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Trials with EA114. |
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Overview New to 3D scanning? For an overview of laser scanning in general, click here. Overview Under the direction of Dr. Nigel Strudwick of the British Museum’s Egyptian Antiquities Dept., several of the museum’s holdings were documented in March 2000. In the case of artifact EA144, used here as an example, scans were taken from five distinct viewpoints. Observing the subject in plan view (right), these scan viewpoints are mapped below: |
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Digitizing from the BM Collection We digitized several
objects while at the British Museum, including the artifact below. |
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Selecting Viewpoints In selecting viewpoints, the goal is to describe the scan subject completely, while maintaining common objects between views to register the resulting data. Here, the first four views (noted as v0 – v3) were rotated approximately 90, 180, 270, and 360 degrees around the subject. For these views, the scanner was slightly inclined. Each color-coded viewpoint required a new orientation of scanner to the subject. The resulting data from these viewpoints is expressed at right. These views show the "cloud of points" generated, distinct spatial points on the surface of the sculpture. Here, each view is comprised of approximately 15,000 individual points. For important details, sub-viewpoints were designated and scanned at higher resolution (i.e., the areas around the eyes and faces were scanned at 0.2 mm resolution.) Note that each viewpoint shown contains only a fraction of the total information for the subject. Just as a light projects a region of shadow on an object, here each view contains areas where data is "shadowed." In order to register the data from multiple viewpoints, spheres of known diameter were included in the scanned scene. Since these spheres appear the same from any view and are uniform in diameter, they can be isolated by the computer, named, and treated as distinct objects. |
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Integrating the Data Shown below are three
views of the "cloud of points" generated from multiple scans. |
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Registering the Results
In both
viewpoints below, the spheres (#4 and #5) are placed to the left and center of the
subject. Because the views were designed with a view to the same spheres,
it was possible to register the coordinate space of each separate viewpoint
into an integrated model. Note: since three
common objects are required for this type of registration, components of the
sculpture and its stand were used as "surrogate spheres” for registration
purposes. |
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 Spheres are shared between viewpoints v0 and v1..
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A Detailed 3D Model After locking together each of the views, the resulting cloud of points can be visualized in a variety of ways, including final rendered files. Here, the model is expressed as pure points to show the areas in which viewpoints overlap. |
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A fully
integrated cloud of points, including