title: New approach to accuracy verification of 3D surface models: An analysis of point cloud coordinates.
abstract: OBJECTIVE
  The precision of two types of surface digitization devices, i.e., a contact probe scanner and an optical scanner, and the trueness of two types of stone replicas, i.e., one without an imaging powder (SR/NP) and one with an imaging powder (SR/P), were evaluated using a computer-aided analysis.
  
  
  METHODS
  A master die was fabricated from stainless steel. Ten impressions were taken, and ten stone replicas were prepared from Type IV stone (Fujirock EP, GC, Leuven, Belgium). The precision of two types of scanners was analyzed using the root mean square (RMS), measurement error (ME), and limits of agreement (LoA) at each coordinate. The trueness of the stone replicas was evaluated using the total deviation. A Student's t-test was applied to compare the discrepancies between the CAD-reference-models of the master die (m-CRM) and point clouds for the two types of stone replicas (α=.05).
  
  
  RESULTS
  The RMS values for the precision were 1.58, 1.28, and 0.98μm along the x-, y-, and z-axes in the contact probe scanner and 1.97, 1.32, and 1.33μm along the x-, y-, and z-axes in the optical scanner, respectively. A comparison with m-CRM revealed a trueness of 7.10μm for SR/NP and 8.65μm for SR/P.
  
  
  CONCLUSIONS
  The precision at each coordinate (x-, y-, and z-axes) was revealed to be higher than the one assessed in the previous method (overall offset differences). A comparison between the m-CRM and 3D surface models of the stone replicas revealed a greater dimensional change in SR/P than in SR/NP.
authors.affiliation: Department of Public Health Science, Graduate School, Korea University, Seoul, Republic of Korea.
authors.forename: Wan-Sun
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Department of Public Health Science, Graduate School, Korea University, Seoul, Republic of Korea.
authors.forename: Jong-Kyoung
authors.initials: JK
authors.lastname: Park
authors.affiliation: Department of Public Health Science, Graduate School, Korea University, Seoul, Republic of Korea. Electronic address: kjh2804@korea.ac.kr.
authors.forename: Ji-Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Public Health Science, Graduate School & BK21+ Program in Public Health Science, Korea University, Seoul, Republic of Korea.
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Kim
authors.affiliation: Department of Public Health Science, Graduate School, Korea University, Seoul, Republic of Korea.
authors.forename: Woong-Chul
authors.initials: WC
authors.lastname: Kim
authors.affiliation: Department of Dental Laboratory, Masan University, Gyeongsangnam-do, Republic of Korea.
authors.forename: Chin-Ho
authors.initials: CH
authors.lastname: Yu
mesh_terms: D017076:Computer-Aided Design; D003735:Dental Casting Technique; D003761:Dental Impression Technique; D017266:Dental Prosthesis; D003779:Denture Design; D006801:Humans; D003765:Models, Dental; D066330:Printing, Three-Dimensional
keywords: 3D surface model; Accuracy; Point cloud; Precision; Trueness