Background

The power of layers in GIS:

From ESRI's 'Key Aspects of GIS'

Introduction to Data

GIS is all about data and until you appreciate how to manage that data, you can never really unlock the power of GIS. Both GIS and CAD (computer assisted drafting) can be used to make maps (in CAD often thought of instead as a plan). Both rely on the concept of layers to overlay information (see left). The fundamental difference between GIS and CAD is the way in which they represent spatial objects on these layers. In CAD, you draw spatial objects (e.g. lines, polylines, polygons, solids, etc.) that are referred to as entities and these reside in a drawing. By contrast, in GIS you don't draw per se, but instead you load a reference to data (e.g. in ArcMap you use the Add Data tool ), which you choose how you want to display. Although CAD can be used to do GIS-type things, and GIS can be used to draw, neither are very good at doing what the other was fundamentally designed to do. In CAD you can draw very accurately and precisely with a multitude of options. This is extremely useful for design work, in which you want to create something. In GIS, spatial data lies behind everything. GIS is much more powerful then CAD when it comes to doing analyses, querying data, and managing large quantities of data. Over the next two weeks, we will help you better understand where data comes from and how it is manipulated in GIS.

Why we're Covering it

You should be aware of the plethora of data sources from which you can get GIS data and use it for context or analysis, and how to edit and make your own data. ArcGIS makes some of these choices so easy for you that you can get yourself in trouble. These skills will be crucial in your projects and the if you intend to use GIS in your career to do more than just make location maps (i.e. lab 01).

Learning Outcomes

These lectures, readings and Labs 03 & 04 all help fulfill primary learning outcomes 1, 2, 3 & 4.

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Lectures and Podcasts

Quiz 2