Stomatology ›› 2023, Vol. 43 ›› Issue (12): 1057-1064.doi: 10.13591/j.cnki.kqyx.2023.12.001

• Basic Research •     Next Articles

Automated photogrammetric analysis from a 2D photograph by convolutional neural network

QIU Tao1,HE Tao2,ZHANG Qiang2,XIAO Yuxuan1,GUO Weihua1,3()   

  1. State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
  • Revised:2023-08-01 Online:2023-12-28 Published:2023-12-28
  • Contact: GUO Weihua E-mail:guoweihua943019@163.com

Abstract:

Objective To develop an automatic system to simplify the progress based on convolutional neural networks and build its accuracy evaluation system. Methods A total of 467 lateral and frontal views (age range: 6-55 years) were collected. Forty-five landmarks were detected in the front view and so as 31 in the profile. An automatic locating system based on CNN was developed, consisting of a global detection module and a local correction module. An accuracy evaluation system based on aesthetic considerations was proposed, which consisted of the standardized average error (NME) of the detected points, success rate (SDR) of landmark locating within the unit distance and the successful classification rate (SCR). Results The NME of our test set was 0.079±0.221 in profile and 0.025±0.021 in frontage.The SDR of 0.02, 0.04, 0.06, 0.08 and 0.10 units were respectively 54.17%, 85.71%, 93.94%, 96.69%, and 97.37% in profile, 58.54%、87.59%、95.64%、98.03%、99.00% in frontage. Most of their SCR of our test set were 100%. Conclusion In this study, we successfully proposed an automatic landmark locating system based on CNN. The system can detect 76 landmarks with high detection accuracy within 20 seconds. Moreover, we constructed an evaluation metric of the automatic landmark locating system which focused on the facial aesthetics. Both the location and evaluation system can highly simplify the photogrammetric analysis.

Key words: photogrammetric analysis, convolutional neural networks, facial aesthetics

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