基于数学形态学的第四系地层遥感影像分割

利用数学形态学的方法对遥感影像的第四系地层进行了影像分割实验。经实验结果得出,利用数学形态学的基本运算组合成的各种算子:高、低帽变换、滤波与阈值截取相结合的增强方法,通过选择合适的结构元素,对图像进行预处理后,就可以用形态学方法对第四系地层进行影像分割。经过处理的遥感影像,能够更有效地提取影像的目标。实验结果表明了本文所提的方法的有效性。最后,对形态学方法的不足之处和将来的研究方向展开了讨论。     

车载激光扫描数据分类支持下的路面数据提取

车载激光扫描系统可以快速采集道路及两旁的建筑物、植被、电杆等地物的点云数据,而点云数据的分类提取是车载激光扫描系统应用的关键。本文选用全景激光移动测量系统获取的激光点云数据,分析了路面点云数据的特征,采用渐进格网法进行了路面点云数据的提取研究;通过试验区的实例验证,取得了较好的分类效果。     

Late Quaternary tephrostratigraphy and pollen stratigraphy of Uwa Formation,Shikoku Island,SW Japan: Reconsidering the MIS 11 super-interglacial horizon

We investigated a late Quaternary terrestrial sedimentary sequence (Uwa Formation) in core IC2, from a site adjacent to that of the reported core IC on NW Shikoku Island, SW Japan, and developed its tephra and pollen stratigraphy to refine the age model of the formation. First, we identified 19 horizons with high glass shard concentrations in the IC2 core sediments as possible tephras or cryptotephras, and correlated them with reported tephras on the basis of the major- and trace-element compositions of their glass shards. All correlated widespread tephras and cryptotephras were products of volcanoes in the Kyushu volcanic zone (Aso, Kakuto, Aira, Ata, and Kikai calderas). Second, we confirmed the presence in core IC2 of two pollen zones dominated by Quercus subgen. Cyclobalanopsis, which is an indicator of very warm interglacial vegetation. In the Japanese Islands, these two vegetation zones have usually been considered to characterize marine isotopic stages (MISs) 1 and 11. A previous study of the Uwa Formation correlated the upper pollen zone to MIS 1, but the lower zone was not correlated to MIS 11; rather, it was inferred to be older than MIS 12 because it was stratigraphically below the “Oda” tephra (equivalent to a distal Kasamori 5 [Ks5] tephra [MIS 12]). In this study, however, noting that the Naruohama-IV tephra (Nh-IV; MIS 10d) and Ks5 cannot be distinguished by their shard chemistries, we inferred that the suggested “Oda” tephra actually correlates to Nh-IV, rather than to the Ks5 tephra. By re-assigning the “Oda” tephra to Nh-IV, we could correlate the underlying Quercus subgen. Cyclobalanopsis-abundant zone to MIS 11 and, consequently, a pair of pollen zones indicating cool and warm conditions below the MIS 11 pollen zone to MISs 12 and 13, respectively. The resulting age model whereby tephra and pollen constraints are integrated showed a roughly constant sedimentation rate from MIS 13, without any long-term gaps; further, our MIS 13 horizon in core IC2 corresponds to the reported 1 Ma tephra horizon in core IC. Therefore, these findings represent a dramatic change in the Uwa Formation age model and validate the Uwa Formation as one of the most useful terrestrial archives of Quaternary tephrostratigraphy and paleoclimatic fluctuation in SW Japan.     

Maximized erosion at the last glacial maximum revealed by thermoluminescence thermochronometry

Increased erosion rates during the last 2 Myr of Earth history are commonly associated with widespread glaciation and global cooling. However, whether erosion rates actually increased during that period of time remains debated. This is in part because the respective role of fluvial and glacial erosion is difficult to assess, and because many existing techniques used to estimate erosion rates may be affected by averaging biases that may produce increased erosion rates towards the present. Here, we apply thermoluminescence thermochronometry to granitic bedrock samples of the southern-central Chilean Andes, a region which experienced a full transition from glacial-humid to fluvial-dry conditions during the Quaternary. Inverse modelling of the thermochronological data enables us to extract unbiased time series of erosion rates during the last ∼100 kyr. We find that erosion rates were systematically higher during around the last glacial maximum than at present, with differences exceeding an order of magnitude. Our findings indicate that glacial erosion is probably more efficient than fluvial erosion and imply that erosion has remained transient during the Quaternary.     

