Representation of roughness is introduced and the rationality of applying thephysics-based model in RE is analyzed at first. Then the scattering theory of electromagnetic waveis simplified and deduced to a physics-bas...Representation of roughness is introduced and the rationality of applying thephysics-based model in RE is analyzed at first. Then the scattering theory of electromagnetic waveis simplified and deduced to a physics-based model according to the characteristics of the surfaceto be reconstructed in RE. At last, the intensity diagrams of reflected field distribution areprovided to prove the feasibility of the presented model and some spheres are rendered with thismodel.展开更多
A fast algorithm for ray tracing is presented, with which the specular reflection term of global illumination model is improved. A hybrid technique combining hierarchical bounding volumes and constant size box partiti...A fast algorithm for ray tracing is presented, with which the specular reflection term of global illumination model is improved. A hybrid technique combining hierarchical bounding volumes and constant size box partitioning is presented and a fast box traversal algorithm is used. By this technique multiple ray intersections with objects that are in more than one box can be avoided. As a result, the speed of ray tracing is considerably increased.展开更多
Differences in illumination of the same face can defeat simple face recognition systems,yet most methods that compensate are too difficult to implement. Local quotient image (LQI) is an efficient illumination preproce...Differences in illumination of the same face can defeat simple face recognition systems,yet most methods that compensate are too difficult to implement. Local quotient image (LQI) is an efficient illumination preprocessing method for face recognition systems. An illumination model and a face model were developed,and their use in the new method was analyzed. Analysis of the method's computational complexity showed it to be efficient. Experimental results on Yale Face Database B showed that the method can effectively eliminate the effects of differences in illumination and provides considerable improvement in recognition rates.展开更多
A method has been proposed to model the illumination characteristics of a typical wire bonder vision system. The proposed model can be used to calibrate the illumination of the vision system to ensure the same level o...A method has been proposed to model the illumination characteristics of a typical wire bonder vision system. The proposed model can be used to calibrate the illumination of the vision system to ensure the same level of illumination brightness across different machines, given the same lighting level setting. The approach to extract the machine illumination model is semi-empirical and the model provides a closed-form solution.展开更多
Based on the equation of transfer in transport theory of optical physics,a new volume rendering model, called composed scattering model (CSM), is presented. In calculating the scattering term of the equation, it is de...Based on the equation of transfer in transport theory of optical physics,a new volume rendering model, called composed scattering model (CSM), is presented. In calculating the scattering term of the equation, it is decomposed into volume scattering intensity and surface scattering intensity, and they are composed with the boundary detection operator as the weight function. This proposed model differs from the most current volume rendering models in the aspect that in CSM segmentation and illumination intensity calculation are taken as two coherent parts while in ekisting models they are regarded as two separate ones. This model has been applied to the direct volume rendering of 3D data sets obtained by CT and MRI. The resultant images show not only rich details but also clear boundary surfaces. CSM is demonstrated to be an accurate volume rendering model suitable for CT and MRI data sets.展开更多
文摘Representation of roughness is introduced and the rationality of applying thephysics-based model in RE is analyzed at first. Then the scattering theory of electromagnetic waveis simplified and deduced to a physics-based model according to the characteristics of the surfaceto be reconstructed in RE. At last, the intensity diagrams of reflected field distribution areprovided to prove the feasibility of the presented model and some spheres are rendered with thismodel.
文摘A fast algorithm for ray tracing is presented, with which the specular reflection term of global illumination model is improved. A hybrid technique combining hierarchical bounding volumes and constant size box partitioning is presented and a fast box traversal algorithm is used. By this technique multiple ray intersections with objects that are in more than one box can be avoided. As a result, the speed of ray tracing is considerably increased.
文摘Differences in illumination of the same face can defeat simple face recognition systems,yet most methods that compensate are too difficult to implement. Local quotient image (LQI) is an efficient illumination preprocessing method for face recognition systems. An illumination model and a face model were developed,and their use in the new method was analyzed. Analysis of the method's computational complexity showed it to be efficient. Experimental results on Yale Face Database B showed that the method can effectively eliminate the effects of differences in illumination and provides considerable improvement in recognition rates.
文摘A method has been proposed to model the illumination characteristics of a typical wire bonder vision system. The proposed model can be used to calibrate the illumination of the vision system to ensure the same level of illumination brightness across different machines, given the same lighting level setting. The approach to extract the machine illumination model is semi-empirical and the model provides a closed-form solution.
文摘Based on the equation of transfer in transport theory of optical physics,a new volume rendering model, called composed scattering model (CSM), is presented. In calculating the scattering term of the equation, it is decomposed into volume scattering intensity and surface scattering intensity, and they are composed with the boundary detection operator as the weight function. This proposed model differs from the most current volume rendering models in the aspect that in CSM segmentation and illumination intensity calculation are taken as two coherent parts while in ekisting models they are regarded as two separate ones. This model has been applied to the direct volume rendering of 3D data sets obtained by CT and MRI. The resultant images show not only rich details but also clear boundary surfaces. CSM is demonstrated to be an accurate volume rendering model suitable for CT and MRI data sets.
