针对以往稀疏编码在图像去噪过程中存在的噪声残留和缺乏对图像的边缘与细节的本质特征的保护等问题,提出了一种结合第二代Bandelet变换分块的字典学习图像去噪算法,其更好地利用了图像的几何特性进行去噪。首先,通过第二代Bandelet变...针对以往稀疏编码在图像去噪过程中存在的噪声残留和缺乏对图像的边缘与细节的本质特征的保护等问题,提出了一种结合第二代Bandelet变换分块的字典学习图像去噪算法,其更好地利用了图像的几何特性进行去噪。首先,通过第二代Bandelet变换可以灵活地根据图像几何流的正则性特征并能够自适应地获得图像的最稀疏表示来准确估计图像信息,并能自适应地选择最优的几何方向;然后,根据K-奇异值分解(K-Singular Value Decomposition,K-SVD)算法来训练学习字典;最后,通过四叉树分割对噪声图像进行自适应分块,从而去除噪声并保护图像的边缘与细节。实验结果表明,相比于其他学习字典,所提算法能更有效地保留图像的边缘特征与图像的精细结构。展开更多
Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of eleva...Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of elevation is introduced to express the undulation of topography.Then the coefficient is used to construct a node evaluation function in the terrain data model simplification step.Furthermore,an edge reduction strategy is combined with the improved restrictive quadtree segmentation to handle the crack problem.The experiment results demonstrated that the proposed method can reduce the amount of rendering triangles and enhance the rendering speed on the premise of ensuring the rendering effect compared with a traditional LOD algorithm.展开更多
文摘针对以往稀疏编码在图像去噪过程中存在的噪声残留和缺乏对图像的边缘与细节的本质特征的保护等问题,提出了一种结合第二代Bandelet变换分块的字典学习图像去噪算法,其更好地利用了图像的几何特性进行去噪。首先,通过第二代Bandelet变换可以灵活地根据图像几何流的正则性特征并能够自适应地获得图像的最稀疏表示来准确估计图像信息,并能自适应地选择最优的几何方向;然后,根据K-奇异值分解(K-Singular Value Decomposition,K-SVD)算法来训练学习字典;最后,通过四叉树分割对噪声图像进行自适应分块,从而去除噪声并保护图像的边缘与细节。实验结果表明,相比于其他学习字典,所提算法能更有效地保留图像的边缘特征与图像的精细结构。
基金Supported by the National Natural Science Foundation of China(61363075)the National High Technology Research and Development Program of China(863 Program)(2012AA12A308)the Yue Qi Young Scholars Program of China University of Mining&Technology,Beijing(800015Z1117)
文摘Aiming to deal with the difficult issues of terrain data model simplification and crack disposal,the paper proposed an improved level of detail(LOD)terrain rendering algorithm,in which a variation coefficient of elevation is introduced to express the undulation of topography.Then the coefficient is used to construct a node evaluation function in the terrain data model simplification step.Furthermore,an edge reduction strategy is combined with the improved restrictive quadtree segmentation to handle the crack problem.The experiment results demonstrated that the proposed method can reduce the amount of rendering triangles and enhance the rendering speed on the premise of ensuring the rendering effect compared with a traditional LOD algorithm.
