3D Scanning in the Presence of Specularities
Here, we show several examples of 3D scanning in the presence of specularities. In each case, the 3D scanning technique used was phase-shifting of sinusoidal patterns. By clicking on each of the thumbnail images shown below, you can see the corresponding high resolution image.
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Metal Hemisphere
Method: Phase-Shifting

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Glossy Metal Hemisphere

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Input Images

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3D Reconstruction


Conventional structured light [large exposure]
 


Conventional structured light [medium (best) exposure]
 


Conventional structured light [small exposure]
 
Left column shows input images for conventional SL under large (1.6s), medium (1.0s) and small (0.3s) exposure settings, respectively. Each of these sequences includes strong (saturated) specularities, dark (noisy) regions, or both. Right column shows the corresponding reconstructed shapes. At high exposures, regions with specular highlights are not reconstructed due to saturation. At low exposures, some scene regions are too dark to be reconstructed reliably.
 

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Input Images

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3D Reconstruction


Diffuse structured light [best exposure]
 
With the diffuser, the specularity is spread out and weakened in the input images. Also, the intensity of the points near the base plane is increased. Because of this, a higher quality reconstruction is achieved.
 
Coin
Method: Phase-Shifting

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Scene

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Conventional Structured Light

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Diffuse Structured Light
Reconstructions using best exposures for both conventional and diffuse SL, respectively. Profile views of the reconstructions are shown. Since the coin is specular, conventional SL results in depth errors (large spikes) due to specular highlights and low signal-to-noise ratio. With the same number of input images, diffuse SL produces the correct reconstruction (flat).
 


Alternate view-point renderings of the reconstructions using diffuse SL.
 
Earring
Method: Phase-Shifting

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Scene

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Conventional Structured Light

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Diffuse Structured Light
The earring is made of polished (specular) copper. Reconstructions using best exposures for both conventional and diffuse SL, respectively. Because of specularities, conventional SL results in holes. With the same number of input images, diffuse SL produces a higher quality reconstruction.
 
Knife Edge
Method: Phase-Shifting

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Scene

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Conventional Structured Light

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Diffuse Structured Light
The knife blade is made of polished stainless steel. Conventional SL results in erroneous reconstructions due to specular highlights and low signal-to-noise ratio. Reconstruction using diffuse SL is nearly error-free.