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Surface Topography of Cuneiform Tablets

Surface Topography of Cuneiform Tablets. Monica Barbu* and Robert H. Johnston, and Jonathan S. Arney Chester F. Carlson Center for Imaging Science Rochester Institute of Technology. Overview. Background Theory Accomplishments Summary. Cuneiform Tablet. First form of writing.

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Surface Topography of Cuneiform Tablets

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  1. Surface Topography of Cuneiform Tablets Monica Barbu* and Robert H. Johnston, and Jonathan S. Arney Chester F. Carlson Center for Imaging Science Rochester Institute of Technology

  2. Overview • Background • Theory • Accomplishments • Summary

  3. Cuneiform Tablet • First form of writing. • 5cm.length 4cm.wide 1cm.high. • Evolved from pictographs. • Used as documents about property, inventory and taxes. • Consist of wedge marks and cylinder seal impressions.

  4. The Challenges of Photographing Cuneiform Tablets • Transfer 3-dimensional characteristics to a 2-dimensional plane. • In the past: • Artists hired to draw the features - time consuming and subjective. • Nearfield microscopy - expensive. • Proposed technique: • Surface Topography - simple equipment and inexpensive.

  5. Surface Topography

  6. Surface Topography • Calculating the topography of an object from digital images is a distinct way of extracting contour measurements. • Described as variation in height across a horizontal dimension. • Results in the quantitative relationship between surface angle and the observed irradiance in the camera.

  7. Surface Topography • Provides relationship between topography and irradiance. • The surface of the object is a Lambertian reflector.

  8. Schematic representation between topographic height, h and the surface angle, 

  9. Surface Topography Characteristics of the two images in one dimension is: I1(x) = IoR sin [01 + (x)] I2(x) = IoR sin [02 + (x)]

  10. Capturing images with novel device • One light source attached to a graded arc. • The arc has the ability to be positioned at any degree from the base. • The arc is attached to a ring which is free to move 360º around the object. • The object is stable in the center of this ring.

  11. Capturing the Images

  12. Flat Fielding • Calibrate the camera, in order to use the digital camera as a primary instrument for measuring light. • Flat fielding the images. • Removes the side to side variation in brightness which is caused by non-uniform illumination. • The result consists only the random variations caused by the surface of the object.

  13. Surface Topography of the Sphere

  14. Results • Matrix of alpha values • Scaled to 256 gray levels. • 1-dimensional array across the center of the sphere extracted for analysis.

  15. Trace of Tan(alpha) Values Calculated Across the Row of Pixel Values in the “Scan” Line

  16. Topographic Height Across the “Scan” Line

  17. Surface Topography of Cuneiform Tablet Before After

  18. Topographic Height Across the “Scan” Line from the Cylinder Seal Impression

  19. Unfolded Tablet

  20. Conclusion • Cuneiform Tablets are remains of historic cultural values. • Surface topography would be beneficial in characterizing the evolution of these artifacts. • Make these documents more accessible. • Offer a clue to the specific tools used to make the impressions.

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