration task.
The researchers are continuing to investigate the integration of other sensors for observing elements of the outer orientation (the angular attitude of the device) as a possible solution.
For more info, visit http://spie.org/x36011.xml?ArticleID=x36011.
-- Posted by Conard Holton, Vision Systems Design, www.vision-systems.com