利用球体剖分瓦块构建真三维数字地球平台

全球离散网格是面向空间大数据的模型框架,常用于构建数字地球平台。基于球体的剖分瓦块不仅可以构建真三维的数字地球模型,而且可以实现天地一体化的空间数据集成、融合、表达和应用。本文详细论述了球体大圆弧QTM八叉树网格的剖分原理、网格几何特征分析和编解码方法等理论体系,并利用剖分瓦块实现了球体的任意分割以及地下、地表和空中实体的可视化建模。研究表明,球体QTM网格具有剖分规则简单、体系规整、几何特征明晰,适用性强等特点,尤其是可以推广到椭球。因而,该方案可用于天地一体化的空间数据的组织、管理与应用。     

Stability Regions and Quasi-Periodic Motion in the Vicinity of Triangular Equilibrium Points

The regions of quasi-periodic motion around non-symmetric periodic orbits in the vicinity of the triangular equilibrium points are studied numerically. First, for a value of the mass parameter less than Routh's critical value, the stability regions determined by quasi-periodic motion are examined around the existing families of short (L^s ₄) and long (L^l ₄) period solutions. Then, for two values of μ greater than the Routh value, the unified family L^sl ₄, to which, in these cases, L^s ₄ and L^l ₄ merge, is considered. It is found that such regions surround in general the linearly stable segments of the corresponding families and become smaller as the mass ratio increases. This revised version was published online in July 2006 with corrections to the Cover Date.     

BOOK REVIEWS

Books reviewed in this article: Aerial Photography and Remote Sensing Aerial photography and image interpretation for Resource Management . DAVID P. PAINE . Analytical Models and Techniques Spatial Processes Models and Applications A. D. CLIFF AND J. K. ORD Quantitative and Statistical Approaches to Geography: A Practical Manual JOHN A. MATTHEWS . Cartography and Maps Map Data Processing . HERBERT FREEMAN AND GOFFREDO G. PIERONI , eds. Computer-assisted Cartography: Principles and Prospects, 1982 . MARK S. MONMONIER . Cultural Navajo Architecture: Forms, History, Distributions . STEPHEN C. JETT AND VIRGINIA E . SPENCER . Rational Landscapes and Humanistic Geography . EDWARD RELPH . Economic The Structure and Control of a State Economy . W. L. L'ESPERANCE . Economic Geography . JAMES O. WHEELER AND PETER O. MULLER . The Myth of the Family Farm: Agribusiness Dominance of U.S. Agriculture . INGOLF VOCELER . Libya: The Experience of Oil . J. A. ALLEN . Geography of Public Finance, Welfare Under Fiscal Federalism and local Government Finance . ROBERT BENNETT . Environmental Management, Resources, and Systems Mountains and Man . LARRY W. PRICE . Environmental Geology . DONALD R. COATES . An Introduction to Environmental Systems . G. H. DURY . The Environment: Chinese and American Views . Edited by LAURENCE J. C. MA AND ALLEN G. NOBLE . Land Use in America . RICHARD H. JACKSON . Medical Conceptual and Methodological Issues in Medical Geography . MELINDA S. MEADE (ed.). Philosophy and Geographic Thought Birds in Egg/Eggs in Bird . GUNNAR OLSSON . PhysicaI Climatology: Selected Applications . J. E. OLIVER . Geomorphological Techniques . ANDREW GOUDIE (ed.). Political Politics, Geography and Behaviour . RICHARD MUIR AND RONAN PADDISON . The State of the World Atlas . MICHAEL KIDRON AND RONALD SECAL . Population The Population of the South . DUDLEY L. POSTON , JR . AND ROBERT H. WELLER , eds. Regional Latin America: Economic Development and Regional Differentiation . ARTHUR MORRIS . Developing the Amazon . EMILIO F. MORAN . Western Europe: A Systematic Human Geography . BRIAN W. ILBERY . Settlement Systems in Sparsely Settled Regions: The United States and Australia . RICHARD E. LONSDALEAND JOHN H. HOLMES , eds. African Perspectives: The Economic Geography of Nine African States . HARM DE BUJ AND ESMOND MARTIN , eds. Rural Nonmetropolitan America in Transition . AMOS H. HAWLEY AND SARA MILLS MAZIE , eds. Social Crime and Environment . R. NORMAN DAVIDSON . The Ghetto: Readings with Interpretations . JOE T. DARDEN , ed. Urban Urban Problems and Planning in the Developed World . MICHAEL PACIONE (ed.) Problems and Planning in Third World Cities . Edited by MICHAEL PACIONE . The City in West Europe . D. BURTENSHAW , M. BATEMAN , AND C. J. ASHWORTH .     

第四纪与环境

目前最大的环境问题是由人类排放CO     

球面离散网格与球体离散网格的比较研究

测地线在球体剖分中扮演着十分重要的角色,它保证了球体剖分网格单元的形体简单性和空间关系的一致性。本文基于对欧式空间和流空间的数学认识,探讨了球体剖分的评价标准,提出了基于大圆弧QTM的球体八叉树剖分方法,并指出作为一种大尺度的集成三维空间数据模型,全球三维离散网格是地理信息科学的一个新的发展方向。     

GIS专题数据库中多层注记重叠问题的解决与自动配置

GIS专题数据库中面状对象的注记一般会自动配置在图形的重心位置。当同一个面状对象在多个数据层中被赋予不同的属性定义时,注记符号和文字将会重叠在同一个位置。当使用的GIS建库软件存在这方面的缺陷时,解决多层注记重叠、自动重新配置注记符号这一命题就显得至关重要。本文以张家界市武陵源城镇地籍数据为例,从多边形形状度量入手,给出基于Delaunay三角网法的骨架线提取算法,较好地解决了多数据层注记重叠和注记符号自动配置问题,提高了工作效率。