Mr. Yuanfa Cai Profile

Yuanfa Cai

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Publications (4)

Proceedings Article | 20 August 2013 Paper

A real-time autostereoscopic display method based on partial sub-pixel by general GPU processing

Duo Chen, Xinzhu Sang, Yuanfa Cai

Proceedings Volume 8913, 89130G (2013) https://doi.org/10.1117/12.2033041

KEYWORDS: Autostereoscopic displays, 3D displays, Graphics processing units, Binary data, Visualization, 3D image processing, Parallel computing, LCDs, Displays, OpenGL

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Proceedings Article | 20 August 2013 Paper

Reconstruction of 3D scenes from sequences of images

Bei Niu, Xinzhu Sang, Duo Chen, Yuanfa Cai

Proceedings Volume 8913, 89130H (2013) https://doi.org/10.1117/12.2033043

KEYWORDS: 3D modeling, Cameras, Clouds, Visual process modeling, Calibration, Reverse modeling, Systems modeling, Imaging systems, 3D image processing, Machine vision

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Reconstruction of three-dimensional (3D) scenes is an active research topic in the field of computer vision and 3D display. It’s a challenge to model 3D objects rapidly and effectively. A 3D model can be extracted from multiple images. The system only requires a sequence of images taken with cameras without knowing the parameters of camera, which provide flexibility to a high degree. We focus on quickly merging point cloud of the object from depth map sequences. The whole system combines algorithms of different areas in computer vision, such as camera calibration, stereo correspondence, point cloud splicing and surface reconstruction. The procedure of 3D reconstruction is decomposed into a number of successive steps. Firstly, image sequences are received by the camera freely moving around the object. Secondly, the scene depth is obtained by a non-local stereo matching algorithm. The pairwise is realized with the Scale Invariant Feature Transform (SIFT) algorithm. An initial matching is then made for the first two images of the sequence. For the subsequent image that is processed with previous image, the point of interest corresponding to ones in previous images are refined or corrected. The vertical parallax between the images is eliminated. The next step is to calibrate camera, and intrinsic parameters and external parameters of the camera are calculated. Therefore, The relative position and orientation of camera are gotten. A sequence of depth maps are acquired by using a non-local cost aggregation method for stereo matching. Then point cloud sequence is achieved by the scene depths, which consists of point cloud model using the external parameters of camera and the point cloud sequence. The point cloud model is then approximated by a triangular wire-frame mesh to reduce geometric complexity and to tailor the model to the requirements of computer graphics visualization systems. Finally, the texture is mapped onto the wire-frame model, which can also be used for 3D display. According to the experimental results, we can reconstruct a 3D point cloud model more quickly and efficiently than other methods.

Proceedings Article | 20 August 2013 Paper

Real-time arbitrary view synthesis method for ultra-HD auto-stereoscopic display

Yuanfa Cai, Xinzhu Sang, Chen Duo, Tianqi Zhao, Xin Fan, Nan Guo, Xunbo Yu, Binbin Yan

Proceedings Volume 8913, 891309 (2013) https://doi.org/10.1117/12.2032607

KEYWORDS: 3D displays, 3D image processing, Image processing, Video, LCDs, Lenticular lenses, Video acceleration, OpenGL, Cameras, 3D vision

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Proceedings Article | 20 August 2013 Paper

High-immersion three-dimensional display of the numerical computer model

Shujun Xing, Xunbo Yu, Tianqi Zhao, Yuanfa Cai, Duo Chen, Zhidong Chen, Xinzhu Sang

Proceedings Volume 8913, 89130N (2013) https://doi.org/10.1117/12.2033160

KEYWORDS: 3D displays, Cameras, 3D modeling, Computer simulations, Computing systems, Systems modeling, Coded apertures, Imaging systems, 3D visualizations, Visualization

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High-immersion three-dimensional (3D) displays making them valuable tools for many applications, such as designing and constructing desired building houses, industrial architecture design, aeronautics, scientific research, entertainment, media advertisement, military areas and so on. However, most technologies provide 3D display in the front of screens which are in parallel with the walls, and the sense of immersion is decreased. To get the right multi-view stereo ground image, cameras’ photosensitive surface should be parallax to the public focus plane and the cameras’ optical axes should be offset to the center of public focus plane both atvertical direction and horizontal direction. It is very common to use virtual cameras, which is an ideal pinhole camera to display 3D model in computer system. We can use virtual cameras to simulate the shooting method of multi-view ground based stereo image. Here, two virtual shooting methods for ground based high-immersion 3D display are presented. The position of virtual camera is determined by the people's eye position in the real world. When the observer stand in the circumcircle of 3D ground display, offset perspective projection virtual cameras is used. If the observer stands out the circumcircle of 3D ground display, offset perspective projection virtual cameras and the orthogonal projection virtual cameras are adopted. In this paper, we mainly discussed the parameter setting of virtual cameras。The Near Clip Plane parameter setting is the main point in the first method, while the rotation angle of virtual cameras is the main point in the second method. In order to validate the results, we use the D3D and OpenGL to render scenes of different viewpoints and generate a stereoscopic image. A realistic visualization system for 3D models is constructed and demonstrated for viewing horizontally, which provides high-immersion 3D visualization. The displayed 3D scenes are compared with the real objects in the real world.

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