Differences in engineers' brain activity when CAD modelling from isometric and orthographic projections.

A way of presenting information in visual representations of technical systems influences the progress and the outcome of the engineering design process. Consequently, improving the means by and through which information is utilised during the process is one suggested approach to advancing engineering design. Engineers' interaction with visual representations of technical systems is mainly visual and virtual. Although such interactions are cognitively complex, little is known about cognition (mental information processing) underlying the utilisation of design information during engineering design. To narrow the research gap, this study explores how visual representations of technical systems affect engineers' brain activity while generating computer-aided design (CAD) models based on them. More precisely, the brain activity of 20 engineers is captured and analysed using electroencephalography (EEG) during the visuospatially-intensive design tasks of CAD modelling in two conditions; when technical systems are presented with orthographic and isometric projections in technical drawings. The results imply the sensitivity of engineers' brain activity in CAD modelling to the visual representation from which a technical system is interpreted. In particular, significant differences are found in theta, alpha, and beta task-related power (TRP) over the cortex when interpreting the technical drawings and CAD modelling from them. Furthermore, the results reveal significant differences in theta and alpha TRP when considering the individual electrodes, the cortical hemispheres, and the cortical areas. In particular, theta TRP over the right hemisphere and the frontal area seems essential in distinguishing neurocognitive responses to the orthographic and isometric projections. As such, the conducted exploratory study sets the foundations for exploring engineers' brain activity while performing visuospatially-intensive design tasks, whose segments are relatable to the aspects of visuospatial thinking. Future work will explore brain activity in other design activities that are highly visuospatial, with a larger sample size and an EEG device of a higher spatial resolution.

Accuracy Analysis of Extraoral 3D Scanning in the Development of Dental Prosthetic.

Objective: The study has evaluated the accuracy (trueness and precision) of seven extraoral scanners when scanning two different types of jaws: simplified jaw with sharp edges and abutments and realistic jaw with natural teeth. The accuracies of extraoral scanners were compared, and their compliance with the required clinical accuracy levels was discussed. Material and methods: Ten scans were made with each scanner for both models. The comparison of the selected dental scanners relied on reference scans made for both models. Trueness, precision, and the distribution and value of laboratory scan points' deviations were assessed for each scanner across the models. Results: The trueness for the model of the simplified jaw with abutments ranged from 16.15 to 49.78 µm. The measured precision values for the same model ranged from 4.33 to 29.49 µm. For the model of the realistic jaw with natural teeth, the trueness results ranged from 11.32 to 24.55 µm, while the obtained precision values were between 2.29 and 18.06 µm. Conclusion: The revealed dissimilarities in the accuracies of scanners and their ranking when scanning different models lead to the conclusion that model selection is critical for the research design. All the scanners met the clinical accuracy requirements and are suitable for use in laboratories for scanning jaws with abutments and jaws with natural teeth. However, the accuracy values reported by the manufacturers of scanners are better than those obtained in this study. Furthermore, the results suggested that blue light scanners outperform white light and laser scanners.