Microscopic RTI

To fully appreciate the application of RTI in conservation practice, one should take into consideration conservation needs for limited human-object interaction, high quality and affordable visual analysis, microscopic levels of detail and advanced documentation. There is no doubt that methodological developments are necessary in order to meet those needs. One of the most obvious of these, even from the earlier stages of our research, was the microscopic level of detail required for conservation. Microscopic lenses are considered as an extension of the conservator’s eyes. Initially, the Highlight RTI method was tested under the microscope, which proved to be extremely difficult, due to the limited space available for setting up the scene, and considering the presence of the sphere, along with its shadows. Another disadvantage is the microscope arm, which excludes almost 25% of the lighting positions.

Based on the above observations, an experimental microscopic RTI dome was built, capable of capturing 64 microscopic images, four images from different angles to the object’s plane, from each of the 16 positions of the periphery of the dome. In addition, in order to enhance the captured data, the four lights were not placed in vertical order. The dome can be turned 90 degrees, in order to place the artefact securely on a stable plate. A metallic ring, joined with the dome, is located over the artefact plate. The metallic dome, equipped with four LED lights, is moving clockwise around the artefact’s plate. It is impossible for the moving dome and the ring to be separated or to touch the artefact. The microscopic dome gave exciting results. The construction of a more powerful, automatic and folding dome is under consideration.

Figure 1:The mini-dome
Figure 2: The microscopic dome in use
Figure 3: Ceramic roundel, burned, cracked with losses and minor remnants of gold decoration, Derveni, tomb A (diam. 3cm). Clockwise from top left, digital image, RTI visualization and microscopic RTI visualization of 1.5 mm. The ceramic roundel is located in the Archaeological Museum of Thessaloniki.


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