The art of presenting complex spatial data simply

Emma explains the trials and tribulations of creating easy to understand maps from complex spatial databases.

Emma Burge is our resident map nerd/GIS Analyst and works in our Compliance team. She has a Postgraduate Diploma in Geospatial Science and has been working in the GIS field for three years. She joined the EPA last year to work on improving the our geospatial capabilities.

16 July 2020

Maps are generally presented to us as fact. However, more often than not they are stories crafted by the cartographer to influence a viewer’s interpretation of the topic. Since maps have existed, they have been used to manipulate and change how the public views the world. Digital map makers need to create consumable yet complex spatial data while not jeopardising the accuracy of the information itself.

In my work as a GIS Analyst with the Environmental Protection Authority, I regularly make difficult decisions about balancing the information I include in maps, to make sure they paint an accurate picture of the world around us.

Getting the GIS-t of GIS

A Geographic Information System (GIS) can be most easily understood as Google Maps on steroids: the act of gathering, managing, analysing and presenting spatial data using a mapping-specific software. It’s the modern form of the ancient art of cartography, but now we can make a computer do the hard stuff for us.

To me, it’s a fun way to combine nerdy skills (like database management) with creative skills (choosing fun colours and symbols).

(Topo)Logical decision making: Selecting information to create an accurate, readable map

As much as I would love to, it’s impossible to make a map which completely represents this complex world we live in. At the EPA, we have over 150 layers of data which might sound like a lot, but these layers of data represent a mere fraction of the possible information we could use!

And herein lies the challenge of the GIS cartographer: like a botanist curating the plants in their garden, the GIS cartographer must carefully curate (select and refine) the layers in the map to give it meaning. 

A multi-layered map of New Zealand showing a number of different types of data and topographical information

Figure 1: A multi-layered map of New Zealand showing a number of different types of data and topographical information

This map of of New Zealand demonstrates how including too much information on a map can reduce the value and readability. Instead we have to select what information we include to give the most accurate but readable map.

Including or excluding information is a point where the cartographer has the opportunity to influence another person's understanding of the world. We have to decide whether the loss of information resulting from the exclusion of a layer of information outweighs the need to present a map which is readable.

Figure 2 below shows an example of a map which demonstrates proper cartographic techniques. The map models an area off the coast of Taranaki to show the location of offshore oil platforms in New Zealand’s Exclusive Economic Zone (EEZ). To effectively display this in a readable manner, I had to make decisions about what layers to include.

There are thousands of layers of spatial data provided by organisations across New Zealand, showing everything from socioeconomic trends in major cities to nitrate levels in rivers. For this map of the locations of offshore platforms in our EEZ, there’s a lots of information we don’t need to include (say socioeconomic trends and nitrate levels in rivers).

There’s also information that we need to include (the location of platforms), and also information we include to provide important context to the map (petroleum permit areas and the territorial authority boundary).

In making these decisions about what to include or exclude, I have created a map which presents this area in a valuable way.

A map of New Zealand focusing on a small section of the EEZ.

Figure 2: An example of a map which uses proper cartographic techniques to display information in a meaningful and easy to understand way.

Projecting our way of life: Curating the world view from the EPA perspective

At the EPA, we use GIS every day to monitor and better understand the environmental impacts of things going on Aotearoa’s territory. Our functions are so diverse; protecting not just New Zealand’s landmass, but 5.8 million square kilometres of ocean as well.

Some teams want to understand soil composition and topography when assessing pesticides, while others want to monitor rocket launches! This diversity of function offers so many unique opportunities and challenges to the EPA.

GIS makes it easier to understand these and present them to ourselves and others in a way which is easy to understand.