|
| ||
|
|
||
Accurate Registration (accurate + registration)
Selected AbstractsScan registration for autonomous mining vehicles using 3D-NDTJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2007Martin Magnusson Scan registration is an essential subtask when building maps based on range finder data from mobile robots. The problem is to deduce how the robot has moved between consecutive scans, based on the shape of overlapping portions of the scans. This paper presents a new algorithm for registration of 3D data. The algorithm is a generalization and improvement of the normal distributions transform (NDT) for 2D data developed by Biber and Strasser, which allows for accurate registration using a memory-efficient representation of the scan surface. A detailed quantitative and qualitative comparison of the new algorithm with the 3D version of the popular ICP (iterative closest point) algorithm is presented. Results with actual mine data, some of which were collected with a new prototype 3D laser scanner, show that the presented algorithm is faster and slightly more reliable than the standard ICP algorithm for 3D registration, while using a more memory-efficient scan surface representation. © 2007 Wiley Periodicals, Inc. [source] Effect of lateral target motion on image registration accuracy in CT-guided helical tomotherapy: A phantom studyJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 3 2010J Medwig Summary Optimisation of imaging modes for kilovoltage CT (kVCT) used for treatment planning and megavoltage CT (MVCT) image guidance used in ungated helical tomotherapy was investigated for laterally moving targets. Computed tomography images of the QUASARÔ Respiratory Motion Phantom were acquired without target motion and for lateral motion of the target, with 2-cm peak-to-peak amplitude and a period of 4 s. Reference kVCT images were obtained using a 16-slice CT scanner in standard fast helical CT mode, untagged average CT mode and various post-processed 4D-CT modes (0% phase, average and maximum intensity projection). Three sets of MVCT images with different inter-slice spacings of were obtained on a Hi-Art tomotherapy system with the phantom displaced by a known offset position. Eight radiation therapists performed co-registration of MVCT obtained with 2-, 4- and 6-mm slice spacing and kVCT studies independently for all 15 CT imaging combinations. In the investigated case, the untagged average kVCT and 4-mm slice spacing for the MVCT yielded more accurate registration in the transverse plane. The average residual uncertainty of this combination of imaging procedures was 0.61 ± 0.16 mm in the longitudinal direction, 0.45 ± 0.14 mm in the anterior,posterior direction and insignificant in the lateral direction. Manual registration of MVCT,kVCT study pairs is necessary to account for a target in significant lateral motion with respect to bony structures. [source] Stabilized Record Base for Implant TreatmentJOURNAL OF PROSTHODONTICS, Issue 7 2010Susan S. Nimmo DDS Abstract It is important to obtain an accurate interocclusal record for the restoration of patients undergoing implant treatment. Atrophic alveolar bone in the mandible not only limits the placement of implants, but also contributes to deficient ridge morphology resulting in unstable record bases. Securing the record base to the implants is a useful way to obtain an accurate registration. The technique presented in this article uses two widely spaced implants as the optimal number of implants to stabilize record bases. [source] Orthodontics Using an Occlusal Splint: A Clinical ReportJOURNAL OF PROSTHODONTICS, Issue 2 2010Akit Patel BDS, MClinDent (Prostho), MFDS RCS (Eng) Abstract Careful management of the occlusion is necessary for successful prosthodontic treatment. A reorganized occlusal approach requires a more accurate registration of the desired jaw position, and where it is difficult to achieve this, an occlusal splint is indicated. This clinical report documents a 60-year-old man with a Prosthodontic Diagnostic Index Class IV dentition, who prior to a full-mouth reconstruction, underwent occlusal splint therapy with a Michigan-type splint that incorporated z-springs to allow concurrent orthodontic tooth movement of two anterior teeth to positions that would allow favorable restorations by correcting occlusal and esthetic form. [source] | ||||||||||