利用地面激光扫描数据进行建筑物变化检测     

吕钊  康志忠 《武汉大学学报(信息科学版)》2011,36(11)

利用地面激光扫描仪具有的数据获取速度快、精度高、实时性强、能全天候工作等优点,在快速获取三维点云的基础上,通过点云自动拼接、Hausdorff距离检测不同时期建筑物的三维模型变化,并改进了检测算法,提高了算法的执行效率。通过拟合平面构建Delaunay三角网求解变化区域的面积来评估灾害对建筑物的破坏程度,从而为灾害应急响应以及保险理赔等提供了可靠的决策依据。  相似文献   

电子海图最短距离航线自动生成的改进方法   总被引：1，自引：0，他引：1  

曹鸿博  张立华  贾帅东  张莉 《武汉大学学报(信息科学版)》2011,36(9):1107-1110

针对航路二叉树方法绕行碍航区处理不完备、效率低等缺点,提出了最短距离航线自动生成的改进方法。通过复杂碍航区路径的递归搜索和碍航区绕行规则的优化,实现了复杂情形下的航线自动生成;利用方向一致性判断、边界检测和动态包络矩形排斥等策略优化航线生成,并采用递归处理和动态判断的方式求解最短距离航线。此方法与已有的航路二叉树方法相比,在自动生成航线的质量和效率上都有明显提高。  相似文献   

利用DEM边缘检测进行黄土地貌沟沿线自动提取   总被引：6，自引：0，他引：6  

晏实江  汤国安  李发源  董有福 《武汉大学学报(信息科学版)》2011,(3):363-367

在分析黄土地貌沟沿线形态特征的基础上,提出了基于规则格网DEM,通过引入边缘检测算子提取并连接沟沿线候选点,并借助形态学方法滤除细碎线段,最终生成沟沿线的方法。黄土丘陵沟壑区的实验结果显示,Sobel、Roberts、Prewitt梯度算子检测得到的沟沿线封闭性较差,线段较零碎,与实际沟沿线不符,不适用于沟沿线的自动提取;而LOG算子提取的线段连续、精度高,是理想的沟沿线检测算子,能够实现黄土地貌沟沿线较准确、有效的自动提取。  相似文献   

GNSS实时数据质量控制   总被引：2，自引：2，他引：0  

蔡华  赵齐乐  孙汉荣  胡志刚 《武汉大学学报(信息科学版)》2011,(7):820-824

设计了一套实时数据质量控制模块,利用观测值的多种线性组合进行周跳探测及修复,并对观测方程的验后残差进行实时分析,来探测粗差和周跳,从而使实时数据的处理结果更加稳定可靠,并在PANDA单历元实时数据处理模块(SRIF)的基础上,运用实时质量控制模块进行试验。结果表明,此模块更加稳定可靠,适用于GNSS实时数据处理。  相似文献   

遥感自动提取海岸线方法   总被引：1，自引：0，他引：1  

丁亚杰 《地理空间信息》2011,(4):37-39

利用遥感技术确定海岸线位置的问题受到关注由来已久,就其在国内外的研究现状做了介绍,利用小波边缘检测算子提取出黄河三角洲河口区2004年Landsat TM图像的海岸线位置;在分析小波算子与传统边缘提取方法相比的优点的同时,并就其存在的不足提出了今后的研究重点。  相似文献   

基于验后方差估计原理导出的选权迭代法剔除粗差     

孙同贺 《测绘与空间地理信息》2011,34(1):215-217

将抗差估计的思想融入到粗差探测的算法中,设计出对模型误差,特别是粗差具有抵抗能力的粗差探测算法.基于验后方差估计原理导出的选权迭代法即为抗差佑计的一种,首先是应用最小二乘法来计算观测值的参数x、残差V、协因数阵Qvv及单位权σ0 的初值,然后再根据残差和有关的参数,按所选择的权函数,计算每个观测值的权,经过迭代计算求得...  相似文献   

基于航空LIDAR点云数据提取城市地区建筑物的目标     

李福金  秦志伟 《测绘与空间地理信息》2011,34(3):187-190

以航空LIDAR点云数据为基础,在无其他辅助数据的情况下,采用数字图像处理技术,实现基于航空LIDAR点云数据提取城市地区建筑物的目标.  相似文献   

最优小波尺度空间的图像边缘检测方法     

胡凯  张颖超  钱蕾 《南京气象学院学报》2011,(3):259-264

根据图像和检测算子的特性,以相关性为准则,使用遗传算法对图像小波变换的尺度进行选择,从而构成一种自适应的高斯小波尺度空间.融合该空间下不同尺度检测的图像边缘,使得整幅图像的边缘细节丰富清晰,具有更好的抗噪性能.对测试图像使用Canny算法、单尺度、二进尺度和自适应尺度小波进行边缘检测,验证了该算法在去除噪声和准确定位方面的有效性.  相似文献   

基于合成孔径雷达交叉极化通道数据的海上目标探测   总被引：1，自引：0，他引：1  

王运华  刘晓燕  李慧敏  张彦敏 《海洋学报(英文版)》2015,34(1):85-93

Azimuth ambiguities(ghost targets) discrimination is of great interest with the development of a synthetic aperture radar(SAR). And the azimuth ambiguities are often mistaken as actual targets and cause false alarms. For actual targets, HV channel signals acquired by a fully polarimetric SAR are approximately equal to a VH channel in magnitude and phase, i.e., the reciprocity theorem applies, but shifted in phase about ± for the first-order azimuth ambiguities. Exploiting this physical behavior, the real part of the product of the two cross-polarized channels, i.e.(S S)HV VH, hereafter called A12 r, is employed as a new parameter for a target detection at sea. Compared with other parameters, the contrast of A12 r image between a target and the surrounding sea surface will be obviously increased when A12 r image is processed by mean filtering algorithm. Here, in order to detect target with constant false-alarm rates(CFARs), an analytical expression for the probability density function(pdf) of A12 r is derived based on the complex Wishart-distribution. Because a value of A12 r is greater/less than 0 for real target/its azimuth ambiguities, the first-order azimuth ambiguities can be completely removed by this A12r-based CFAR technology. Experiments accomplished over C-band RADARSAT-2 fully polarimetric imageries confirm the validity.  相似文献   

Dose of truth—Monitoring marine non-indigenous species to serve legislative requirements     

《Marine Policy》2015

Non-indigenous species (NIS) are recognized as a global threat to biodiversity and monitoring their presence and impacts is considered a prerequisite for marine environmental management and sustainable development. However, monitoring for NIS seldom takes place except for a few baseline surveys. With the goal of serving the requirements of the EU Marine Strategy Framework Directive and the EU Regulation on the prevention and management of the introduction and spread of invasive alien species, the paper highlights the importance of early detection of NIS in dispersal hubs for a rapid management response, and of long-term monitoring for tracking the effects of NIS within recipient ecosystems, including coastal systems especially vulnerable to introductions. The conceptual framework also demonstrates the need for port monitoring, which should serve the above mentioned requirements but also provide the required information for implementation of the International Convention for the Control and Management of Ships Ballast Water and Sediments. Large scale monitoring of native, cryptogenic and NIS in natural and man-made habitats will collectively lead to meeting international requirements. Cost-efficient rapid assessments of target species may provide timely information for managers and policy-advisers focusing on particular NIS at particular localities, but this cannot replace long-term monitoring. To support legislative requirements, collected data should be verified and stored in a publicly accessible and routinely updated database/information system. Public involvement should be encouraged as part of monitoring programs where feasible.  相似文献