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Figure 3 – uploaded byAlexandre Tokovinine

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Figure 3

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The surface of the artifacts presented certain challenges for the scanner. Some areas were slightly translucent or had high contrast (very light and very dark spots next to each other). Some textile fragments were reflective because of the protective coating used in conservation. The other sides of the eccentrics were  Figure B.3. Masking and its effects: (a) single scan with less masking; (b) single scan with more aggressive masking (CPN-P-2707/ Artifact 90-12).
The surface of the artifacts presented certain challenges for the scanner. Some areas were slightly translucent or had high contrast (very light and very dark spots next to each other). Some textile fragments were reflective because of the protective coating used in conservation. The other sides of the eccentrics were Figure B.3. Masking and its effects: (a) single scan with less masking; (b) single scan with more aggressive masking (CPN-P-2707/ Artifact 90-12).
more polished and reflective. Some of these challenges were overcome by using an average of eight captures for each scan and by scanning at a more oblique angle to reduce glare from the projector. Nevertheless, parts of individual scans contained substantial errors and had to be removed manually during process: ing. It was important to have enough overlap between the scans so that removal of bad sections would not cause gaps in the final model.
more polished and reflective. Some of these challenges were overcome by using an average of eight captures for each scan and by scanning at a more oblique angle to reduce glare from the projector. Nevertheless, parts of individual scans contained substantial errors and had to be removed manually during process: ing. It was important to have enough overlap between the scans so that removal of bad sections would not cause gaps in the final model.
The parameters of merging the scans into a single mesh also affected the  Figure B.5. Filling the holes in the mesh: (a) close-up of a 3D model edge with unfilled holes (visible as lighter or darker areas depending on the orientation of surface triangles); (b) close up of a 3D model with filled holes with some edge modification visible (CPN-P-2707/ Art. 90-12).  The processing of the data involved additional choices which were made with the goals of the project in mind. The first such choice was the extent to which the pixels along the edges of each scan and in the areas of high contrast had to be masked away. Less masking would result in a 3D surface with more data but potentially more errors (Figure B.3a). Aggressive masking would re- move some errors but also simplify the overall surface, particularly at the edges of the scans (Figure B.3b), which would nearly always correspond to the edges of the blades unless they faced the scanner so that both sides of the blade were visible during capture.
The parameters of merging the scans into a single mesh also affected the Figure B.5. Filling the holes in the mesh: (a) close-up of a 3D model edge with unfilled holes (visible as lighter or darker areas depending on the orientation of surface triangles); (b) close up of a 3D model with filled holes with some edge modification visible (CPN-P-2707/ Art. 90-12). The processing of the data involved additional choices which were made with the goals of the project in mind. The first such choice was the extent to which the pixels along the edges of each scan and in the areas of high contrast had to be masked away. Less masking would result in a 3D surface with more data but potentially more errors (Figure B.3a). Aggressive masking would re- move some errors but also simplify the overall surface, particularly at the edges of the scans (Figure B.3b), which would nearly always correspond to the edges of the blades unless they faced the scanner so that both sides of the blade were visible during capture.
Figure B.6. Meshlab-generated grayscale rendering of a 3D model with the radiance scaling filter to enhance the visibility of the surface topography (CPN- P-2707 / Artifact 90-12).  The finished 3D models were saved as PLY (Stanford Triangle Format) files with color information included. The scanner’s own Optocat software was used to make two-dimensional renderings of the models from several view angles with a simulation of multiple raking light sources. Larger images were obtained with free Meshlab software which offered additional filters to enhance the visibility of the surface topography such as radiance scaling (Figure B.6). All renderings were geometrically uniform and distortion-free orthographic views, which could be used for taking measurements and making accurate drawings of the artifacts. Meshlab was also used to downsample the digital models using quadric edge collapse decimation and convert them into U3D (Universal 3D) files, which could be embedded in 3D PDF documents.
Figure B.6. Meshlab-generated grayscale rendering of a 3D model with the radiance scaling filter to enhance the visibility of the surface topography (CPN- P-2707 / Artifact 90-12). The finished 3D models were saved as PLY (Stanford Triangle Format) files with color information included. The scanner’s own Optocat software was used to make two-dimensional renderings of the models from several view angles with a simulation of multiple raking light sources. Larger images were obtained with free Meshlab software which offered additional filters to enhance the visibility of the surface topography such as radiance scaling (Figure B.6). All renderings were geometrically uniform and distortion-free orthographic views, which could be used for taking measurements and making accurate drawings of the artifacts. Meshlab was also used to downsample the digital models using quadric edge collapse decimation and convert them into U3D (Universal 3D) files, which could be embedded in 3D PDF documents.
Related topics:
ArchaeologyMaya ArchaeologyLithic Technology (Archaeology)Lithic Analysis3D Laser Scanning (Archaeology)Structured Light
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