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CVPR 2011 Structured light · Detailed examples

Translucent Objects and Projector Defocus

Shower curtain scene: diffusion and inter-reflections.
Shower curtain scene: diffusion and inter-reflections.

The challenge

Recover the surface,
not optical artifacts.

Light diffuses through the curtain and reflects from the background, creating long-range optical interactions. The curtain is planar: ripples in the conventional reconstructions are spurious.

01 / Results

Reconstructing a shower curtain

Conventional Gray codes and phase shifting introduce large shape errors. Logical codes produce a nearly error-free reconstruction with the same number of input images as conventional Gray codes.

Conventional Gray codes, 11 images, and phase shifting, 18 images: spurious curtain detail.
Conventional Gray codes, 11 images, and phase shifting, 18 images: spurious curtain detail.
Our XOR codes · depth map · 11 images.
Our XOR codes · depth map · 11 images.

02 / Results

Reconstructing translucent materials

Highly translucent materials have a low direct-light component. Explicitly separating direct and global components, as in modulated phase shifting, can therefore give poor signal-to-noise ratio. The ensemble does not require that explicit separation.

Hollow wax candle: scene, modulated phase shifting (162 images), and code ensemble (41 images).
Hollow wax candle: scene, modulated phase shifting (162 images), and code ensemble (41 images).
Wax object: scene, modulated phase shifting (162 images), and code ensemble (41 images).
Wax object: scene, modulated phase shifting (162 images), and code ensemble (41 images).

03 / Results

Scanning with projector defocus

Defocus prevents high-frequency patterns in conventional Gray codes from being decoded reliably, reducing depth resolution and causing quantization artifacts. Similar effects can arise from imperfections in low-cost or pico-projectors. Large minimum-stripe-width codes avoid this loss of depth resolution.

Industrial parts scene.
Industrial parts scene.
Conventional Gray codes: quantized depth map and marked profile.
Conventional Gray codes: quantized depth map and marked profile.
Large minimum-stripe-width Gray codes: depth map and marked profile.
Large minimum-stripe-width Gray codes: depth map and marked profile.
Depth profiles: conventional Gray codes (red) and proposed Gray code (blue).
Depth profiles: conventional Gray codes (red) and proposed Gray code (blue).