Matching visual hierarchy to information hierarchy

If you want your map to be successful in portraying it’s story or message then it’s important to start with user requirements.

It’s important to fully understand the users requirements in terms of information hierarchy and match the visual hierarchy accordingly – that is to say that they will notice the MOST important information first and the LEAST, last. In cartography this is often referred to as figure/ground.

At work recently I was involved in the cartographic design of one of our latest apps – here is a blog post explaining our pie chart clustering solution that forms part of it.

The app displays point features on a map and groups them into four discrete categories. In this post I will explain my thought-processes and reasoning for choosing the colours that I did; matching the visual hierarchy to the information hierarchy.

The data could be categorised and styled in various different ways but the user in this instance is MOST interested in whether or not the features are A or B. They can also be either 1 or 2 but this information is of SECONDARY importance. It is also MORE important to highlight 1 before 2. Therefore the user’s information hierarchy looks like this:

The user’s information hierarchy

Although A1 and B1 have equal importance they need to be distinguishable from each other and have more visual importance than A2 and B2.

Here are the colours that I chose:

Matching colours to the information hierarchy

My first consideration was choosing two colours that are easily distinguishable and for this purpose also accessible – meaning they are discernible to those with colour vision deficiencies (CVD). For this I used the preview modes in Adobe Illustrator which simulate different CVD but there are many tools available (QGIS has this function which is cool for map-makers). So, this gave me the colours for A and B.

Previewing the colours to ensure accessibility for CVD

I then used the saturation and brightness levels to separate the 1’s from the 2’s. This gave me the corresponding colours I required whilst making them appear LESS visually important.

In the app we then applied these colours to simple circle symbols and use an 15% transparency. We have also applied a thin outline to the circle symbols to subtly lift them from the basemap.


I would highly recommend Colorbrewer for grabbing colour palettes and I have personally found this resource very useful recently. The colours I have used above are from the Material palette.

This is just one example of the MANY thought processes that cartographic designers go through to ensure that our maps are successful in meeting their user requirements.


Rewarding excellence in cartographic design

Ordnance Survey are proud members of The British Cartographic Society (BCS) and have been sponsoring the society’s annual symposium for many years. Every year the CartoDesign team ensure that OS has a strong presence at the event, from providing an exhibition stand to presenting and hosting workshops.

OS have also provided an award since 2005 which until last year was titled ‘The Ordnance Survey MasterMap Award for Better Mapping’ and aimed to “encourage innovative and stimulating map products derived from, and composed mainly of, Ordnance Survey’s MasterMap data.”

This award ran for 8 successful years in which time a diverse range of entries were rewarded.

This year welcomes a change to the format of the Ordnance Survey Award. 2013 is the debut year for ‘ The OS OpenData Award‘ that seeks “to encourage excellence in cartographic design and the innovative and exciting use of OS OpenData.”

Enter HERE before the end of July.

This award is open to anyone, anywhere, whether or not you are a member of BCS. All you need to do is enter a map that is comprised of at least one OS OpenData product and there is an obvious focus on cartographic design.

As an extra incentive the winner will receive an Apple iPad! So…what are you waiting for? Go HERE to grab your free-to-use data and make a cool mapsterpiece!

To see examples of OS OpenData in use take a look at the showcase HERE

I am a big fan of the iCoast basemap which is made using OS VectorMap District and a unique colour palette…

iCoast - Explore the Dorset coast
iCoast – Explore the Dorset coast

Sharing some great tutorials

I want to share some of the great tutorials that I have come across from fellow map makers on the web. I haven’t necessarily worked through all of these but from just reading them have either learnt new tips and tricks or just been really impressed and inspired.

Using MapBox and TileMill with OS OpenData by my friend and colleague Jack Harrison (@jhrrsn)

Glowing Hot Maps – QGIS Meets GIMP by Anita Graser aka Underdark (@underdarkGIS)

Global Connectivity Revisited: mapping out 58,288 flight routes by Michael Markieta aka (@MichaelMarkieta)

Styling data in TileMill by MapBox (@MapBox) – this is just one section of the fantastic TileMill documentation

Point Stacker example by OpenGeo (@OpenGeo)

And here is a map I made by following Michael Markieta’s fantastic tutorial on mapping OpenFlights data…

A world connected
A world connected