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971.
LONG Hualou 《地理学报》2014,24(2):211-225
The implementation of new type industrialization and urbanization and agricultural modernization strategies lacks of a major hand grip and spatial supporting platform,due to long-term existed "dual-track" structure of rural-urban development in China as well as unstable rural development institution and mechanism. It is necessary to restructure rural production,living and ecological space by carrying out land consolidation,so as to establish a new platform for building new countryside and realizing urban-rural integration development in China. This paper develops the concept and connotation of rural spatial restructuring. Basing on the effects analysis of industrialization and urbanization on rural production,living and ecological space,the mechanism of pushing forward rural spatial restructuring by carrying out land consolidation is probed. A conceptualization of the models of rural production,living and ecological spatial restructuring is analyzed combining with agricultural land consolidation,hollowed villages consolidation and industrial and mining land consolidation. Finally,the author argues that a "bottom-up" restructuring strategy accompanied by a few "top-down" elements is helpful for smoothly pushing forward rural spatial restructuring in China. In addition,the optimization and restructuring of rural production,living and ecological space will rely on the innovations of regional engineering technology,policy and mechanism,and mode of rural land consolidation,and more attentions should be paid to rural space,the foundation base and platform for realizing urban-rural integration development. 相似文献
972.
Estimation of forest aboveground biomass (AGB) is informative of the role of forest ecosystems in local and global carbon budgets. There is a need to retrospectively estimate biomass in order to establish a historical baseline and enable reporting of change. In this research, we used temporal spectral trajectories to inform on forest successional development status in support of modelling and mapping of historic AGB for Mediterranean pines in central Spain. AGB generated with ground plot data from the Spanish National Forest Inventory (NFI), representing two collection periods (1990 and 2000), are linked with static and dynamic spectral data as captured by Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) sensors over a 25 year period (1984–2009). The importance of forest structural complexity on the relationship between AGB and spectral vegetation indices is revealed by the analysis of wavelet transforms. Two-dimensional (2D) wavelet transforms support the identification of spectral trajectory patterns of forest stands that in turn, are associated with traits of individual NFI plots, using a flexible algorithm sensitive to capturing time series similarity. Single-date spectral indices, temporal trajectories, and temporal derivatives associated with succession are used as input variables to non-parametric decision trees for modelling, estimation, and mapping of AGB and carbon sinks over the entire study area. Results indicate that patterns of change found in Normalized Difference Vegetation Index (NDVI) values are associated and relate well to classes of forest AGB. The Tasseled Cap Angle (TCA) index was found to be strongly related with forest density, although the related patterns of change had little relation with variability in historic AGB. By scaling biomass models through small (∼2.5 ha) spatial objects defined by spectral homogeneity, the AGB dynamics in the period 1990–2000 are mapped (70% accuracy when validated with plot values of change), revealing an increase of 18% in AGB irregularly distributed over 814 km2 of pines. The accumulation of C calculated in AGB was on average 0.65 t ha−1 y−1, equivalent to a fixation of 2.38 t ha−1 y−1 of carbon dioxide. 相似文献
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974.
介绍了极坐标放样法在任意点设站测设曲线中线桩的原理和方法,充分利用全站仪和可编程计算器的优点,可一次设站多次放样,该法具有测站选择灵活,测设速度快,放样点位精度高等优点,是一种很好的放样方法。 相似文献
975.
Meiling Liu Xiangnan Liu Weicui Ding Ling Wu 《International Journal of Applied Earth Observation and Geoinformation》2011
Remote sensing allows monitoring heavy metal pollution in crops for agricultural production and food security. This paper presents an approach to wavelet-fractal analysis for exploring a set of sensitive spectral parameters to monitor the heavy metal pollution levels in rice crops from hyperspectral reflectance data. Hyperspectral and biochemical data were collected from three study farms in Changchun, Jilin Province, China. Our study explored the fractal dimension of reflectance with wavelet transform (FDWT) that demonstrated a better performance than other existing methods. Our results obtained in this study show that the red edge position (REP) was the most sensitive indicator for monitoring the heavy metal pollution levels in rice crops among common indices. As compared with REP, the FDWT is more sensitive to biochemical composition, namely with respect to chlorophyll concentrations, N, Cu and Cd. The established linear models showed a correlation coefficient (R2) above 0.70, model efficiency (ME) above 0.65 and a root mean square error (RMSE) below 3.5. Minimum FDWT values occurred in rice with Level II pollution followed by Level I pollution, and finally the safe level. This study suggests that wavelet transform is well suited as a spectral analysis method to eliminate noise and amplify the stress information from heavy metals. The wavelet transform in conjunction with fractal analysis is promising for detecting heavy metal-induced stress in rice crops. 相似文献
976.
基于SIFT的宽基线立体影像密集匹配 总被引:2,自引:2,他引:0
提出基于对极几何和单应映射双重约束及SIFT特征的宽基线立体影像多阶段准密集匹配算法。算法包括三个阶段:①基于特征点的空间分布和信息熵选取一定数量的最优SIFT特征点集并进行最小二乘初始稀疏匹配及立体像对的基本矩阵和单应矩阵估计;②对于其余特征,利用同名核线倾斜角及SIFT特征的尺度信息对匹配窗口的仿射变换参数进行迭代优化及变形改正、提取仿射不变SIFT特征描述符,并基于双重约束信息及欧氏距离测度进行匹配;③考虑宽基线立体影像较低的特征提取重复率,对第②步左右影像中未能成功匹配的特征点,基于双向搜索策略,采用基于盒滤波加速计算的SSD测度在变形改正后的双重约束区域中进行匹配,并对匹配结果进行加权最小二乘拟合定位。实际的宽基线立体影像试验结果证明了算法的有效性,可为后续的三维重建提供较为可靠的密集或准密集匹配点。 相似文献
977.
978.
979.
坐标系统转换引起宗地面积变形分析 总被引:1,自引:1,他引:0
探讨了1954年北京坐标系和1980西安坐标系之间的转换方法.以实际项目为例,通过计算与分析,得出影响54、80坐标系统下面积变形的主要因素是坐标转换中的尺度因子. 相似文献
980.