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Measurement error using a SeeMaLab structured light 3D scanner against a Microscribe 3D digitizer
Dolores Messer1, Michelle S Svendsen2, Anders Galatius3
1Department of Applied Mathematics and Computer Science, Technical University of Denmark, Kongens Lyngby, Denmark.
Structured light scanners offer precision comparable to digitizer arms in geometric morphometrics. While both methods have errors, scanners provide detailed 3D models and may reduce between-operator error, making them suitable for complex studies.
Area of Science:
- Geometric morphometrics
- 3D imaging technologies
- Comparative morphology
Background:
- Geometric morphometrics quantifies shape variation using landmark data.
- 3D digitizer arms and structured light surface scanners are portable tools for this field.
- This study compares a SeeMaLab structured light scanner to a Microscribe 3D digitizer arm.
Purpose of the Study:
- To assess measurement error and bias between a structured light scanner and a digitizer arm.
- To compare the precision and reliability of landmark data acquisition using both devices.
- To investigate the impact of operator and device on morphological measurements.
Main Methods:
- 31 anatomical landmarks were placed on 22 grey seal skulls using both a digitizer and a structured light scanner.
- Each skull was scanned twice, with landmarks annotated twice by two operators for each device.
- Procrustes ANOVAs were used to analyze within- and between-operator error, device-induced error, and scanning-related error.
Main Results:
- Both devices achieved similar precision, with the scanner potentially offering higher precision if difficult landmarks are excluded.
- Between-operator error was smaller with the scanner, though systematic differences between devices were observed, primarily at less defined landmarks.
- Device, operator, and landmark replica were significant but minor sources of variation compared to biological variation.
Conclusions:
- Structured light scanners are recommended when detailed 3D models are beneficial, offering comparable precision to digitizers.
- Pre-study identification of difficult landmarks is crucial for maximizing precision.
- Data from different devices/operators should not be combined without validation due to potential bias, especially with low biological variation.
- Scanner pipelines are better suited for studies involving multiple operators, with minimal scanning-related error when protocols are followed.
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