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排序方式: 共有459条查询结果,搜索用时 160 毫秒
91.
《International Journal of Digital Earth》2013,6(6):639-655
ABSTRACTImage fusion techniques that blend multi-sensor characteristics to generate synthetic data with fine resolutions have generated great interest within the remote sensing community. Over the past decade, although many advances have been made in the spatiotemporal fusion models, there still remain several shortcomings in existing methods. In this article, a hierarchical spatiotemporal adaptive fusion model (HSTAFM) is proposed for producing daily synthetic fine-resolution fusions. The suggested model uses only one prior or posterior image pair, especially with the aim being to predict arbitrary temporal changes. The proposed model is implemented in two stages. First, the coarse-resolution image is enhanced through super-resolution based on sparse representation; second, a pre-selection of temporal change is performed. It then adopts a two-level strategy to select similar pixels, and blends multi-sensor features adaptively to generate the final synthetic data. The results of tests using both simulated and actual observed data show that the model can accurately capture both seasonal phenology change and land-cover-type change. Comparisons between HSTAFM and other developed models also demonstrate our proposed model produces consistently lower biases. 相似文献
92.
《The Cartographic journal》2013,50(1):12-21
Abstract<title/>Cartogram is a technique for visualisation of the geographical distribution of spatial data. It has two main types, i.e. distance cartogram and area cartogram. Area cartogram is a transformed map in which areas are resized in proportion to an attribute value. A number of techniques have been developed for the generation of area cartograms. Some researchers consider cartogram as a very effective technique for visualisation of spatial data, while others doubt about the effectiveness because of the possible distortion in shape and/or disconnectivity in topology. This study aims to evaluate the effectiveness of area cartogram for visualizing spatial data. In this study, two comparative experiments have been conducted. One is the comparison between thematic maps and cartograms, and the other is the comparison among different types of area cartogram. Two sets of data with different characteristics are used, i.e. 2005 China population data and 1996 US election data. Results show that cartogram is more effective in the representation of the 1996 US election data which provides a qualitative result (i.e. in binary form or nominal data), but thematic map is far more effective in the representation of 2005 China population data which provides a quantitative result (in classes or ordinal data). It is also found that among different types of area cartogram, pseudo-cartogram is the most preferred technique and Dorling cartogram is the least preferred one. 相似文献
93.
Scree Representation on Topographic Maps 总被引:1,自引:0,他引:1
none 《The Cartographic journal》2013,50(2):141-149
Abstract<title/>Scree patterns are an important element of mountain maps in Swiss style. The size and density of scree dots vary with the exposition towards a source of illumination, which makes the dots extremely labour intensive to map without specialized algorithms. This paper identifies design principles for the symbolisation of scree fields on mountain slopes and presents a digital method for the quick placement of dot symbols requiring only minimal interventions by a cartographer. When digitally produced scree is combined with a shaded relief and a rock drawing, the terrain appears as a continuous three-dimensional surface to the reader. The described method is implemented in Scree Painter, a specialized free open-source software application. Scree patterns produced with Scree Painter match the quality standards of manually generated scree representations. 相似文献
94.
Linear quadtree is a popular image representation method due to its convenient imaging procedure. However, the excessive emphasis on the symmetry of segmentation, i.e. dividing repeatedly a square into four equal sub-squares, makes linear quadtree not an optimal representation. In this paper, a no-loss image representation, referred to as Overlapped Rectangle Image Representation (ORIR), is presented to support fast image operations such as Legendre moments computation. The ORIR doesn’t importune the symmetry of segmentation, and it is capable of representing, by using an identical rectangle, the information of the pixels which are not even adjacent to each other in the sense of 4-neighbor and 8-neighbor. Hence, compared with the linear quadtree, the ORIR significantly reduces the number of rectangles required to represent an image. Based on the ORIR, an algorithm for exact Legendre moments computation is presented. The theoretical analysis and the experimental results show that the ORIR-based algorithm for exact Legendre moments computation is faster than the conventional exact algorithms. 相似文献
95.
This paper develops a wide-band multi-spectral space for color representation with Aitken PCA algorithm. This novel mathematical space using the broad-band spectra matching method aims at improving the accuracy of color representation as well as reducing costs for processing and storing multi-spectral images. The results show that the space can present our experimental original spectral spaces (i. e. Munsell color matt and DIN-6164 color chips) with high efficiency, and that the spanning space with three eigenvectors can present the original space at more than 98% CSCR, and when 5 eigenvectors are used it can cover almost the whole original spaces. 相似文献
96.
针对规划公示信息的多层次公众认知需求,利用本体思想解析土地利用规划信息,构建有向图为框架的信息重构模型;设计模型要素的关系数据结构,实现基于图遍历的信息检索与语义表达算法。以海南省昌江黎族自治县土地利用总体规划成果(2006~2020年)为实例,验证了模型的有效性。 相似文献
97.
ArcSDE压缩二进制是ArcSDE在关系型数据库(RDBMS)中保存地理信息中二进制几何图形的存储格式,这种格式采用将浮点几何数据整形化的方法进行数据压缩,减少了数据存储空间,同时也加快了数据在网络上传输的速度。本文通过对ArcSDE压缩二进制存储格式的研究与分析,指出了这种格式在存取和处理效率上的不足之处,并提出了更为高效的改进方法。 相似文献
98.
99.
100.
城市复杂道路网的Stroke生成方法 总被引:2,自引:0,他引:2
传统连接stroke的方法在处理表达较为详细的城市道路网数据时,会产生双行道分离和环岛处截断等错误.为能够在城市复杂道路网中正确生成stroke,针对道路网中的双行道和道路交叉口模式提出一种新的stroke生成方法.该方法采用道路街区几何形态分析、基于连通关系的层次聚类等算法自动识别出道路网中的双行道和道路交叉口模式,并使用穷举stroke配对组合算法连接截断的stroke,从而保证stroke的连续性.以武汉市NAVIN-FOTM导航电子地图数据为例验证该方法的实用性,生成的stroke符合stroke感知归组原则中平滑连贯的要求. 相似文献