分形,分维及其在地图制图中的应用   总被引：2，自引：0，他引：2  

王桥  吴纪桃 《地图》1992,(3):5-11

分形理论是一门新兴的数学分支,在自然科学的许多领域中具有广泛的应用。近年在地学中的应用也十分活跃。本文结合国内外学者的有关成果和作者的一些工作,简要介绍分形理论的基本概念以及在地图制图学中的若干应用,同时指出分形理论用于地图制图学中有关问题研究的价值和前景。  相似文献   

朝鲜的前寒武系和下古生界     

王桥 《海洋地质译丛》1991,(6):29-37

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International refugees: a geographical perspective     

Demko GJ  Wood WB 《The Journal of geography》1987,86(5):225-228

In the modern era, the world's refugee problem has changed magnitude and location; it has expanded from a local to a continental, and now global, scale issue. About 90% of the world's 10 million refugees are from developing countries, and over 90% of these will stay there. Refugee generating and receiving countries are concentrated in 5 world regions: Central America, Southwest Asia, Southeast Asia, and Sub-Saharan Africa. Each concentration is unique and is associated with a particular set of regional conflicts. International efforts address short-term relief needs, whereas political instability and repression that generate refugees continue unabated. Refugees along sensitive border regions affect bilateral relations, large groups of refugees can pose political and security problems for the host country, and disputes over refugee policies and their implementation can complicate diplomatic ties. Some highlights of the data follow. 1) The 3 million cross-border refugees and 5.5 million internally displaced persons make the many governments in Sub-Saharan Africa increasingly dependent on Western assistance to solve their problems. Refugees are fleeing armed conflict, tribal violence, and drought, and often generate additional regional turmoil. 2) 3-4 million Afghans have fled their country since the 1978 Marxist coup; about 2.5 million have entered Pakistan. Most choose to remain in camps near the Afghanistan border where they are targets of cross-border attacks. 3) 1.2 million Salvadorans, Guatemalans, and Nicaraguans live outside their native countries. Official refugee and unofficial migrant populations are active in various rebel insurgencies, contribute to strained bilateral relations and tensions in border areas, and are the subject of heated political debate in host countries. 4) 90% of the 1.7 million Indochinese who fled from 1975-May 1986 have been resettled; 168,000 refugees remain in 1st-asylum camps, not including 240,000 Khmer without refugee status, in temporary camps in Thailand. Thailand's large refugee population is involved in factional strife, smuggling, and guerrilla activities. The Thai are particularly concerned about Hmong refugees, who are accused of opium cultivation and destruction of Thai forests through slash-and-burn cultivation. 5) Nearly 62% of the thousands of present Vietnamese refugees to Hong Kong have been in camps 3 years, and 17% 6 years. Many have turned to crime, alcohol, drugs, or prostitution.  相似文献   

线状地图要素的自相似性分析及其自动综合     

王桥 《武汉大学学报(信息科学版)》1995,(2)

通过线状地图要素的自相似性分析和分维估值，研究了线状地图要素的形状结构特征随量测尺度和比例尺变化的规律，并在此基础上，提出了旨在使综合过程自适应进行和保持图形形状特征的线状要素自动综合的方法。  相似文献   

地图图斑形状特征的量化及其分形模型研究     

吴纪桃  王桥 《武汉大学学报(信息科学版)》1995,(2)

运用分形几何原理，提出了量化地图图斑形状特征的分形模型，讨论了模型中的参数──形状因子和分维的意义及求法，给出了制图现象形状特征量化的一种新途径。  相似文献   

地图投影的坐标变换——第五讲 方位投影的反解公式     

方炳炎  王桥 《地图》1995,(3):56-59

对方位投影的坐标反解在正轴投影情况下是比较容易的，可以直接利用投影公式反解，而在斜轴与横轴情况下，首先需将投影的直角坐标反解为球面坐标Ａ、Ｚ，而后再将球面坐标反解为地理坐标ψ、λ。  相似文献   

面向制图线自动综合的分维估值方法及其应用     

王桥  吴纪桃 《测绘信息与工程》1995,(1)

本文将分形理论中的分维计算与数据压缩中的光栏法基本原理相结合，提出了一种专门用于制图线自动综合的分维估值方法及其相应的自动综合算法。用该方法求出的分维数，可从数量上反映制图线形状结构特征随描述它的阈值变化的规律，基于该方法的自动综合算法可较好地实现制图线自动综合过程的数量化和模型化，并使制图线形状结构特征得以有效保持。  相似文献   

地图曲线的分形插值   总被引：3，自引：0，他引：3  

王桥 《武测科技》1995,(4):8-13

将分形插值函数作为一种地图图形数据处理的新型工具进行了扼要介绍，讨论了有关的性质，算法，并给出了一些实例。  相似文献   

地图投影的坐标变换   总被引：2，自引：0，他引：2  

方炳炎  王桥等 《地图》1995,(1):47-52

地图投影的坐标变换方炳炎，王桥，胡毓钜编者按：本刊编辑部常收到读者咨询不同地图投影之间的投影交换问题，因为在遥感制图与机助制图方面常会遇到这种处理，为此请有关专家撰写这个讲座。第一讲概述在计算机辅助地图制图和地理信息系统处理信息资料时，常常需要将一种...  相似文献   

一种新的地图数据检索方法及其应用软件   总被引：6，自引：0，他引：6  

王桥 《武汉测绘科技大学学报》1993,18(4):13-19

本文提出了一种新的实用地图数据检索方法－“放大镜”式地图数据检索，建立了相应的软件系统，并讨论了该方法的数学基础、软件的特点，还给出了应用实例? ?  相似文献