In my last post I mentioned that we have some training coming up in this technology in December, and I want to explain a bit more about it.

I first learned about this technology from Bruce Zuckerman, PhD. He is a professor at USC and also the director of the West Semitic Research and Inscriptifact Projects. His work is fascinating – he and his team photograph ancient artifacts around the world, then attempt to read the writing on them. Their challenge is often very similar to what we face in forensic image analysis – having subjects with very little information, and trying to get everything one can out of them. Bruce has invited me to visit his facility a few times and has shown me their work, including their RTI work. One day I called and asked if he could give me a full demonstration of the RTI process. He agreed, and photographer Ken Zuckerman and Associate Director Marilyn Lundberg, PhD spent an afternoon with me, showing me the process, step-by-step.

Here’s a short description of that process. The camera is set up and remains stationary for 18 or more photographs. For each photograph, the light source is moved to a different location. Included in the photographs is a reflective sphere. It is essential that the camera, subject, and sphere remain stationary during the photography. These images are then processed with the RTI software. Once processed, one can view the subject; and by moving the cursor, the lighting changes. You see, not just the 18 separate images that were taken, but also all of the lighting ratios between them. And, you can also change the reflective quality of the surface of the subject, enabling the images to be additionally enhanced.

The advantage of this technology is that more detail can be seen in objects that have three-dimensional pattern marks – such as footwear impressions, tool marks, indented writing, obliterated serial numbers, tire impressions, etc. It is an excellent method to get more information from these subjects that are sometimes very elusive. There have been some forensic cases that have involved the use of this technology and an article has appeared about it in the Journal of Forensic Identification.

If you have an interest in this technology, I hope you’ll join us for the training we’re having in December. We’ve teamed up with Cultural Heritage Imaging (they have been providing training in RTI imaging to museums for several years). This will be a five-day training opportunity, specific for forensic uses of this technology. There is no guarantee that this workshop will be repeated – however, CHI does offer training in RTI on an ongoing basis.