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61.
62.
通过分析建筑物沉降监测数据的特点,采用了指数平滑和曲线拟合模型对建筑物沉降监测数据进行处理,实现了两种数据处理模型的建模过程,并用于建筑物沉降量的实际预测,验证了模型的可行性。 相似文献
63.
线形工程中GPS高程拟合方法的探讨 总被引:1,自引:1,他引:1
介绍了多项式曲线拟合法和三次样条拟合法用于GPS水准联测点按线状或带状布设的情况,并通过实例简要分析了其优缺点。 相似文献
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65.
在DCS输出的地籍图上,有许多由直线段和曲线段组成的地物符号,用传统方法处理难以取得理想的绘图效果。本文在分析DCS数据结构和属性码的基础上,提出了曲线部分按三次参数样条曲线逼近,讨论了直线段和曲线段的各种组合情况,并且通过正确地选择边值条件使二者之间.的连接比较符合实际。最后扼要分析了该类线段按虚线绘出时的处理方法。 相似文献
66.
提出了一种基于图像恢复技术的遥感图像压缩技术,在提高遥感图像压缩比的同时,使压缩后的重建图像质量达到准无损的技术要求。对SRTF、TM图像的试验结果表明,该技术是可行的。 相似文献
67.
高分辨率数据中云高度的差异性突显,特别是边缘处高度在云阴影识别和地表辐射估算等方面成为需要考虑的重要因素。热红外数据获取云高度分辨率较低、缺乏细部差异性特征,为解决这一问题,首先将对应的热红外和可见光数据进行特征点配准,再将基于热红外数据计算的云高度重采样至高分辨率,然后以基于欧式距离变换的围线搜索方法及距离加权将热红外云边缘高度匹配至对应的可见光图像,最后根据云阴影的相似度匹配方法确定真实云高度。结果表明,算法在遵循热红外云高信息分布变化规律的同时,可以得到较准确的高分辨率云边缘高度,一定程度上解决了热红外技术获取云高在分辨率上的局限,扩展了其在云高反演方面的作用。 相似文献
68.
As an important canopy structure indicator, leaf area index (LAI) proved to be of considerable implications for forest ecosystem and ecological studies, and efficient techniques for accurate LAI acquisitions have long been highlighted. Airborne light detection and ranging (LiDAR), often termed as airborne laser scanning (ALS), once was extensively investigated for this task but showed limited performance due to its low sampling density. Now, ALS systems exhibit more competing capacities such as high density and multi-return sampling, and hence, people began to ask the questions like—“can ALS now work better on the task of LAI prediction?” As a re-examination, this study investigated the feasibility of LAI retrievals at the individual tree level based on high density and multi-return ALS, by directly considering the vertical distributions of laser points lying within each tree crown instead of by proposing feature variables such as quantiles involving laser point distribution modes at the plot level. The examination was operated in the case of four tree species (i.e. Picea abies, Pinus sylvestris, Populus tremula and Quercus robur) in a mixed forest, with their LAI-related reference data collected by using static terrestrial laser scanning (TLS). In light of the differences between ALS- and TLS-based LAI characterizations, the methods of voxelization of 3D scattered laser points, effective LAI (LAIe) that does not distinguish branches from canopies and unified cumulative LAI (ucLAI) that is often used to characterize the vertical profiles of crown leaf area densities (LADs) was used; then, the relationships between the ALS- and TLS-derived LAIes were determined, and so did ucLAIs. Tests indicated that the tree-level LAIes for the four tree species can be estimated based on the used airborne LiDAR (R2 = 0.07, 0.26, 0.43 and 0.21, respectively) and their ucLAIs can also be derived. Overall, this study has validated the usage of the contemporary high density multi-return airborne LiDARs for LAIe and LAD profile retrievals at the individual tree level, and the contribution are of high potential for advancing forest ecosystem modeling and ecological understanding. 相似文献
69.
汶川地震中离震中较远地区的高层建筑的震害 总被引:1,自引:1,他引:1
汶川地震中,陕西省西安市和宝鸡市两地处于远震区。远震区高层建筑比多层建筑的震害重。这两地高层建筑的震害主要表现为砌体填充墙和隔墙普遍出现裂缝;房屋顶部附近防震缝两侧的装饰材料震损,部分混凝土构件被撞坏;楼梯间的填充墙普遍开裂等。主体结构中的混凝土梁、柱和剪力墙等承重构件一般没有可见裂缝,部分剪力墙洞口连梁及框架一剪力墙结构中的连梁出现剪切斜裂缝或弯曲裂缝。文中初步分析了震害原因,并提出了设计建议。 相似文献
70.
Light Detection and Ranging (LiDAR) waveforms are being increasingly used in many forest and urban applications, especially for ground feature classification. However, most studies relied on either discretizing waveforms to multiple returns or extracting shape metrics from waveforms. The direct use of the full waveform, which contains the most comprehensive and accurate information has been scarcely explored. We proposed to utilize the complete waveform to test its ability to differentiate between objects having distinct vertical structures using curve matching approaches. Two groups of curve matching approaches were developed by extending methods originally designed for pixel-based hyperspectral image classification and object-based high spatial image classification. The first group is based on measuring the curve similarity between an unknown waveform and a reference waveform, including curve root sum squared differential area (CRSSDA), curve angle mapper (CAM), and Kullback–Leibler (KL) divergence. The second group assesses the curve similarity between an unknown and reference cumulative distribution functions (CDFs) of their waveforms, including cumulative curve root sum squared differential area (CCRSSDA), cumulative curve angle mapper (CCAM), and Kolmogorov–Smirnov (KS) distance. When employed to classify open space, trees, and buildings using ICESat waveform data, KL provided the highest average classification accuracy (87%), closely followed by CCRSSDA and CCAM, and they all significantly outperformed KS, CRSSDA, and CAM based on 15 randomized sample sets. 相似文献