No abstract

Measurements made on models scanned by the 3D structured-light scanner were in good agreement with those made on conventional plaster models and were, therefore, clinically acceptable.

Objective: Fast and non-invasive systems of the three-dimensional (3D) technology are a recent trend in orthodontics. The reproducibility of facial landmarks is important so that 3D facial measurements are accurate and may be applied clinically. The aim of this study is to evaluate the reproducibility of facial soft tissue landmarks using a non-invasive stereo-photogrammetry 3D camera. Material and methods: Twenty-four soft tissue landmarks on 3D facial images captured using a VECTRA-3D dual module camera system for full face imaging (Canfield Scientific Inc, Fairfield, NJ, USA) were viewed and analysed using Mirror software on 30 adult subjects (15 males and 15 females, in the age range of 20–25 years). The landmarks were identified, recorded and measured twice on each 3D facial image by one examiner after a 2-week interval. Intra-class correlations and paired t-test or Wilcoxon Rank test were performed for each landmark to assess intra-examiner reproducibility. Results: Intra-class correlation coefficients for all 24 landmarks ranged from 0.68 to 0.97, indicating moderate to high reliability and reproducibility of all facial soft tissue landmarks. Paired t-tests and Wilcoxon Rank test also revealed that there were no significant differences in all 24 facial soft tissue landmarks measurements (p = 0.17 – 0.99). Conclusion: The results indicated that the reproducibility of identification of landmarks by one operator on facial images captured using a VECTRA-3D camera was acceptable. This device may be useful in treatment planning and may provide accurate information in making clinical decisions. However, it is suggested that further studies on inter-examiner reproducibility should be undertaken.

Facial landmarks detection is undoubtedly important in many applications in computer vision for example the face detection and recognition. In craniofacial anthropometry, consistent landmarks localization as per standard definition of the craniofacial anthropometry landmarks is very important in order to get accurate craniofacial anthropometry data. In this article we demonstrated an automatic detection of craniofacial anthropometry landmarks at the orbital region. 3D images of 100 respondents' were photogaphed using Vectra-3D in controlled environment. Craniofacial measurements of 30 3D images were measured using VAM software. Two data sets of left and right eyes positive training data were created to train 'en' and 'ex' haar cascade classifiers. These classifiers were used to detect and locate the inner (en) and outer (ex) eye corners. We automatically measured the left and right eye fissures length (en-ex), the intercanthal (en-en) and the biocular (ex-ex) width. Statistical analysis was performed on the measurements taken by Vectra 3D and by our software with paired t-test and calculated the ICC indices. We observed quite amount of false positive detections. We removed the false positive and predicted the eye corners. Our classifiers able to detect and locate the 'en' and the 'ex' in 59 out of 60 test images. Our results show accurate detection of 'ex' and 'en' craniofacial landmarks as per standard definition. The paired t-test showed that all four (4) measurements are no significant difference with the p values on 95% confidence level are above 0.05. The ICC indices for the measurements were from 0.4 to 0.78. In conclusion, our trained enHaar and exHaar cascade classifiers were able to automatically detect the 'en' and 'ex' craniofacial anthropometry landmarks in controlled environment. The measurements were clinically no significant differences with the mean different were less than 1 mm in both eye fissures and intercanthal except the biocular width ( 1.16 mm). The consistency of the measurements between the two methods are good for the intercanthal width and moderate for the biocular width and for both eye fissure lengths.