GIS数字曲线复杂性的度量与误差建模中趋势项的分离

引入了衡量GIS数字曲线复杂性的四种指标,提出了误差建模中趋势项分离的样条函数法,考察了分离一组具有不同复杂度模拟曲线的有效性,并与差分法进行了比较。     

一种基于微博签到数据的城市功能区复合程度探究方法

城市功能区复合程度是城市发展规划、评价城市区域发展均衡性的重要参考.本文以深圳市为研究对象,首先,划分渔网单元与微博签到数据求交计算样方单元各类签到数据比例.其次,采用香农熵对复合程度进行定量化描述并连接渔网赋予属性值.最后,基于ArcGIS由粗至细进行可视化呈现和分析.结果表明,提出的方法能够有效地表示城市功能区的复...     

Fault architecture and deformation mechanisms in exhumed analogues of seismogenic carbonate-bearing thrusts

Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC′ tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of “aseismic” behaviour.     

Perceptual complexity of soil-landscape maps: a user evaluation of color organization in legend designs using eye tracking

ABSTRACT

We compared the ability of two legend designs on a soil-landscape map to efficiently and effectively support map reading tasks with the goal of better understanding how the design choices affect user performance. Developing such knowledge is essential to design effective interfaces for digital earth systems. One of the two legends contained an alphabetical ordering of categories, while the other used a perceptual grouping based on the Munsell color space. We tested the two legends for 4 tasks with 20 experts (in geography-related domains). We analyzed traditional usability metrics and participants’ eye movements to identify the possible reasons behind their success and failure in the experimental tasks. Surprisingly, an overwhelming majority of the participants failed to arrive at the correct responses for two of the four tasks, irrespective of the legend design. Furthermore, participants’ prior knowledge of soils and map interpretation abilities led to interesting performance differences between the two legend types. We discuss how participant background might have played a role in performance and why some tasks were particularly hard to solve despite participants’ relatively high levels of experience in map reading. Based on our observations, we caution soil cartographers to be aware of the perceptual complexity of soil-landscape maps.     

Linking landscape morphological complexity and sediment connectivity

Connectivity relates to the coupling of landforms (e.g. hillslopes and channels) and the transfer of water and sediment between them. The degree to which parts of a catchment are connected depends largely on the morphological complexity of the catchment's landscape. Landscapes can have very different and distinct morphologies, such as terraces, V‐shaped valleys or broad floodplains. The objective of this study is to better understand and quantify the relation between landscape complexity and catchment connectivity. We hypothesize that connectivity decreases with increasing landscape morphological complexity. To quantify the connectivity–complexity relationship virtual digital elevation models (DEMs) with distinct morphologies were used as inputs into the landscape evolution model LAPSUS to simulate the sediment connectivity of each landscape. Additionally, the hypothesis was tested on six common real DEMs with widely different morphologies. Finally, the effects of different rainfall time series on catchment response were explored. Simulation results confirm the hypothesis and quantify the non‐linear relation. Results from the exploration of sediment connectivity in response to sequences of rainfall events indicate that feedback between erosion and deposition are more important for certain landscape morphologies than for others: for a given rainfall input, a more effective sediment connectivity and erosion response may be expected from rolling or V‐shaped catchments than from dissected or stepped landscapes. Awareness of the differences in the behaviour and response of different morphologies to catchment processes provides valuable information for the effective management of landscapes and ecosystems through efficiently designed soil and water conservation measures. Copyright © 2013 John Wiley & Sons, Ltd.     

Computational complexity of spatial reasoning with directional relationship

The property of NP-completeness of topologic spatial reasoning problem has been proved. According to the similarity of uncertainty with topologic spatial reasoning, the problem of directional spatial reasoning should be also an NP-complete problem. The proof for the property of NP-completeness in directional spatial reasoning problem is based on two important transformations. After these transformations, a spatial configuration has been constructed based on directional constraints, and the property of NP-completeness in directional spatial reasoning has been proved with the help of the consistency of the constraints in the configuration.     

