State Key Laboratory of Fundamental Science on Synthetic Vision

Chengdu, China

State Key Laboratory of Fundamental Science on Synthetic Vision

Chengdu, China
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Guo D.,Chinese Research Institute of Highway | Wang Q.,State Key Laboratory of Fundamental Science on Synthetic Vision
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

When investigating the scattering intensity distribution produced by a glass bead which is illuminated by a collimated beam with single length, Debye theory can be used to simulate and discuss the scattering properties. It is found that the intensity distribution of the k-order rainbow recorded by a detector which is on the left of a spherical particle is the superposition of the diffracted rays, the external reflected rays and the k time internal reflected rays primarily. The intensity distribution of the k-order rainbow on the right of the spherical particle is the superposition of the diffracted rays, the transmitting rays and the k time internal reflected rays mostly. When the wavelength of incident light is constant, the refractive index of the glass beads will change the degrees of the minimum deviation angle in the scattered light intensity distribution on the detector, and their diameters have no effect on the position of minimum deviation angle. Experimentally, the scattered intensity distribution of the first and the second rainbows of the glass beads with different refractive indices and radius are analyzed, and are compared with the geometrical method, which agrees with the result of simulation in Debye theory. This result shows that the proposed assumptions are reasonable, which can be used to measure the refractive index of the glass beads through testing the minimum deviation angle formed by the light scattering.


Sang G.,Sichuan University | Sang G.,State Key Laboratory of Fundamental Science on Synthetic Vision | Cai Y.,Sichuan University | Cai Y.,State Key Laboratory of Fundamental Science on Synthetic Vision | And 3 more authors.
Proceedings of the 2013 6th International Congress on Image and Signal Processing, CISP 2013 | Year: 2013

In this paper, a new fractional Fourier transform-based image fusion method is proposed. All the source images are decomposed by fractional Fourier transform, and then the fractional order are select adaptively. It has well solved the poor adaptability of previous image fusion methods. The experiments show that this algorithm is particularly effective not only on the general images fusion, but also have a good effect for the infrared and visible images fusion. © 2013 IEEE.


Liu C.,Sichuan University | Liu C.,State Key Laboratory of Fundamental Science on Synthetic Vision | Liu C.,Panzhihua University | Xiu-Qiong Z.,Sichuan University | And 3 more authors.
Lecture Notes in Electrical Engineering | Year: 2012

In this paper, we present a novel algorithm for fuzzy segmentation of infrared image data using fuzzy clustering. A conventional FCM assigns the data into group, where the data is nearest to the center of group. Although FCM is populated in image segmentation, it still has the following disadvantages: (1) a conventional FCM algorithm does not consider spatial information for clustering. (2) The algorithm is sensitive to noise. In this paper we present a fuzzy-means algorithm that incorporates spatial information and the prior probability of a pixel neighborhood into the membership function for clustering. The modified FCM has a great improvement for noisy image and infrared image segmentation. © 2012 Springer Science+Business Media B.V.


Lui C.,Sichuan University | Lui C.,State Key Laboratory of Fundamental Science on Synthetic Vision | Lui C.,Panzhihua University | Zhang X.,Sichuan University | And 7 more authors.
Journal of Computers | Year: 2012

FCM is used for image segmentation in some applications. It is based on a specific distance norm and does not use spatial information of the image, so it has some drawbacks. Various kinds of improvements have been developed to extend the adaptability, such as BFCM, SFCM and KFCM. These methods extend FCM from two aspects, one is replacing the Euclidean norm, and the other is considering the spatial information constraints for clustering. Kernel distance can improve the robustness for multi-distribution data sets. Spatial information can help eliminate the sensitivity to noises and outliers. In this paper, Gaussian kernel-based fuzzy c-means algorithm with spatial information (KSFCM) is proposed. KSFCM is more robust and adaptive. The experiment results show that KSFCM has the better performance. © 2012 ACADEMY PUBLISHER.


Li M.,University of Sichuan | Li D.,University of Sichuan | Zhang C.,University of Sichuan | E K.,University of Sichuan | And 3 more authors.
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2015

We present a modal wavefront reconstruction from slope measurements for rectangular optical components of high-power laser systems. Wavefront reconstruction with slope data is an important approach used for wavefront control or correction in high-power systems. In this work, we derive a complete set of orthonormal wavefront slope polynomials for rectangular apertures and describe the modal method for obtaining wavefront representation with the aberration balancing property. Error propagation properties for the modal method are evaluated and compared with the Southwell method. The cross-coupling error is also discussed. Numerical experiments are conducted to illustrate that the modal method can achieve a higher accuracy than the Southwell method. In addition, we also investigate the influence of noise on the modal method compared with that of the Southwell method. © 2015 Optical Society of America.


