地理信息系统考试习题

地理信息系统考试试题一、简答题（70分）1. 什么是地理信息系统?它与地图数据库有什么异同?与地理信息的关系是什么?2. 通过课程的学习，你对地图投影与地图比例尺之间的关系有什么新的认识？3. What are the development periods, status quo and the most urgent key problems to be solved in GIS?4. How Geo-Spatial Information describe the true word in digital form?5. Describe metadata conception, types and its function.6. Illustrate the characteristics of GIS spatial Database and its basic organizing pattern.7. Describe metadata and its types and function.二、编程题（30分）设有一个公路矢量数据文件W.TXT (x1,y1,x1,y2,……)，试求：（1）该公路的总长度（2）该公路中点坐标（该点到两端点的线路长度相等）答案：1. 什么是地理信息系统?它与地图数据库有什么异同?与地理信息的关系是什么?地理信息系统简称为GIS。

关于它确切的全称，多数人认为是Geographical Information System，也有人认为是Geo-Information System。

不同领域、不同专业对GIS 的理解不同，目前没有完全统一的被普遍接受的定义：1）美国学者Parker认为“GIS是一种存贮、分析和显示空间与非空间数据的信息技术”。

2）加拿大的Roger Tomlinson认为“GIS是全方位分析和操作地理数据的数字系统”。

3）Goodchild把GIS定义为“采集、存贮、管理、分析和显示有关地理现象信息的综合系统”。

4）Burrough认为“GIS是属于从现实世界中采集、存储、提取、转换和显示空间数据的一组有力的工具”。

5）俄罗斯学者也把GIS定义为“一种解决各种复杂的地理相关问题，以及具有内部联系的工具集合”。

6）美国国家地理信息与分析中心给出的定义：“GIS为了获取、存储、检索、分析和显示空间定位数据而建立的计算机化的数据库管理系统”。

7）英国教育部认为：“GIS是一种获取、存储、检索、操作、分析和显示地球空间数据的计算机系统”。

这些定义，有的侧重于GIS的技术内涵，有的则强调GIS的应用功能。

本人倾向认为：地理信息系统应该是在计算机硬、软件系统支持下，对整个或部分地球表层（包括大气层）空间中的有关地理分布数据进行采集、储存、管理、运算、分析、显示和描述的技术系统。

地理信息系统处理、管理的对象是多种地理空间实体数据及其关系，包括空间定位数据、图形数据、遥感图像数据、属性数据等，用于分析和处理在一定地理区域内分布的各种现象和过程，解决复杂的规划、决策和管理问题。

地图数据库可以从两个方面来理解：一是把它看作是软件系统，即“地图数据库管理系统”；一是把它看作是地图信息的载体——数字地图。

地图数据库使地图信息表现为结构化的数据集合，可以为多个部门使用，从而扩大了其使用范围，减少了大量的不必要的用于重复获取数据而消耗的人力物力；另一方面，地图数据库中的信息（地图数据）可以能以多种方式进行处理，为不同的应用提供决策依据。

地理信息系统与地图数据库的共同点在于：都有地图编辑、输出、查询、检索功能，地图数据库也是GIS的重要组成部分，为综合图形和属性进行深层次的空间分析提供辅助决策信息。

本质区别在于：地图数据库侧重于数据的查询、分类及自动符号化等，强调数据显示、管理而非数据分析，地理信息系统不仅实现了地理空间信息的采集、储存、管理，更重要的在于其空间分析功能。

地理信息是有关地理实体的性质、特征和运动状态的表征和一切有用的知识，它是对表达地理特征与地理现象之间关系的地理数据的解释。

地理数据则是各种地理特征和现象间关系的符号化表示，包括空间位置、属性特征及时域特征三部分。

地理信息是地理信息系统赖以进行空间分析的数据基础和理论基础2. 通过课程的学习，你对地图投影与地图比例尺之间的关系有什么新的认识？一概念阐述：（1）地图投影：就是把地球椭球面上的点、线(即经纬线)投影在平面图纸上。

它是研究把地球椭球体面上的经纬网按照一定的数学法则转绘到平面上的方法及其变形问题。

地图投影的方法有几何法和解析法。

几何法是以平面、圆柱面、圆锥面为承影面，将曲面（地球椭球面）转绘到平面（地图）上的一种古老方法，这种直观的透视投影方法有很大的局限性。

解析法是确定球面上的地理坐标与平面上对应点的直角坐标之间的函数关系。

将地球椭球面上的点投影到平面上，必然会产生变形，这是由于椭球面是一个不可展的曲面所决定的。

在地球面上一定间隔的经差和纬差构成经纬网，相邻两条纬线件的许多网格具有相同的形状和大小。

但投影到平面后，往往产生明显的差异，这就是投影变形导致的。

这种变形表现在形状和大小上发生了变形，实质上，就是由投影产生了长度变形、面积变形、角度变形。

（2）地图的比例尺，是指地图上某线段的长度与实地相应线段的水平长度之比。

其表现形式有数字比例尺、文字比例尺和图解比例尺。

地图上的比例尺又分为主比例尺和局部比例尺。

在计算地图投影或制作地图时，将地球椭球按一定比率缩小而表示在平面上，这个比率称为地图的主比例尺，或称普通比例尺。

地图上除保持主比例尺的点或线以外其他部分的比例尺称为局部比例尺。

局部比例尺的变化比较复杂，它们依投影种类、投影性质的不同，常常是随着线段的方向和位置而变化的，对于某些需要在图上进行量测的地图，便要采用一定的方式设法表示出该图的局部比例尺。

