Photogrammetry

Photogrammetry is an image-based 3D technology. At its simplest, it is the processing of 2D image data from standard photographs into 3D data. The technique is based on the principles of human vision and depth perception and the overlapping of stereoscopic images (Matthews, p.9). While not a new technique, it presents an approachable and accessible technique for cultural heritage professionals to acquire 3D data. Advances in consumer level digital cameras and computing power along with processing algorithms have dramatically increased this technique's usability in the past several years.

Being based on still images from a digital camera, photogrammetry presents a less expensive, convenient and more flexible option for the production of 3D models of real-world objects or scenes. Equipment can easily be updated and/or resolution increased with a new camera and/or computer instead of replacing the entire system and software needed. A backup can be on hand in the field by just having a second camera available making this a very flexible technique.

Photogrammetry Resources

Cultural Heritage Imaging (CHI): Photogrammetry

Georgia O'Keeffe Museum: Introduction to Photogrammetry

Koutsoudis, Anestis, Blaz Vidmar, and Fotis Arnaoutoglou. "Performance Evaluation of a Mult-image 3D Reconstruction Software on a Low-feature Artefact." Journal of Archaeological Science 40 (2013): 4450-456.

Matthews, N. A. 2008. "Aerial and Close-Range Photogrammetric Technology: Providing Resource Documentation, Interpretation, and Preservation." Technical Note 428. U.S. Department of the Interior, Bureau of Land Management, National Operations Center, Denver, Colorado.

3D Scanning

The recent proliferation of commercial three-dimensional digital scanning devices has made 3D scanning--and virtual and physical replication--a practical reality in the field of heritage preservation. 3D scanning produces a high-precision digital reference document that records condition, provides a virtual model for replication, and makes possible mass distribution of digital data. In addition to research, documentation, and replication, 3D data of artifacts are increasingly being used for museum collections storage and packing designs. The cost and complexity of 3D imaging technologies have made 3D scanning impractical for many heritage institutions in the past, but this is changing, as an increasing number of commercial systems are being tailored and marketed for heritage applications.

One of the most direct benefits of the technology is that no physical contact is made with the object while scanning. Measurements are more accurate, and new, more valid comparisons can be drawn. More importantly perhaps, when replication is desired, common risks from mold making are not incurred. No barrier coating or subsequent cleaning is necessary. It is still difficult to produce a physical replica from this data, but as with other new technologies, advances continue to come quickly.


 

Sequential patterns projected by structured light scanner on the surface of a crab-eater seal during scanning. Distortion of linear scan patterns is processed to generate spatial data.

Further Reading

Wachowiak, Melvin J. and Karas, Vicky. 2009. "3D Scanning and Replication for Museum and Cultural Heritage Applications." Journal of the American Institute for Conservation, 48 141–158.

This paper presents a review of the current state of 3D imaging in the cultural heritage field, methods of physical replication, the different systems used in heritage applications, criteria for choosing a system, and the techniques used for working with the data. Attention is given to identifying those objects that are not likely to be suited for 3D scanning.

Wachowiak, Melvin J., Karas, Basiliki Vicky, and Baltrusch, Robert E. 2009. "Reconstruction of a Nineteenth Century Plaster Piece Mold and Recreation of a Casting." In Computer Applications to Archaeology 2009, Williamsburg, Virginia, USA, March 22-26, 2009. 8.

See How 3D Scanning Ties Into Smithsonian Exhibits