April 10 Workshop: the Final Day.


On our last official day of the workshop we returned to a operating two camera, my D300S and Alex’s new D700.  Among our first goals was to finish imaging the weathered side of a stone that we had failed to adequately image due to a poor light distribution.

Here are the results from the Victor Dupont monument:

The decoration is now clearly visible under specular enhancement and can be compared to the better preserved reliefs on the other side. Note particularly the vegetative relief at the top of the monument.

While Alex was at work on the Dupont stone, I took an experienced team to work on a heavily weathered marble monument on the other side of the stream:

Notice that we are no longer using a laptop with the D300s and are instead relying on an external IR remote to trigger the shutter. Here are the results:

While the surface normals were within bounds on the capture, the veinous character of the marble weathering made reading the inscription difficult under specular enhancement. Considerable post processing will be necessary to reveal all the characters.

Alex’s group then moved out towards Sydenham Rd. where we had early found a small immigrant plot. Hitherto we had only imaged English-language monuments but thought it was important to capture the Asian monuments at the cemetery before the end of the project.

In many cases, these small, inexpensive stones were in the most desperate need of recording. They were insecurely fixed in the ground and their low height meant that they were more subject to damage than the larger, elevated monuments elsewhere. Here are the initial results:

Despite the fact that it was virtually impossible to get a good distribution of light positions due to the fact that the stone was so close to the ground, Alex and his crew did a fantastic job. The normal visualization above shows that apart from a small area on the bottom, the surface normals were perfectly captured. Catrina Caira, a MAC student and among our most dedicated RTI students, was on hand to help us with the Chinese. She determined, with some help from a friend, that the date of death of this individual was 1926.

Here was the next stone in the plot:

In this case the script was virtually invisible to the naked eye. Again, Alex and his team did a great job of capturing the normals despite the physical constraints, as the following visualization shows:

Here Catrina again helped us with a transcription. More on these Chinese stones in the future!

My own final capture was a more traditional Cataraqui stone:

Despite some lichen on the monument the specular enhancement was especially impressive:

Some more post-processing will be necessary for a full transcription, but we were very pleased with the results. Again, the surface normal visualization proved an accurate guide to the location of the lichen growth on the monument:

This stone proved to be lots of fun in post processing.

It was definitely gratifying (and humbling) to see our students picking out names and dates from the RTIs much faster than their teachers. A very promising start to RTI at Queen’s University!

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3 Comments

Filed under On Site Work, Research, RTI

3 responses to “April 10 Workshop: the Final Day.

  1. Hello, great site and workshop description. Have ye used RTI on horizontal ledger stones? Or table/box tombs?

    • Some of the stones imaged in this workshop were flat on/in the ground. We have also imaged many horizontal artifacts with size limited by spacial resolution. Very large artifacts can receive one overall RTI and detailed RTIs can be carried out in areas of interest.

      • Ok tx. I have been studying the photographs to deduce the methodology. Have asked our technical workmate (GIS/Drupal/Photography) to look into RTI. The technique ye have developed will get a lot of interest here in Ireland and we will stay in touch.

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