Time to rethink the design process: colour blindness and maps

There is a genetic disorder that affects up to 10% of men and about 0.5% of women. It impacts on their daily lives, often making the simple everyday tasks difficult and crushes the dreams of budding pilots and wannabe coast guards everywhere. Yes, it’s colour blindness. But for something that is experienced by a sizable minority of the population, colour blindness seems to play a relatively small role in the design process. Think weather forecasts, snooker and, yes, maps. The traditional rainbow of cartographic colours – greens for vegetation, reds for main roads and footpaths, and blue for motorways and rivers – can become indistinguishable, therefore making map reading really difficult

It’s an issue that has been looked into by others, but up until recently it’s not something that we have been able to take into account when producing either our paper maps or our data. But all that has changed in recent times. With the launch of customisable data, like OS VectorMap Local, the user has far greater flexibility around how mapping is displayed and styled.

Colour blindness is the result of a deficiency of the specialised ‘cone’ cells in the eye that make colour vision possible. It is the most common genetic disorder among humans, with hundreds of thousands of people unable to tell the difference between reds and greens. Instead these colours appear as shades of grey or brown, making it difficulty to interpret colour-coded features. The Product and Cartographic Design teams here at Ordnance Survey have been working on colour schemes that can counteract this effect.

One of the styling exercises specifically for the colour blind, looks strange as it uses completely different colours for familiar map features. The result is a combination of purples, browns and oranges.

Simon Duquénoy, Technical Product Manager says:

“Cartography is a fine art, but the colours that have become so familiar to most of us are actually among the worst possible choices for those with colour blindness. Because of the technical developments in mapping data, we’ve been experimenting looking at how we can be more colour-blind friendly in our designs and colour choices.”

We are now developing a new colour palette for mapping that will work whether you are colour blind or not. This has been designed using software that can emulate the more extreme forms of the impairment. It has also been tested with a group of colour blind test pilots drawn from Ordnance Survey staff.While initially using the science of colour differentiation, we soon ran into familiarity issues – ‘Why is the motorway red ?’ asked the test group for example. Due to this we revised the colour style to make motorways blue again, but using a different shade to provide the contrast with other colours that is so important to the colour blind.

This is a major leap forward in cartographic design and leads us from thinking about specific accessibility for those with hidden impairments, to maps that are really usable by everyone.

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15 Responses

  1. Denis Payne

    Excellent news! It’s really important to have something that works for all – but it’s also really important to spread the wider understanding of the problem, and the possible approaches to minimise the problems.

    Far too many people producing maps (both base maps and material based on those) don’t understand what they are doing using red and green …..

  2. Hi Denis. Thanks for commenting and I’m pleased that you’re enthusiastic. We’ll keep you up to date on the project as it develops but is there anything else you’d like to see us cover on the blog?

  3. Rob

    Interesting. Whenever I look at a map I have an opinion about the design, but (not being colour blind myself) this aspect would never have occurred to me.
    However, I picture the future of mapping as being online, with walkers and cyclists following the GPS trend amongst vehicle users – or, at the least, printing their own maps from online applications. At that point, I would imagine the traditional colour palette becomes simply a default setting and users have the option to select colours based around their own preferences – be that to overcome colour blindness or simply because they want a map with purple rivers…

  4. When I was interviewed for a job as draughtsman at Maybush back in 1973, I was rejected because I failed the colour blindness test. I know I’m not, and I managed to persuade the interview board to test me again using map material (a surveyors MSD as it turned out to be) and I passed 100% – to the amazement of the board. I got the job! Maybe the test should be carried out in maps in future! But it’s good to read about the OS working on better colour rendering for all folks.

    1. Hi Steve. Thanks for commenting – I didn’t realise that OS used to test for colour blindness! I’m glad you like the sound of what we’re working on, but as someone without a surveying background, could you explain what you mean by MSD?! 🙂

  5. Jon

    The OS OpenData initiative provides OS Street View but unfortunately, despite claims in the documentation that the colours may be customised, anti-aliasing prevents the colours from being sensibly changed. I’d love to use this data in an accessible product but it seems impossible to do so. Does the OS have any plans to release Street View in vector form, or in an alternative format that does not have smoothed edges for lines and text?

  6. Jon

    Hi Paul; thanks for your reply. I am using VectorMap District as well, but it doesn’t have the level of detail required for easy navigation of pedestrial areas like Central London.

    The OS Street View site goes as far as to say this, concerning colours:

    “OS Street View is supplied in colour and has the additional feature of an editable colour palette that enables users to be able to change the colours of features to match their own specific requirements.”

    I think this is inaccurate, to say the least… I was looking to customise the colours but was quite disappointed when I inspected the data in detail.

    1. Hi Jon, I’ve spoken with our product manager for OS Street View and you’re quite right. While changing the colours is possible it would be a big job, so with that in mind we’re going to change the product information. Thanks for your feedback, it really is worth giving and we will always make changes where we can.

  7. Jon

    Hi Paul. The documentation has not changed on the specification page: although black and white is now mentioned, there’s still the reference to the customisable colour palette. Just thought I’d point this out.

  8. Hi Paul. I read about the new OS colour palette in the weekend edition of the Financial Times. The article claimed that OS had developed a more radical recolouring but that this was rejected by the focus group, would it be possible for you to post an image of the rejected colour scheme?

  9. Hi Paul. Wow!, I can see why you took on board the focus group’s view and toned down the final results. I look forward to seeing some of the later designs. Thanks for posting.

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