Integration and Application of Multimodal Measurement Techniques: Relevance of Photogrammetry to Orthodontics.

Multimodal imaging, including 3D modalities, is increasingly being applied in orthodontics, both as a diagnostic tool and especially for the design of intraoral appliances, where geometric accuracy is very important. Laser scanners and other precision 3D-imaging devices are expensive and cumbersome, which limits their use in medical practice. Photogrammetry, using ordinary 2D photographs or video recordings to create 3D imagery, offers a cheaper and more convenient alternative, replacing the specialised equipment with handy consumer cameras. The present study addresses the question of to what extent, and under what conditions, this technique can be an adequate replacement for the 3D scanner. The accuracy of simple surface reconstruction and of model embedding achieved with photogrammetry was verified against that obtained with a triangulating laser scanner. To roughly evaluate the impact of image imperfections on photogrammetric reconstruction, the photographs for photogrammetry were taken under various lighting conditions and were used either raw or with a blur-simulating defocus. Video footage was also tested as another 2D-imaging modality feeding data into photogrammetry. The results show the significant potential of photogrammetric techniques.

Multimodal Imagery in Forensic Incident Scene Documentation.

Various imaging modalities are evaluated for use in forensic incident (crime or accident) scene documentation. Particular attention is paid to the precision vs. cost tradeoff, accomplished by judiciously combining various 3D scans and photogrammetric reconstructions from 2D photographs. Assumptions are proposed for two complementary software systems: an event scene pilot assisting the on-site staff in their work securing evidence and facilitating their communication with stationary support staff, and an evidence keeper, managing the voluminous and varied database of accumulated imagery, textual notes and physical evidence inventory.