iWitness摄影测量系统在颌面部应用的可信度研究

目的 通过对头部模型面部的测量分析，来研究iWitness摄影测量系统在颌面部应用的精确性与准确性。方法 利用iWitness摄影测量系统重复获取头部模型标志点的三维坐标值，来评估在不同状态下系统应用的精确性。通过计算模型三维测量的线性距离值与真实距离值之间的差异及分布情况来检查测量数据的准确性与偏倚性。结果 在非缩放状态与缩放状态下操作误差分别为0.20 mm和0.09 mm，两者间差异有统计学意义（P<0.05）；摄像误差为0.283 mm，与同一组图像的测量结果相比较，差异无统计学意义（P>0.05）；经多次校正的误差为0.251 mm，与仅作一次校正的摄像误差比较，差异无统计学意义（P>0.05）。距离测量差异集中于±0.4 mm之间，准确性较高，无偏倚。结论iWitness摄影测量系统在颌面部的标志点定位与点距测量上具有较高的可信度，可应用于面部形态的评估与记录。

Reliability of iWitness photogrammetry in maxillofacial application

Objective This study aims to test the accuracy and precision of iWitness photogrammetry for measuring the facial tissues of mannequin head. Methods Under ideal circumstances, the 3D landmark coordinates were repeatedly obtained from a mannequin head using iWitness photogrammetric system with different parameters, to examine the precision of this system. The differences between the 3D data and their true distance values of mannequin head were computed. Results Operator error of 3D system in non-zoom and zoom status were 0.20 mm and 0.09 mm, and the difference was significant (P<0.05). Image captured error of 3D system was 0.283 mm, and there was no significant difference compared with the same group of images (P>0.05). Error of 3D system with recalibration was 0.251 mm, and the difference was not statistically significant compared with image captured error (P>0.05). Good congruence was observed between means derived from the 3D photos and direct anthropometry, with difference ranging from −0.4 mm to +0.4 mm. Conclusion This study provides further evidence of the high reliability of iWitness photogrammetry for several craniofacial measurements, including landmarks and interlandmark distances. The evaluated system can be recommended for the evaluation and documentation of the facial surface.