The deformable screen is made from a thin, translucent elastic fabric (e.g. spandex-based fibers - better known as Lycra). There are several ways to "scan" this surface in order to extract its depth characteristics. A rather conventional technique would rely on a 2D scanning rangefinder. After giving the problem some though, I decided to study a cheaper technique not relying on any laser scanner. In fact, a a conventional CCD camera and a special illumination configuration will suffice: using an on-axis infrared source (such as a LED ring) and a conventional CCD camera (with an IR filter), it should be possible to acquire a gray-scale image indicating, at each location in the surface, the actual inclination between the illuminating ray and the surface-normal; if both the camera and the light source are relatively far from the screen, and placed so as to share the same optical axis (see figure), then it is relatively easy to compute the actual deformation of the screen from the gray-scale map data.To enhance infrared reflectivity and disminish the eventuallity of projector hot spots, the spandex-based fabric is plastic coated on the inner side.
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