Recent Advances in Range Imaging Metrology
Event details
| Date | 27.05.2011 |
| Hour | 11:00 |
| Speaker | Prof. Derek Lichti, Department of Geomatics Engineering, The University of Calgary, Canada |
| Location |
GC C2 413
|
| Category | Conferences - Seminars |
Time-of-flight range cameras using photonic mixer device technology offer great potential for close range metrology as there are many perceived advantages over other optical imaging methods such as photogrammetry and laser scanning. Unlike passive-image photogrammetry, a range camera can capture 3D data from a single sensor so there is no correspondence problem to solve and targeting is not required. Unlike a laser scanner that captures 3D point measurements in a sequential manner, a range camera features simultaneous 3D data capture of all points within its field view. In addition, the cost of a range camera is much lower than that of a laser scanner. The drawbacks of a range camera for metrology include low sensor resolution, low ranging accuracy and the data are contaminated by many errors that include both random sources (e.g. shot noise) and systematic sources. The latter can be categorised as either scene-dependent errors (e.g. the internal scattering artefact) or scene-independent, instrumental errors (e.g. lens distortion, periodic errors). Solutions to these problems that allow the use of a range camera for precise structural deformation measurements with millimetre-level accuracy will be described in this three-part presentation. First, experiments to characterise the internal scattering artefact and proposed correction models will be presented. Second, the scene-independent errors models will be reviewed and a performance comparison of three self-calibration techniques for the model coefficient estimation will be presented and analysed. Finally, the application of range cameras to structural deformation measurement will be described. Laboratory testing of reinforced concrete beams has been performed to quantify the efficacy of reinforcement with steel-reinforced polymer sheets. Techniques to reduce the impact of both the scene-dependent and the random errors on deflection measurements made with a range camera will be detailed. Results obtained with a SwissRanger SR4000 range camera will be presented and compared with those from a terrestrial laser scanner for accuracy assessment.
Practical information
- General public
- Free
Contact
- V. Boillat Kireev, tél. 021/ 693 2755 (int. 3 2755)