Influence of ambient light on the accuracy of different face scanning methods: an in-vitro study
Description
This study investigated the influence of different ambient light situations on the accuracy of various face scanning methods. The hypothesis was, that there would be no influence on the accuracy of the scanners. Four scanners were examined under 3 illumination levels (500 lx, 5000 lx, 20000 lx). A model of a human head was used as a test subject. A refrence scan of this model was created with an industrial CT. To examine trueness, the scans were compared to the refrence scan. The scan with the best trueness result for each scanner and illumination level, was employed as refrence in a following precision analysis. For all comparisons two alignment areas and two investigation areas were used. The results showed a scanner dependent influence of the ambient light. Therefore, the null hypothesis was rejected. The Face Hunter and Medit i700 showed their lowest results at an illumination level of 500 lx. But the trueness results of the Medit i700 showed only random differences between 500 lx and 5000 lx. The single-camera-photogrammetry showed lower RMSE-values under the brighter levels, with only random differences between 5000 lx and 20000 lx. No illumination level showed advantages over the others for the iPad's results.