Interactive Projector Position Detection Using Shadow-Free Dual Illumination
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Solution Overview
Problem
Existing interactive projectors face challenges in accurately detecting the position of a pointing element due to the influence of shadows in images taken by cameras, which degrades the detection accuracy.
Innovation Solution
The method involves using two cameras and corresponding illumination sections positioned to avoid imaging shadows of the pointing element, allowing for the acquisition of images that do not substantially include the shadow, thereby improving detection accuracy by using infrared light and configuring the illumination sections as ambient or coaxial to the cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a camera images the pointing element with conventional illumination, then the operation surface is adequately lit, but the shadow of the pointing element is imaged along with the pointing element, degrading detection accuracy
Solution Approach 1:
The illumination function is segmented into two independent systems: a first illumination section that provides ambient illumination to light up the operation surface, and a second illumination section that provides coaxial illumination for imaging the pointing element without creating shadows. This segmentation allows each illumination section to be optimized for its specific function, resolving the contradiction between adequate lighting and shadow-free imaging.
Solution Approach 2:
The patent introduces an intermediary illumination approach by using the second illumination section positioned coaxially with the camera. This intermediary lighting system acts as a mediator between the need for illumination and the need to avoid shadows, providing just enough light for accurate imaging without creating the shadow problems caused by conventional ambient lighting.
2Measurement precision
If multiple illumination sections are added to eliminate shadows, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The first illumination section serves multiple functions: it illuminates the operation surface for both visual reference and for the camera to capture the pointing element. The second illumination section, while primarily for shadow-free imaging, also contributes to overall lighting. This multi-functionality reduces the need for additional separate components, managing device complexity while improving detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of detecting the pointing element's position by preventing false detection caused by shadows, allowing for precise input recognition on the operation surface.
Implementation Method 1
performing illumination with a first illumination section disposed so that a shadow of the pointing element on the operation surface is not substantially imaged by the first camera
Implementation Method 2
performing illumination with a second illumination section disposed so that the shadow of the pointing element on the operation surface is not substantially imaged by the second camera
Data Source
AI summary
The position detection method includes the steps of (a) obtaining a first taken image by imaging a pointing element with an operation surface as a background using a first camera while performing illumination with a first illumination section disposed so that a shadow of the pointing element on the operation surface is not substantially imaged by the first camera, (b) obtaining a second taken image by imaging the pointing element with the operation surface as a background using a second camera disposed at a different position from a position of the first camera while performing illumination with a second illumination section disposed so that the shadow of the pointing element on the operation surface is not substantially imaged by the second camera, and (c) detecting a position of the pointing element with respect to the operation surface using the first taken image and the second taken image.