二两者的关系：地图投影的选取决定于地图的应用及其比例尺大小，例如,墨卡托投影适用于海图，其面积变形随着纬度的增高而加大，但其方向变形很小；横轴墨卡托投影的面积变形随着距中央经线的距离的加大而增大，适用于制作不同的国家地图。

等角投影常用于航海图、风向图、洋流图等。

现在世界各国地形图采用此类投影比较多。

等积投影用于绘制经济地区图和某些自然地图。

对于大多数数学地图和小比例尺普通地图来说，应优先考虑等积的要求。

地理区域，诸如国家、水域和地理分类地区（植被、人口、气候等）相对分布范围，显然是十分重要的内容。

任意投影常用作数学地图，以及要求沿某一主方向保持距离正确的地图。

常用作世界地图的投影有墨卡托投影、高尔投影、摩尔威特投影、等差分纬线多圆锥投影、格灵顿投影、桑森投影、乌尔马耶夫投影等。

3. What are the development periods, status quo and the most urgent key problems to be solved in GIS?Answer：(1)The development course of GIS ：①The phase of GIS appearance:In 1963,Canada survey scientist R.F.Tomlinson firstly put forward the term of GIS, and builds the first GIS in the world-- CGIS that is used to manage natural resources.②The phase of GIS consolidation:In 1970s, Due to the effect of computer hardware and software technology development, GIS technology is developed to the practical direction. Some advanced countries successively built many professional LMIS and GIS. Meanwhile, GIS software market is very active. The government, commercial company and university began to pay attention to GIS technology and GIS become a domain that attracts everyone.③The phase of GIS popularization and application:In 1980s, With the improvement of ratio of capability and price of figure workstation and PC, Computers and spatial information system are widely applied. GIS application began to change from the spatial data management to spatial decision analysis with the development of GIS software and hardware.④In 1990s,With the building of geography information industry and the popularization of digital information product in the world, GIS goes into a large number of households and becomesa assistant and tool of people's life, study and work.(2) Critical questions must be solved in the future:①Methodology of GIS design and realization;②Functions of GIS;③Management and operations of multi-media GIS;④Deep process of geographical information in GIS;⑤Visual and VR technology of spatial information.⑥The information islands and the information sharing problems4. How geo-spatial information describe the true world in digital form? Answer:We subdivide the true world, the earth’s surface into meaningful entities or objects that can be characterized. Each accident that happens on the true world can be digitized. The geometrical entities of geo-spatial include several primitive types such as point, line, polygon, surface, volume and so on. The model of the earth, in this way, can be represented in a spatial database.The digital representation of geographical information is usually in two ways: vector and raster.Vector Data Structure is based on MA—Mathematic Analysis, which uses point, line and arrow to describe geographical entities in a coordinate. So Vector Data Structure is in order. Concretely speaking, Vector Data Structures are based on elemental points, whose locations are known to arbitrary precision. Many computer graphics and computer-aided-design systems use vector-like models as their internal data organization, using primitives such as points, lines and circles.Since the geo-spatial is so complex, that vector data structure can’t represent it in detail and clearly. We think of using raster data structure.Raster data structure is based on LA—Liner Math Analysis. In a raster structure, a value for the parameter of interest-elevation in meters above datum, land use class form a specified list, plant biomass in grams per square meter, and so forth is developed for every cell in a array over space. This kind of data structure is intuitive, we might imagine a survey team determining elevations at regular distances along lines of constant latitude.5.Describe metadata and its types and function.Answer:When you look through a map,you may understand something on it,no matter which country this map was made in,but you can never understand anything from a spatial data.You need a kind of data to tell you something about it,that is metadata.Till now,there is no exact definition about it,it is generally considered as such data that used to illustrate other datas.To better understand metadata and use metadata,we classify it into serval types.According to its content,it is classified into three types:Scientific research metadata,which helps users to get data from all kinds of sources and other related information;Assess metadata,which is used to assess the use of data;Model metadata,used to describe the data model.According to the object it describes,it is classified into other three types:Data layer metada,to describe each data in data assembly;Attribute metadata,related to attribute data;Entity metada,to describe the whole data assembly.According to its function in the system,it is classified into two types:system level metadata,to realize the file-system characters or to manage the data information in the file system;Application-level metadata,which helps users to search,estimate,visit and manage data as well as some other information related to data users.According to its function,it is classified into two types:Illustration metadata ,specially serves when users use data:Control metadata,used to control the operate process of a computer.The main function of metadata include five aspects:The first one is to help the data produced unit to efficientlly manage and maintain spatial data,to establish data documentation,and to ensure the