A structured-light system with a binary defocusing technique has the potential to have more extensive application due to its high speeds, gamma-calibration-free nature, and lack of rigid synchronization requirements between the camera and projector. However, the existing calibration methods fail to achieve high accuracy for a structured-light system with an out-of-focus projector. This paper proposes a method that can accurately calibrate a structured-light system even when the projector is not in focus, making it possible for high-accuracy and high-speed measurement with the binary defocusing method. Experiments demonstrate that our calibration approach performs consistently under different defocusing degrees, and a root-mean-square error of about 73 μm can be achieved with a calibration volume of 150(H) mm×250(W) mm×200(D)mm.
With recent advancements in 3-D imaging and computational technologies, acquiring 3-D data is unprecedentedly simple. However, the use of 3-D data is still limited due to the size of 3-D data, especially 3-D video data. Therefore, the study of how to store and transmit the 3-D data in real time is vital. We address a technique that encodes a 3-D surface shape into a single 24-bit color image. In particular, this image is generated by advanced computer graphics tools with two primary color channels encoded as sine and cosine fringe images, and the third channel encoded as a stair image to unwrap the phase obtained from the two fringe images. An arbitrary 3-D shape can then be recovered from a single image. We test 3-D shapes with differing levels of complexity along with various image formats. Experiments demonstrate that, without significantly losing the shape quality, the compression ratio can go up to 1:36.86, compared with the native smallest possible 3-D data representation method. RightsCopyright 2010 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Abstract. With recent advancements in 3-D imaging and computational technologies, acquiring 3-D data is unprecedentedly simple. However, the use of 3-D data is still limited due to the size of 3-D data, especially 3-D video data. Therefore, the study of how to store and transmit the 3-D data in real time is vital. We address a technique that encodes a 3-D surface shape into a single 24-bit color image. In particular, this image is generated by advanced computer graphics tools with two primary color channels encoded as sine and cosine fringe images, and the third channel encoded as a stair image to unwrap the phase obtained from the two fringe images. An arbitrary 3-D shape can then be recovered from a single image. We test 3-D shapes with differing levels of complexity along with various image formats. Experiments demonstrate that, without significantly losing the shape quality, the compression ratio can go up to 1:36.86, compared with the native smallest possible 3-D data representation method.
A three-dimensional (3-D) shape measurement system that can simultaneously achieve 3-D shape acquisition, reconstruction, and display at 30 frames per second (fps) with 480,000 measurement points per frame is presented. The entire processing pipeline was realized on a graphics processing unit (GPU) without the need of substantial central processing unit (CPU) power, making it achievable on a portable device, namely a laptop computer. Furthermore, the system is extremely inexpensive compared with similar state-of-art systems, making it possible to be accessed by the general public. Specifically, advanced GPU techniques such as multipass rendering and offscreen rendering were used in conjunction with direct memory access to achieve the aforementioned performance. The developed system, implementation details, and experimental results to verify the performance of the proposed technique are presented. Disciplines Computer-Aided Engineering and Design | Mechanical Engineering Comments
Real-time 3D imaging is becoming increasingly important in areas such as medical science, entertainment, homeland security, and manufacturing. Numerous 3D imaging techniques have been developed, but only a few of them have the potential to achieve realtime. Of these few, fringe analysis based techniques stand out, having many advantages over the rest. This paper will explain the principles behind fringe analysis based techniques, and will provide experimental results from systems using these techniques.
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