Cultural Heritage Imaging


RTI Experimentation with a Copper Breastplate in the Florida State Bureau of Archaeological Research by marlinlum

This is a Guest Blog by Photographer Joseph Gamble.

As an affiliate with the University of South Florida’s Alliance for Integrated Spatial Technologies, I traveled with a team of archaeologists doing imaging research and 3D laser scanning of artifacts to Tallahassee last year to work in the Florida State Bureau of Archaeological Research (BAR) and experiment with RTI on a number of Native American artifacts from Lake Jackson, Florida. AIST Directors, Drs. Travis Doering and Lori Collins along with AIST archaeologist Dr. Jeff DuVernay, helped me to manage a challenging RTI of a Native American copper breastplate as well as other copper and metal objects from Lake Jackson and several other Florida sites.

Native American copper breastplate from Lake Jackson, Florida

The artifacts were from the ancient Lake Jackson settlement, a civic-ceremonial center of a Mississippian chiefdom that flourished across parts of northern Florida between c. 900-1500 A.D. The breastplate (23 X 54 cm) was cold-hammered from a sheet of native copper and contains extensive iconographic and symbolic that today are faint and difficult to discern. In the 1970s, the piece was encased in a clear Plexiglas, cube-like chamber that had been infused with argon gas as a conservation measure to halt corrosion of the artifact. The reflective polymer barrier that enclosed and protected breastplate seemed to pose an insurmountable obstacle for its accurate high resolution documentation. To stabilize the breastplate it had also been pressed into a plaster base to prevent further fragmentation and distortion leaving the piece with a cracked or crenelated surface texture. This condition was an additional for the documentation because of the shadowing that further limited the usability of the image set.

To acquire an inclusive data set that would contain sufficient usable images to build an RTI, we placed the case on black velvet, mounted the black balls and commenced to shoot. The total image count came to 156 raw files of which 57 were used to build the RTI file and, much to our delight, it worked well.

View the Final RTI File by clicking here (you tube video).

Joseph Gamble is a previous 4-Day RTI Training graduate. You can learn more about Joseph Gamble Photography at: http://www.jcgamble.com/

You can learn more about the Alliance For Integrated Spatial Technologies at: http://aist.usf.edu/

Advertisements

2 Comments so far
Leave a comment

Hello everybody,
I was just browsing around when I found some videos on the RTI-technique by chance. This seems to be a great tool for archeology and conservation. One thing I was wondering about is: Is RTI able to produce true 3D-Data like laser scanners or Structured-light 3D scanners are? And are there any restrictions concerning the surface of the object (for example how about transparent, glossy or very bright/dark surfaces)?

Comment by Alex

RTI create normal fields sometimes called RGBN (RGB + normals) data. You can read more about that on our web page for RTI (http://culturalheritageimaging.org/Technologies/RTI/) while this type of data can be integrated into a 3D mesh, there are some issues with doing so.

RTI can work well with shiny material (such as gold or silver) and also with dark material (such as ebony) and bright material (such as paper and ivory), but not transparent material. Some translucent material also works, it depends somewhat on the surface.

LEarn more on the CHI website, or you might also want to look at an article we recently had in the ASiS&T Bulletin that includes some examples: http://culturalheritageimaging.org/What_We_Do/Publications/asis-article/

Comment by cdschroer




Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s



%d bloggers like this: