英语翻译To introduce some of the language of geographic informat

英语翻译
To introduce some of the language of geographic information systems with a simple first example,let's examine an application of a simple manual GIS.This GIS arises during the early steps in developing a site for a golf course.We assume for this discussion that a specific site is already under consideration.A planner has sought out and gathered together a group of existing datasets for the site.This group might include a topographic map,a blue-line map of parcel boundaries from the local municipal planning agency,and an aerial photograph of the site (Figure 1.2).We refer to these three datasets - 2 maps and a photograph - as data layers or data planes.
The topographic map depicts several kinds of information.Elevation on the site is portrayed as a series of contour lines.These contour lines provide us with a limited amount of information about the shape of the terrain.Certain kinds of land cover are indicated by colors (often blue for water,green for vegetation) and textures or patterns (such as repeated patterns denoting wetlands).A number of kinds of man-made features are indicated,including structures and roadways,typically by lines and shapes printed in black.In many cases,the information on this map is five to fifteen years out of date,a common situation resulting from the rate of change of land cover in the area and the cycle of map updates.Each of these different kinds of information,which we may decide to store in various ways,is called a theme.
The map from the local planning agency provides us with additional and different kinds of information about the area.This map focuses principally on the infrastructure:legal descriptions of the proposed golf course property boundaries,existing and planned roadways,easements of different kinds,and the locations of existing and planned utilities such as potable water,electric and gas supplies,and the sanitary sewer system.The planning map is probably not at the same scale as the topographic map; the former is probably drawn at a larger scale than the latter.Furthermore,the two aren't necessarily based on the same map projection (see section 6.6.1).For a small area like our golf course,the approximate scale of the data is probably more important than the details of the map projection.

引进一些的语言,地理信息系统,以一种简单的一个例子,让我们研究的一个应用一个简单的体力劳动了38.90% .这一地理时,在先期开发的土地,用以兴建一座高尔夫球场.我们假设这方面的讨论,具体地点也已在考虑.企划已找出并聚集现有的一组数据的网站.这个小组可能包括地形图,蓝线图的界址,由当地市规划局 和空中的现场照片(图1.2 ) .我们所说的这三个数据- 2地图和一张照片作为数据层或数据机.地形图,描绘了几种信息.海拔在网站被描绘成一系列的等高线.这些等高线,为我们提供了有限的资料形状的地形.某些类型的土地复盖296-308颜色(通常为蓝色水 绿色植被)和纹理或图案(如重复模式指湿地) .若干种人造特征表明的,包括建筑物,道路,通常以线条和形状印黑色.在许多案件中,关于这个地图是五年至十五年有期徒刑过时 一种常见情况产生率的变化,土地复盖面积和周期图 更新.所有这些不同种类的信息,我们可以决定商店以各种方式,是所谓的主题.该地图由地方规划机构,为我们提供更多不同类型的资料区.这幅地图的重点主要集中在基础设施:法律说明建议的高尔夫球场财产的界限,现有及规划道路,地役权不同,和地点的现有和计划工具如饮水,电力和天然气供应,和下水道系统.规划图,很可能无法在同一尺度的地形图; 前者可能是下结论的规模已超过了后者.此外,双方也未必是基于同一地图投影(见6.6.1节) .一丁点像高尔夫球场,近似规模的数据,可能是更重要的较详细的地图投影.