针对最大互信息系数(maximal information coefficient,MIC)近似算法在大规模数据场景下的计算时间复杂度高,计算时间增长快的问题,提出一种最大互信息系数并行计算(parallel computing maximal information coefficient,PCMIC)方法。...针对最大互信息系数(maximal information coefficient,MIC)近似算法在大规模数据场景下的计算时间复杂度高,计算时间增长快的问题,提出一种最大互信息系数并行计算(parallel computing maximal information coefficient,PCMIC)方法。分别在Spark和Spark-MPI(message passing interface)计算框架中,在不同的数据规模和不同的噪声水平下,利用PCMIC算法对14种典型的相关关系做并行计算。另外在不同节点数的情况下,选择两种具有代表性的相关关系来测试PCMIC算法在两种计算框架中的性能。结果表明:PCMIC算法在两种框架下的运算效果与原始MIC近似算法相比,同样具有普适性和均匀性,而且具有良好的可扩展性;随着数据规模和节点数的增加,PCMIC算法在两种框架中运算的时间增长明显比MIC近似算法慢,而且在Spark-MPI框架下的并行加速比和效率略优于Spark;Spark能够支持MPI任务的调度,为研究不同并行计算框架之间的融合奠定了一定的理论和应用基础。展开更多
An improved image registration method is proposed based on mutual infor- mation with hybrid optimizer. Firstly, mutual information measure is combined with morphological gradient information. The essence of the gradie...An improved image registration method is proposed based on mutual infor- mation with hybrid optimizer. Firstly, mutual information measure is combined with morphological gradient information. The essence of the gradient information is that locations a large gradient magnitude should be aligned, but also the orientation of the gradients at those locations should be similar. Secondly, a hybrid optimizer combined PSO with Powell algorithm is proposed to restrain local maxima of mutual information function and improve the registration accuracy to sub-pixel level. Lastly, muhlresolution data structure based on Mallat decomposition can not only improve the behavior of registration function, but also improve the speed of the algorithm. Experimental results demonstrate that the new method can yield good registration result, superior to traditional optimizer with respect to smoothness and attraction basin as well as convergence speed.展开更多
Our study deals with two major issues impacting current WebGIS development： interoperability of heterogeneous data and visualization of vector data on the Web. By using the combination of Geography Markup Language （...Our study deals with two major issues impacting current WebGIS development： interoperability of heterogeneous data and visualization of vector data on the Web. By using the combination of Geography Markup Language （GML）, Scalable Vector Graphics （SVG） and Web Feature Service （WFS） Implementation Specifications developed by the OpenGIS Consortium （OGC）, a strategy of WebGIS is proposed. The GML is used as a coding and data transportation mechanism to realize interoperability, the SVG to display GML data on the Web and the WFS as a data query mechanism to access and retrieve data at the feature level in real time on the Web. A case study shows that the combination mentioned above has enormous potential to achieve interoperability while not requiring considerable changes to existing legacy data. Original data formats need not be changed and could still be retrieved using WFS and transformed into GML in real time. SVG can oroduce suoerior ouality vector maps on a Web browser.展开更多
文摘针对最大互信息系数(maximal information coefficient,MIC)近似算法在大规模数据场景下的计算时间复杂度高,计算时间增长快的问题,提出一种最大互信息系数并行计算(parallel computing maximal information coefficient,PCMIC)方法。分别在Spark和Spark-MPI(message passing interface)计算框架中,在不同的数据规模和不同的噪声水平下,利用PCMIC算法对14种典型的相关关系做并行计算。另外在不同节点数的情况下,选择两种具有代表性的相关关系来测试PCMIC算法在两种计算框架中的性能。结果表明:PCMIC算法在两种框架下的运算效果与原始MIC近似算法相比,同样具有普适性和均匀性,而且具有良好的可扩展性;随着数据规模和节点数的增加,PCMIC算法在两种框架中运算的时间增长明显比MIC近似算法慢,而且在Spark-MPI框架下的并行加速比和效率略优于Spark;Spark能够支持MPI任务的调度,为研究不同并行计算框架之间的融合奠定了一定的理论和应用基础。
文摘An improved image registration method is proposed based on mutual infor- mation with hybrid optimizer. Firstly, mutual information measure is combined with morphological gradient information. The essence of the gradient information is that locations a large gradient magnitude should be aligned, but also the orientation of the gradients at those locations should be similar. Secondly, a hybrid optimizer combined PSO with Powell algorithm is proposed to restrain local maxima of mutual information function and improve the registration accuracy to sub-pixel level. Lastly, muhlresolution data structure based on Mallat decomposition can not only improve the behavior of registration function, but also improve the speed of the algorithm. Experimental results demonstrate that the new method can yield good registration result, superior to traditional optimizer with respect to smoothness and attraction basin as well as convergence speed.
基金Project 2006A018 supported by the Youth Scientific Research Foundation of China University of Mining & Technology
文摘Our study deals with two major issues impacting current WebGIS development： interoperability of heterogeneous data and visualization of vector data on the Web. By using the combination of Geography Markup Language （GML）, Scalable Vector Graphics （SVG） and Web Feature Service （WFS） Implementation Specifications developed by the OpenGIS Consortium （OGC）, a strategy of WebGIS is proposed. The GML is used as a coding and data transportation mechanism to realize interoperability, the SVG to display GML data on the Web and the WFS as a data query mechanism to access and retrieve data at the feature level in real time on the Web. A case study shows that the combination mentioned above has enormous potential to achieve interoperability while not requiring considerable changes to existing legacy data. Original data formats need not be changed and could still be retrieved using WFS and transformed into GML in real time. SVG can oroduce suoerior ouality vector maps on a Web browser.
