About The Met/ Conservation and Scientific Research/ Conservation and Scientific Research Projects/ Illumination of Material Culture: A Symposium on Computational Photography and Reflectance Transformation Imaging (RTI)/ Day 1: Afternoon Session

Day 1: Afternoon Session

 

Presentations

[Video: 00:50]

Conservation imaging is an important part of the examination and documentation of works of art. At the American Museum of Natural History, where we work on diverse collections, we face many documentation challenges that require creative problem solving. My fellowship research has involved trouble-shooting some of these issues and investigating computational photography techniques to determine when their use may be appropriate. Examples include photographing large totem poles in the gallery in visible and ultraviolet illumination, and understanding and documenting shallow surface incisions in different materials (stone, birchbark).

[Video: 5:55]

The presentation is about the making of the never-before-seen Rollout RTI of a Maya Vase.

[Video: 9:50]

I discuss the application of RTI to ancient graffiti in Herculaneum, Italy. Unlike most modern graffiti, ancient graffiti were inscribed into wall plaster, which makes them difficult to photograph with normal photography techniques. Though not without its challenges, RTI is a better method of capturing these inscriptions.

[Video: 15:15]

This lightning talk focuses on a case study at the National Museum of New Zealand Te Papa and centers on the imaging documentation and digital/physical repatriation of a Maori meeting house called Te Hau Ki Turanga. The partnership between museum conservators and local Rongowhakaata community members will give a productive locus for which to discuss hybrid approaches to preservation in both tangible and intangible heritage.

[Video: 21:10]

Ongoing research in the Nels Nelson North American Archaeology Lab at the American Museum of Natural History has recently explored use of RTI to help us record and visualize decorative modifications to stone and shell artifact surfaces. The technique illuminates otherwise subtle stylistic incisions and pits, allowing archaeologists to distinguish intentional modifications from incidental alterations to an artifact's surface. RTI particularly helps us define "object itineraries" that track individual artifact movements by identifying superpositions of marking sequences of motif, potentially identifying incidence of embedded symbols across time and space. In this talk we compare the results of MicroCT scans with RTI imagery used to illuminate decorative features on Mississippian shell gorgets from the Georgia coast and incised stone artifacts from throughout the Great Basin. We conclude that MicroCT's time-intensive processing makes RTI an attractive, open source, and DIY alternative. Side-by-side comparisons demonstrate the utility of RTI but also call attention to shortcomings experienced with the GUI export of publication-quality images.

[Video: 25:15]

Details of an inexpensive DIY RTI dome system are presented. The design supports up to 64 1A/3W LEDs, which allow for domes from 12" to over 1 meter in diameter. The smaller dome is fully portable, capable of battery operation, and can be operated in the field. A small RTI dome system can be built for less than $500. The design is Open Hardware, software is open source, and documentation is Creative Commons; all are available online.

Links

HACKADAY.IO Affordable Reflectance Transformation Imaging Dome
Reflectance Transformation Imaging For Lithics

[Video: 30:25]

Orthogonal projections of objects play an important role in the process of making archaeological illustrations. We present a method to generate the detailed orthogonal projection of a 3D model by fusing normal and texture information in gradient domain. We first render the model into a texture image from a perpendicular view. A normal map is then obtained from the same view with pseudo-colors converted from vertex normals. Finally, we make a non-photorealistic projection image that combines the texture image and the normal map by solving the 2D-screened Poisson equation. The non-photorealistic projection is both geometry-aware and texture-aware and enhances the subtle details that are hard to see in the texture image or the normal map alone. It is more convenient for archaeologists to make line drawings by using tools such as Adobe Illustrator to trace over the fused images.

[Video: 35:35]

The capture of RTI data can present some inherent photographic and safety complexities for artwork and the objects being documented. Presented in this lightning talk are some unique DIY solutions to ensure object safety and high quality data.

Invited Speakers

[Video: 47:20]

[Video: 1:11:50]

[Video: 1:34:30]

[Video: 1:52:05]