3D modeling technology and lithic analysis at Wadi al-Hasa locality 623X, Jordan
Julien Riel-SalvatoreDepartment of Anthropology &
Archaeological Research InstituteArizona State University
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What is PRISM?
Partnership for Research In Stereo Modeling
3D Knowledge and Distributed Intelligence Project
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What’s the link b/w PRISM and refitting?
1) 3D perspective
2) Shape matching
3) Reduce time needed for refit
4) Data storage, sharing and management
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What is our goal?
Plainly put, we want to automate the lithic refitting process.
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What is lithic refitting?
Re-assembling pieces of rock that were sequentially removed from a core by prehistoric toolmakers.
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Why bother with refitting?
Problems currently associated with refitting
• Very time consuming and labor intensive
• Not useful for “big picture,” inter-site comparisons
• Focus is on expedient technologies
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Why bother with refitting?
“What do refitting studies tell us apart from the fact that we can do them and convince grant bodies to fund us?.... Have we in fact run out of things to do and questions to ask?”
- Gamble 1999: xx.
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Why bother with refitting?
“Refitting… can link artifacts together as behavior rather than simply assuming a relationship because they were recovered from a single level or from the same site”.
- Lindly et al. 2000: 211
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Why bother with refitting?
LITIHC REFITTING IS NOT AN END IN ITSELF!!
Its results and justification must always be linked to broader questions related to prehistoric human behavior
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Potential benefits of refitting
1) Understand prehistoric technology and economic behavior (how stone was used and managed)
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Potential benefits of refitting
2) Understanding taphonomy (archaeological site formation processes and post-depositional processes affecting the placement and morphology of artifacts)
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Potential benefits of refitting
3) Testing preconceived ideas about technology and typology and the relationship between the two (e.g., Volkman 1983, Marks & Volkman 1987).
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How are we going about it?
• Analyzing a bona fide archaeological assemblage that has previously been refitted
Locality 623X from the Wadi Hasa (Jordan), excavated by G.A. Clark (ASU) and colleagues
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Wadi Hasa 623X Cores
Total of 10 refitted cores; 5 used for this project.
Core C
33 pieces
Core H
6 pieces
Core A
16 pieces
Core E
23 pieces
Core F
7 pieces
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Why refitted material?
Using previously refitted cores because:
1) we know exactly which pieces are supposed to fit with which;
2) we have an estimate, in man-hours, of the time investment required by manual refitting to compare our results to.
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Digitizing Process
1) Scanning: On Cyberware M15 Laser Digitizer
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Digitizing Process
2) Generating 3D dataPoint cloud Triangulated mesh Smooth surface
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Digitizing Process
3) Cleaning up and decimation, using Raindrop Geomagic 4.0
Clean up extraneous triangles
Decimate clean scan (70K triangles)
Clean, decimated scan (10K triangles)
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Digitizing Process
4) Generating regions and boundaries, using Watershed; Watershed
threshold level can be adjusted for different degrees of resolution
Threshold = 0.12 Threshold = 0.085
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Digitizing Process
5) Generating analytically meaningful areas, using Region Editor
Volume (cm3) = 43.79348
Surface area (cm2) = 87.86601
Max length (cm) = 6.38181
Max width (cm) = 5.27742
Max height (cm) = 3.52001
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Digitizing Process
5) Generating analytically meaningful areas, using Region Editor
Selected region (Flake Scar 1- FS1)
Gaussian Curvature
Absolute Curvature
Mean Curvature
RMS Curvature
Kmax Curvature
Kmin Curvature Surface Area (cm2)
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So… does it work?
Sort of… One refit accomplished, but not very efficient.
15 minutes for ca. 1000 triangles, much user input.
Also, not realistic for archaeological pieces (1 to 1 match)
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So… does it work?
In reality, we are dealing with two objects that each have a number of surfaces that may refit only partially
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Promising new approach
Comparing series of point signatures on surfaces
Program designed by M. Bae
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Other Applications
Accurate measurements of specific areas on lithics that have never been accurately quantified (e.g., striking platforms)
Striking platform (highlighted in orange)
Region Area (cm2) = 0.80354
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Other Applications
Objective, accurate and tridimensional measures of artifact symmetry.
Cross-section Vertical
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Other Applications
Permanent, accurate, and flexible records of repatriated goods or those protected by National Antiquities Acts
Goblet and effigy pot housed at the Archaeological Research Institute, Arizona State University
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Future Research
Actual refitting remains top priorityOther measurements can nonetheless already
be put to profitable hypothesis-testing use
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Acknowledgements
NSF Grant IIS-998016 (3D Knowledge)NSF Grant BNS-8406601 (G.A. Clark)SSHRCC Grant 752-2001-0460 (J. Riel-Salvatore)Many heartfelt thanks to fellow PRISM team
members (M. Bae, D. Liu, P. McCartney, A. Razdan, A. Simon, M. Tocheri, D. Van Alfen, and others)