Wholeness as a hierarchical graph to capture the nature of space

According to Christopher Alexander’s theory of centers, a whole comprises numerous, recursively defined centers for things or spaces surrounding us. Wholeness is a type of global structure or life-giving order emerging from the whole as a field of the centers. The wholeness is an essential part of any complex system and exists, to some degree or other, in spaces. This paper defines wholeness as a hierarchical graph, in which individual centers are represented as the nodes and their relationships as the directed links. The hierarchical graph gets its name from the inherent scaling hierarchy revealed by the head/tail breaks, which is a classification scheme and visualization tool for data with a heavy-tailed distribution. We suggest that (1) the degrees of wholeness for individual centers should be measured by PageRank (PR) scores based on the notion that high-degree-of-life centers are those to which many high-degree-of-life centers point, and (2) that the hierarchical levels, or the ht-index of the PR scores induced by the head/tail breaks, can characterize the degree of wholeness for the whole: the higher the ht-index, the more life or wholeness in the whole. Three case studies applied to the Alhambra building complex and the street networks of Manhattan and Sweden illustrate that the defined wholeness captures fairly well human intuitions on the degree of life for the geographic spaces. We further suggest that the mathematical model of wholeness be an important model of geographic representation, because it is topological oriented, which enables us to see the underlying scaling structure. The model can guide geodesign, which should be considered as the wholeness-extending transformations that are essentially like the unfolding processes of seeds or embryos, for creating built and natural environments of beauty or with a high degree of wholeness.     

基于SOFM 的区域界线划分方法

区域分异研究是人们对地理环境认知深度和自然地理研究水平的重要标志之一, 划定分区界线就成为一 项迫切而意义重大的工作, 尤其是在气候复杂、地貌多样的我国西南高原、山地组合区。云南省南部地区由于多季 风系统和大地形作用的影响, 气候复杂多样。雨季, 温暖湿润的西南夏季风给研究区西部带来大量降水, 东部雨量 少; 干季, 整个研究区主要在西风南支急流控制之下, 天气晴朗、少雨, 同时也使得植被种类及盖度差别较大。基于 研究区30 个气象台站的海拔高度、多年平均气温和降水、风速、活动积温、潜在蒸散以及MODIS- EVI 等数据, 利用 神经网络技术构建了非线性分类器, 即自组织特征映射模型( SOFM) , 对所有气象台站进行了聚类研究。结果显示, 哀牢山成为阻挡北来冷空气进入西南山地的屏障, 是我国冬季东北风和夏季西南风的分界线, 因此也成为研究区 东、西两类气候的分界线。SOFM网络应用于地形复杂、地貌多样的生态地理区域分异研究, 基本能反映不同区域之 间界线两侧的相似性和差异性, 能够揭示一个由量变到质量过程的连续性, 不失为一种较好的综合自然地理区划 方法。     

地学计算的研究进展与问题分析

对西方地学计算的起源、概念、知识体系以及存在争议的问题进行了概括地介绍和评述。地理计算的发展动因在于探索空间复杂性的需要,发展源流则在于计算科学,技术主线可以归结为：计算机科学→计算科学→计算地理学→地理计算科学。地理计算与地理信息系统(GIS)具有密切关系,需要运用定量地理学的全套工具,横跨自然、人文两大领域,可望成为一个全新的知识领域,甚至有可能发展出一种新的研究范式。地理计算科学在西方发展迅速,但也存在一些令人不安的问题,其中之一便是缺乏知识建构的核心。由于地理计算具有超越地理学的意向和趋势,本文建议以计算地理学为主体之一,以“利用模型寻求理解”为原则,建立一个相对收敛的知识体系。     

航海用DDM向非航海用转换时的整体偏差补偿方法

针对航海用数字水深模型（DDM）向非航海用转换这一问题,提出了一种用整体偏差值补偿来提高转换精度的方法。首先建立航海用DDM整体性偏差值与海底地形复杂因子、海图比例尺之间的关系;其次依据上述关系预先推算航海用DDM的整体偏差值;最后将整体偏差值补偿到转换前的航海用DDM的模型点上,以提高转换后的非航海用DDM精度。试验证明：①所提的方法可行,可提高转换后非航海用DDM的精度;②转换后非航海用DDM精度提高的程度与海底地形复杂因子和海图比例尺有关。