Beginner's Guide to TINs, DEMs and Contours Using QGIS

Introduction and Intent

There are two purposes of this tutorial, the first being to introduce new Geographic Information Systems (GIS) users to the uses of Triangular Irregular Networks (TINs), Digital Elevation Models (DEMs) and traditional cartographic contour lines. The second objective of this tutorial is to show the processes that users can follow to create, manipulate and use these three datatypes within the QGIS open source software. The three aforementioned datatypes are related in one key way, they all are different means of representing elevation data. They differ in the ways they accomplish this and the types of data they use. These distinctions are discussed in the Vector vs Raster section of this tutorial.

QGIS

QGIS is an open source, free Geographic Information System that lets users display and modify geometric datasets. This means that data that incorporates any sort of geographic positioning, such as incorporating coordinate points into a spread sheet, can be used to create data that exists in a 2 dimensional space. This is a very powerful tool for any user that wants to communicate spatial information to a client, pier or superior. Skills in the use of GIS’s like QGIS increase the user’s ability to disseminate information easily and are in demand in fields ranging from transport, mineral exploration and exploitation, construction and far more.

Downloading QGIS

For the purposes of this tutorial, you will have to download a copy of QGIS for the download portal here. There will be three versions of QGIS that are accessible here, each with a 32 and 64 bit version. The version we want is “QGIS Standalone Installer Version 2.18 (64 bit)” as seen in Figure 1.