Fiber Optic Projector Calibration
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In many projector-based systems, it is necessary to align the projection with the surface being projected upon. We automate this task via light sensors embedded in the projection surface.
Background & Objective: MERL has done a large number of projects involving precision computer video projection. Examples include DiamondTouch, Shader Lamps, Interactive Retail Displays, etc. In all of these cases, the projection must be accurately aligned to the surface. In the past, we have used semi-automated procedures where a user must indicate certain target locations, allowing the various geometries to be calculated and the projection suitably warped to match the surface. Unfortunately, this is a tedious process prone to human error. Our new system is fully automated and can quickly and precisely locate key pixel positions. Hopefully, this will greatly increase the practicality of our various projector-based systems.
Technical Discussion: The calibration system uses light sensors which are embedded underneath the projection surface. Binary Gray code patterns are projected onto the surface to discover the precise pixel location of each sensor. For an XGA display, only 20 patterns are required to create a unique sequence at each pixel. To simplify the system, inexpensive fiber optics are used to carry the light from the sensing points to a single detector board. Once the precise pixel locations are known, the projection can then be suitably aligned, either through image warping or mechanical adjustment.
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Technology Area: Off the Desktop Interaction and Display
Modification Date: July 7, 2008