understanding of data.Second,the metadata will provide the data-produced unit with lots of information about data storage,data classification,data content,data quality,data clearing house,data sale and so on,so as to be convenient for users to search and reach spatial data.The third one is to provide methods or ways of searching data through the Interner,and assitant information about data exchange and transportation.The forth one is to help users to understand data,so as to make correct judgement about shether the data could meet their needs.The last one is to provide some information that is helpful for users to process and convert useful data.6. Illustrate the characteristics of GIS spatial Database and its basic organizing pattern.Answer:Characteristics:(1)Traditional database system manages discrete,low-correlative numbers and strings.Geographic information data is continuous, and has a strong spatial relevance.(2) Traditional database system manages little types of entities, and the spatial relationship among them is usually simple and fixed.The entity type of geographic spatial data is various,among which there is a complex spatial relationship,and some new relationship may come about.(3) Traditional database system usually stores data recorded of the equal length. Geographic spatial data often includes unfixed-length record,and the data items may be large and complicated,because different spatial object has different coordinate string length.(4) Traditional database system only handles and inquires information of words and numbers.Spatial database requires much spatial data operating and inquiring.Basic organizing pattern:Hybrid model:Its basic concept is to use two sub-systems to store and search spatial data and attribute data separately.Attribute data is stored in conventional RDBMS while geometric data isstored in spatial data manage system.These two sub system are connected by a kind of totem.While searching the object,it is essential to inquire the two sub systems at the same time,then combine their answers.Considering part of this hybrid model is based on standard RDBMS,storing and searching data seems to be more effective and reliable.But as the rules of the two sub systems are different from each other,the data stored outside RDBMS may sometimes lose its meaning.Besides,the qualification of the integrality of data is likely to be destroyed.7. Describe metadata and its types and function.Answer:When you look through a map,you may understand something on it,no matter which country this map was made in,but you can never understand anything from a spatial data.You need a kind of data to tell you something about it,that is metadata.Till now,there is no exact definition about it,it is generally considered as such data that used to illustrate other datas.To better understand metadata and use metadata,we classify it into serval types.According to its content,it is classified into three types:Scientific research metadata,which helps users to get data from all kinds of sources and other related information;Assess metadata,which is used to assess the use of data;Model metadata,used to describe the data model.According to the object it describes,it is classified into other three types:Data layer metada,to describe each data in data assembly;Attribute metadata,related to attribute data;Entity metada,to describe the whole data assembly.According to its function in the system,it is classified into two types:system level metadata,to realize the file-system characters or to manage the data information in the file system;Application-level metadata,which helps users to search,estimate,visit and manage data as well as some other information related to data users.According to its function,it is classified into two types:Illustration metadata ,specially serves when users use data:Control metadata,used to control the operate process of a computer.The main function of metadata include five aspects:The first one is to help the data produced unit to efficientlly manage and maintain spatial data,to establish data documentation,and to ensure the understanding of data.Second,the metadata will provide the data-produced unit with lots of information about data storage,data classification,data content,data quality,data clearing house,data sale and so on,so as to be convenient for users to search and reach spatial data.The third one is to provide methods or ways of searching data through the Interner,and assitant information about data exchange and transportation.The forth one is to help users to understand data,so as to make correct judgement about shether the data could meet their needs.The last one is to provide some information that is helpful for users to process and convert useful data.二、编程题#include<stdio.h>#include<math.h>main(){FILE *fp1;float posx[100],posy[100];float a[1000];int i=0;int j=0;int n=0;float sum=0.0,sum2=0.0;for(i=0;i<100;i++){posx[i]=NULL;posy[i]=NULL;}i=0;fp1=fopen("d:\\w.txt","r");while(!feof(fp1)){fscanf(fp1,"%f,%f,%f,%f,",&posx[i],&posy[i],&posx[i+1],&posy[i+1]);i+=2;n=i;}printf("n=%d\n",n);for(i=0;i<n-2;i++){a[i]=sqrt((posx[i+1]-posx[i])*(posx[i+1]-posx[i])+(posy[j+1]-posy[j])*(posy[j+1]-posy[j]));printf("a[i]=%f\n",a[i]);}for(i=0;i<n;i++)sum+=a[i];printf("sum=%f",sum);i=0;sum=sum/2;while(sum2!=sum){sum2=sum2+a[i]; i++;}printf("x=%f,y=%f",posx[i],posy[i]);fclose(fp1);}。