A Dual Light Stage
A Dual Light Stage
2005 Eurographics Symposium on Rendering
Tim Hawkins     Per Einarsson     Paul Debevec
USC Institute for Creative Technologies

Reconstructed images of a metal bowl formed by scanning a laser beam across the bowl and
observing the light scattered onto a surrounding diffuse surface. The scattered illumination
has been modulated by three lighting environments from the light probe image gallery.



We present a technique for capturing high-resolution 4D reflectance fields using the reciprocity property of light transport. In our technique we place the object inside a diffuse spherical shell and scan a laser across its surface. For each incident ray, the object scatters a pattern of light onto the inner surface of the sphere, and we photograph the resulting radiance from the sphere's interior using a camera with a fisheye lens. Because of reciprocity, the image of the inside of the sphere corresponds to the reflectance function of the surface point illuminated by the laser, that is, the color that point would appear to a camera along the laser ray when the object is lit from each direction on the surface of the sphere. The measured reflectance functions allow the object to be photorealistically rendered from the laser's viewpoint under arbitrary directional illumination conditions. Since each captured reflectance function is a high-resolution image, our data reproduces sharp specular reflections and self-shadowing more accurately than previous approaches. We demonstrate our technique by scanning objects with a wide range of reflectance properties and show accurate renderings of the objects under novel illumination conditions.



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