Li M.,University of Sichuan | Li D.,University of Sichuan | Wang Q.,University of Sichuan | Wang Q.,State Key Laboratory of Fundamental Science on Synthetic Vision | And 3 more authors.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2012

An orthonormal square Zernike basis set is generated from circular Zernike polynomial apodized square mask by use of the linearly independent set Gram-Schmidt orthogonalization technique. Based on the concepts of inner product, Euclidean space and norm in the linear algebra, a standard Zernike polynomial set is made orthogonal and a new orthonormal basis of polynomials named Z-square polynomial is established. Wavefront data in square aperture can be fitted with our new orthonormal set. It can not only fit the wavefront data with Z-square basis set itself, but also can be linearly composed of standard Zernike basis set by linear reverse transform and endows the decomposed wavefront modes with a correspondent aberration meaning. The experimental results show that the Z-square polynomial set can fit the wavefront aberration data in lens design efficiently and can also fit the practical wavefront phase data of Hartmann-Shack wavefront sensor testing, it provides a method of wavefront data analysis.


Li D.-H.,University of Sichuan | Qi X.-P.,University of Sichuan | Wang Q.-H.,University of Sichuan | Wang Q.-H.,State Key Laboratory of Fundamental Science on Synthetic Vision | And 3 more authors.
Optics Letters | Year: 2010

We propose a mathematic formula that can be applied to work out the amplitude distribution of a tested laser beam from its radial-shearing interferogram accurately, even if the amplitude distribution is extremely uneven. Provided that the background irradiance distribution of a tested beam is extracted from its cyclic radial-shearing (CRS) interferogram first, then using the radial-shearing ratio of the CRS interferometer, the amount of lateral shear along the orthogonal directions and the irradiance ratio, the amplitude distribution of a tested beam can be reconstructed accurately by the proposed formula. The simulation computation and experimental results show that the formula allows any amount of lateral shear to happen, as long as the contracted beam maintains its location inside its corresponding expanded version. © 2010 Optical Society of America.


E K.,University of Sichuan | Li D.,University of Sichuan | Li M.,University of Sichuan | Zhao J.,University of Sichuan | And 5 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2014

Measurement of planar element using slope sensor method is based on the geometry of the fringe reflection and phase measuring deflectometry method which can be used to measure aspherical shapes and transmission optical element rapidly, simply and accurately. It can be called deflectometry or Hartmann test system in reverse. We go through the derivation of measurement equation of planar element slope and wavefront reconstruction algorithm. By using an LCD screen with programmable fringe as illumination source, phase shifting method of four step is used to recognize display pixel coordinates, and a camera with small aperture images the surface under test. We apply this system to the measurement of acrylic plastic plate surface under the condition of and heating. The slope data can be obtained after operating these pictures by computer, and we use orthonormal vector polynomials fitting in a square area to calculate the surface shape of mirror under test, then analyze the surface information. And we use this system to test the slope change of acrylic plastic plate surface under the condition of stressing, and compare with the result of the laser-reflection method. The results show that the test system has a large dynamic range and is simple, rapid, non-contacting, and high-precision. It can supply a new method to test the planar surface shape and the dynamic changes of the object surface shape in practical production and application.


Zhang C.,University of Sichuan | Liu C.,University of Sichuan | Li D.,University of Sichuan | Li M.,University of Sichuan | And 2 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2013

Radial shearing interferometry has been widely used to test distorted wavefront. However, the result of wavefront measurement by using this technique includes two parts, one is the real phase information of wavefront under test and the other is the system errors in radial shearing interferometer. A calibration method of a radial shearing interferometer is presented. First of all, several fringe patterns of the phase difference distribution are obtained by a tested component with different positions. Then, the maximum likelihood method is used to combine the phase difference data and create a maximum likelihood function. After that, the wavefront under test and system errors can be separated. The simulation results show that the maximum likelihood method can deal with the issue of the calibration of a radial shearing interferometer. Furthermore, the method is used to reduce the effect of the system errors on extracting and reconstructing the wavefront under test.


Yuan H.-Z.,University of Sichuan | Yuan H.-Z.,State Key Laboratory of Fundamental Science on Synthetic Vision | Yuan H.-Z.,Anyang Teachers College | Wang B.-P.,University of Sichuan | And 4 more authors.
2010 International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2010 | Year: 2010

This paper describes a novel method based on selfadaptive subdivision mesh for geometry correction of multicameras in a panoramic video system. The system hardware consists of an array of six board cameras pointing outwardly. Digitally combining synchronized frames from each camera, a wide-field panoramic video can be created. Using sparse initial corresponding points between the ideal target surface and camera image, the proposed method can subdivide the grid into a dense one in arbitrary precision. Hence, the bijection between camera image and projection surface can be established in pixel level. This mapping can be used to warp a camera image to ideal panorama surface. The method is robust to lens distortion and camera relative position, and can seamlessly integrate with image matting processing. With the GPU processing, the real time frame rate panoramic video can be available. The experiment proves the effectiveness and simpleness of the method. © 2010 IEEE.

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