Learn the basics of Cartographic Principles

Introduction

One of the main and easiest to understand parts of my role as a GIS officer here at Proterra Group is the production of maps that go into reports to easily display information. While it may seem a simple task there is actually a lot of forethought that goes into the preparation of a map and this can be the difference between a easy to understand way to convey information and something that is almost illegible.

Map Design

People read a map because they want to know where something is. With this in mind, there are a few features of a map that must be included.

• North Arrow – An arrow that points towards North based on the orientation of the map. For the majority of maps this is just the same orientation of the page however there are cases when a different orientation is useful (when mapping a road corridor for example).
• Scale Bar/Label – A bar or notation of the level of zoom the map is at. This also is useful for getting accurate measurement data from your map.
• Legend – A legend displays what layers are on the map and what they look like. Having a legend allows you to have multiple layers of the same type (lines, points or polygons) on one map while being able to differentiate between them easily.
• Map Credits – This is a simple acknowledgement of who created the map, who created the data and the date the data was from. This is important not only for copyright issues but also for legitimising your data.

The Importance of Colour

One of the main issues the beginner GIS analysts and officers run into when designing maps is picking the right colours for different features. While this may sound trivial, picking the wrong colours can leave your readers confused and lead them to misinterpreting the data you present. The first thing you must consider is that your colours do not look too similar to one another. While they may look different when you are creating the map, they may not have the same contrast when printed or rendered by different computers. Similarly certain colours are associated with different features. For example, the colour associates with water is blue so for someone having a cursory glance at your map will see blue and assume it has something to do with water whereas if you coloured a river line feature red that same person would most likely not realise what the feature is.

Handy Hints and Tricks

Some other things to consider include

• How your features are labelled.
• Making sure features and labels don’t overlap covering the data you want to display.
• What basemap you use and how it interacts with your data.
• Title blocks, tables, images that can be added.
• The drawing of features such as arrows and shapes onto your map.
• Using patterns, hatching and gradients to differentiate data along with colour to be inclusive for people with sensory issues such as color blindness.

And remember, maps are a great way to visualise and disseminate your data to a wide audience of people in a short period of time.

If you have any questions about how to best to do this or want anymore information, feel free to contact me via the below contact form or at David.Mitchell@proterragroup.com.au