Feasibility study of using optical moir?? interferometry technique for fine-grain surface relief in heritage recording.



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Texas A&M University


In order to prepare for the prospective need for heritage 3D recording, the main objective of this research was to investigate a new depth measuring method that can reduce identified limitations of current point-to-point measuring approaches. The limitations were time-money consumption, intrusiveness, accuracy assumption and efficiency. In many disciplines other than heritage recording, optical moir?? interferometry techniques (OMIT) are well developed as a measuring method and are considered fast, non-intrusive, accurate, and efficient. Based on these considerations, this research hypothesized that OMIT, as a measuring method, is feasible with respect to time-consumption and accuracy in acquiring depth measurement for fine-grain surface relief for historic recording. To test this hypothesis, a feasibility investigation was carried in which OMIT was used for surface relief topographic recording. This goal was approached by performing a comparison study between the OMIT measuring method as the investigated method and the hand measuring method as the control method. For each method, the comparison required performing eight experimental samplings of relief recording for a pre-designed physical model surface. The data collected from the hand measuring samples were the depth measurements of predefined points on the model surface and the timeconsumption for both measuring and data preparing processes. The data collected from the OMIT measuring samples were moir?? dark fringes generated on the model surface and the time-consumption for both moir?? generating and data preparing processes. For measurement accuracy evaluation, the collected depth data were prepared in the form of topographic contour drawings. For the OMIT feasibility evaluation, a comparison was carried out to examine the resulting topographic contour drawings for depth measurement accuracy level and measuring process time-consumption. In conclusion, the OMIT method showed higher depth measurement accuracy levels and lower process time-consumption than the hand method. The OMIT method also demonstrated less intrusiveness and more efficiency. This superiority validates the feasibility of using fine-grain surface relief for heritage recording purposes. Finally, the observed advantages of the OMIT method were presented to establish potentials for future developments and investigations. The observed limitations of the method were also pointed out to establish trends for recommendations and further studies.