【译】QGIS培训教程-4.1属性数据

4. Module: 对矢量数据进行分类(Classifying Vector Data)

4.1. Lesson: 属性数据(Attribute Data)

到目前为止,我们对地图所做的更改并没有影响展示的要素。换句话说,所有的土地使用地区都是一样的,并且,所有的道路看起来也一样。当我们在看图时,读图者不会从图上独到任何道路的信息,他们只能看到某区域一条特定形状的路而已。(Up to now, none of the changes we have made to the map have been influenced by the objects that are being shown. In other words, all the land use areas look alike, and all the roads look alike. When looking at the map, the viewers don’t know anything about the roads they are seeing; only that there is a road of a certain shape in a certain area.)

但GIS的整体优势是地图上所有可见的对象都具有属性。GIS 中的地图并不只是图片。它不仅能描述物体的位置,而且带有这些对象的信息。(But the whole strength of GIS is that all the objects that are visible on the map also have attributes. Maps in a GIS aren’t just pictures. They represent not only objects in locations, but also information about those objects.)

本课目的:(The goal of this lesson: 探索对象的属性数据,并了解这些数据的用途。(To explore the attribute data of an object and understand what the various data can be useful for.)

4.1.1.  跟我做:属性数据Follow Along: Attribute data

打开的 places图层的属性表 (如有必要,请参阅”操作矢量数据”一节)。看一看,哪些字段信息最适合用来做标签呢,为什么?(Open the attribute table for the places layer (refer back to the section “Working with Vector Data” if necessary). Which field would be the most useful to represent in label form, and why?)

Check your results

4.1.2. 小结In Conclusion

你现在已经知道如何查看你所使用的数据的属性表了。只有带有我们关心的信息的数据集才是有用的。如果你知道你需要哪些属性,你可以快速判断某个给定的数据集是否有用,否则我们需要寻找另一个具有必需的属性数据的数据集。(You now know how to use the attribute table to see what is actually in the data you’re using. Any dataset will only be useful to you if it has the attributes that you care about. If you know which attributes you need, you can quickly decide if you’re able to use a given dataset, or if you need to look for another one that has the required attribute data.)

4.1.3. 下节提要What’s Next?

不同的属性可用于不同的目的。其中一些可以直接作为读图标签。下节课我们将重点学这个内容。(Different attributes are useful for different purposes. Some of them can be represented directly as text for the map user to see. You’ll learn how to do this in the next lesson.)

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