Mapping Your World

Hosted by Open Data Manchester’ Sam and also Elyse Merriman (who had attended a previous training session), almost all attendees had had little or no experience of OpenStreetMap, with many having never accessed the site before.

There was a good mix of participants too — many from the local university area. One attendee came looking for a potential open source alternative for a project developing a history map of Hulme and Moss Side with their students. Another, a keen scuba diver, was interested in developing an underwater map of certain sites to help scuba diving enthusiasts. Others were just interested in finding out more.

After a short introduction, which included a quick overview of the Mapping Mobility Project that inspired the workshop, we began by asking participants to draw a map of their local area. Whilst a fun icebreaker, it was interesting to start to think about what people had chosen to map, whether they’d used signs and symbols, or sets of colours — and why.

This led nicely into a general overview of maps cartography, in which we looked at different types and functions of maps. Maps show what the map-maker wants us to see, or what they think might be useful. Take this map of the Manchester marathon — it’s recognisable but any superfluous information is left out. It communicates its information in the most direct way possible.

And we discussed how accurate a map needs to be. There are some great examples where an accurate map can be less useful than a warped map. Take the London tube map and its accurate accurate counterpart, for example. Which one would be more useful in navigating the underground?

Some of my favourites include the Manchester music map, which was a great example of how datasets can be visualised creatively — in this instance famous bands and where in greater Manchester they come from.

So maps themselves as a way of visualising data led us nicely into OpenStreetMap.

OpenStreetMap, despite its name, isn’t technically a map — it’s a database of geospatial information. The map we see online is intended to be used to check any data that we are adding to it. Although, of course, people do use it as a regular map (myself included), it’s actually intended as database from which other maps are made.

So we spent some time familiarisng ourselves with the browser, its tagging system and the data it displays. We also looked at some examples maps that have been created using OSM data, such as the European Navigable Waterways map, the Bexhill map, or the 8bit Cities project.

Then it was time for our participants to have a go themselves. Pitched as a beginner’s guide we didn’t go too deep, using only the in-browser ID editor. But after taking attendees through the basics of adding nodes/points, roads/ways and buildings/areas, along with the flexible and open tagging system, they set off exploring the map and beginning to make their first addition and edits. The only edits that were saved where those that we knew to be true — so mainly missing buildings and roads, added using the aerial imagery in browser.

We made sure that they were aware and followed some simple rules of thumb. These included:

• to be as accurate as possible ie not to map from memory.
• only map what you can see. So photographs are OK, as is adding any unmapping roads or buildings from the aerial photography in the browser.
• Map what is on the ground — so if a street name on the sign is different from what is on a council database, map the name on the sign.
• Never steal from another source — ie don’t just copy something from another map! Why? You’re probably breaking copyright, but that map may also be inaccurate…