A virtual analysis of the precision and accuracy of 3-dimensional ear casts generated from smartphone camera images

Farook, Taseef Hasan; Rashid, Farah; Jamayet, Nafij Bin; Abdullah, Johari Yap; Dudley, James; Alam, Mohammad Khursheed

doi:10.1016/j.prosdent.2020.12.041

Cited by 14 publications

(14 citation statements)

References 16 publications

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“…Methods for aligning these digital assets are reliably accurate. 13,14 However, at this time, due to scanning technology limitations, the dynamic position of NHP cannot accurately be captured. Therefore, a properly oriented photograph appears to be the simplest and most efficient way to capture this reference position.…”

Section: Discussionmentioning

confidence: 99%

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Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position

Kois

Zeitler³

et al. 2022

Journal of Prosthodontics

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Although the evolution of digital technology continues to improve patient data acquisition, the ability to both standardize the recording of the maxillary occlusal plane and capture the necessary dynamic data for dento‐facial analysis remains elusive. This article describes step‐by‐step techniques to position the maxilla on an articulator using the natural head position and a facial reference system (Kois Facial Reference Glasses) for both analog and digital workflows. A photographic technique will be presented that captures the natural head position and allows the clinician to align a 2D reference photograph with the maxillary intraoral digital scan and the virtual articulator. Using this reference photograph, the clinician can record and communicate to the technician the maxillary arch position in relationship with the facial references, as well as transfer the additively manufactured casts in the same facial orientation for mounting and analysis either virtually or on an analog articulator.

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Section: Discussionmentioning

confidence: 99%

“…The software allows data from multiple sources, such as facial scans, intraoral scans, and CBCTs, to create layers in one image. Methods for aligning these digital assets are reliably accurate 13,14 . However, at this time, due to scanning technology limitations, the dynamic position of NHP cannot accurately be captured.…”

Section: Discussionmentioning

confidence: 99%

Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position

Kois

Zeitler³

et al. 2022

Journal of Prosthodontics

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“…e ., procedure to adjust color according to the light source available so that the color of the object appear natural within the photographs ) of the images. However, dental practitioners are generally limited by the inaccessibility to such professional tools and therefore take photographs without any added light modifiers [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

“…To mitigate these limitations, several investigators [7,8] have suggested the use of electronic strobe lights which are generally found within professional photo studios as these lights are able to correct the white balance (i.e., procedure to adjust color according to the light source available so that the color of the object appear natural within the photographs) of the images. However, dental practitioners are generally limited by the inaccessibility to such professional tools and therefore take photographs without any added light modifiers [9].…”

Section: Introductionmentioning

confidence: 99%

Color variations during digital imaging of facial prostheses subjected to unfiltered ambient light and image calibration techniques within dental clinics: An in vitro analysis

et al. 2022

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Background The study aimed to evaluate 1) the amount of color variations presents within clinical images of maxillofacial prosthetic silicone specimens when photographed under different clinically relevant ambient lighting conditions, and 2) whether white balance calibration (WBC) methods were able to mitigate variations in ambient lighting. Methods 432 measurements were acquired from standardized images of the pigmented prosthetic silicone specimens within different ambient lighting conditions (i.e., 2 windowed and 2 windowless clinics) at noon with no light modifying apparatus. The specimens were photographed once without any white balance calibration (raw), then independently alongside an 18% neutral gray card and Macbeth color chart for calibration in a post-processing (PPWBC) software, and once after camera calibration (CWBC) using a gray card. The LAB color values were extracted from the images and color variations (ΔE) were calculated after referring to the corresponding spectrophotometric values as control. Results Images in windowless and windowed clinics exhibited highly significant differences (p < 0.001) with spectrophotometer (control). CWBC demonstrated no significant differences (p > 0.05) in LAB values across windowed clinics. PPWBC using Macbeth color chart produced no significant differences for a* values (p > 0.05) across all clinics while PPWBC by gray card showed no significant differences (p > 0.05) in LAB values when only similar clinics (either windowed or windowless) were compared. Conclusion Significant color variations were present for maxillofacial prosthetic specimens owing to natural ambient light. CWBC and PPWBC using color charts were more suitable for color correction across windowed clinics while CWBC and PPWBC using gray cards had better outcomes across windowless setups.

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“…The issue of quantification and the need for reliable methods able to distinguish matches from mismatches remain fundamental in the topic of identification from video surveillance systems. From this point of view, the progressive diffusion of 3D image acquisition systems may provide an innovative contribution, being able to provide a threedimensional facial model, useful for further procedures of comparison [3,[9][10][11][12][13]. Therefore, techniques for 3D-3D superimposition need to be analysed in depth to verify the applicability of this novel technique of analysis to personal identification.…”

Section: Introductionmentioning

confidence: 99%

Improving 3D-3D facial registration methods: potential role of three-dimensional models in personal identification of the living

et al. 2021

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Personal identification of the living from video surveillance systems usually involves 2D images. However, the potentiality of three-dimensional facial models in gaining personal identification through 3D-3D comparison still needs to be verified. This study aims at testing the reliability of a protocol for 3D-3D registration of facial models, potentially useful for personal identification. Fifty male subjects aged between 18 and 45 years were randomly chosen from a database of 3D facial models acquired through stereophotogrammetry. For each subject, two acquisitions were available; the 3D models of faces were then registered onto other models belonging to the same and different individuals according to the least point-to-point distance on the entire facial surface, for a total of 50 matches and 50 mismatches. RMS value (root mean square) of point-to-point distance between the two models was then calculated through the VAM® software. Intra- and inter-observer errors were assessed through calculation of relative technical error of measurement (rTEM). Possible statistically significant differences between matches and mismatches were assessed through Mann–Whitney test (p < 0.05). Both for intra- and inter-observer repeatability rTEM was between 2.2 and 5.2%. Average RMS point-to-point distance was 0.50 ± 0.28 mm in matches, 2.62 ± 0.56 mm in mismatches (p < 0.01). An RMS threshold of 1.50 mm could distinguish matches and mismatches in 100% of cases. This study provides an improvement to existing 3D-3D superimposition methods and confirms the great advantages which may derive to personal identification of the living from 3D facial analysis.

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A virtual analysis of the precision and accuracy of 3-dimensional ear casts generated from smartphone camera images

Cited by 14 publications

References 16 publications

Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position

Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position

Color variations during digital imaging of facial prostheses subjected to unfiltered ambient light and image calibration techniques within dental clinics: An in vitro analysis

Improving 3D-3D facial registration methods: potential role of three-dimensional models in personal identification of the living

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