Close Range Photogrammetry Technique:: A validation study on craniofacial soft tissue measurement

In this study, the alternative non-contact measuring method, close range photogrammetry technique was used to measure human facial ladmarks. The validity of this method was then tested by comparing to the direct measurement method. 32 male adults with normal facial appearance were included in this study as the subjects for both methods. The differences in measurements between the two methods for 6 dependent variables were calculated using paired student t-test. Through the study it was found that the agreement between the two methods was excellent, yielding correlation coefficient between 0.887 and 1.09. No evidence of difference was found in 4 measurements (P>0.05), which were not involved with the hairy surface. Approximately 95% of the indirect method measurements are within 3.5mm of the direct measurements, and 95% are within 3.0mm when the 2 measurements of the hairy surface were excluded. The findings suggested that the close range photogrammetry technique is a reliable method in measuring facial landmarks in both linear and curve measurements.