Most maps are static representations of a geographical snapshot in time but the world changes constantly, especially in fast-moving situations such as wars or natural disasters - something I recently explored in a recent documentary for BBC Radio 4, Mapping the Void.
One group of people rising to the challenge are the million or so volunteers behind Open Street Map (OSM). They're dedicated to creating an open-source, accurate and licence-free map of the entire world that anyone can edit and use.
When a catastrophic earthquake hit Haiti in 2010, a group of OSM volunteers used their skills to help the stricken nation. Previously, it had been one of the worst-mapped countries in the world. Yet after just three weeks, 640 mappers had made more than a million edits around the central third of Haiti, using a combination of satellite imaging and information from people on the ground.
Their efforts are beautifully visualised in this video, showing the flurry of detailing that appeared in a matter of days. It was invaluable to the aid agencies responding to the humanitarian crisis in the wake of the quake, and remains the most accurate map of Haiti to this day.
Mapping Haiti
Meanwhile at Tufts University in Boston, student Patrick Meier was watching the disaster unfold, knowing that his wife and friends were somewhere in the country's capital, Port-au-Prince. Moved by the need to do something - anything - to help, he began to plot tweets coming from Haiti onto a map.
It soon became clear that there was more information than Patrick could cope with, so he recruited fellow students to help. Creole speakers around the world also got involved, translating tweets and text messages.
The result was a map used by international aid responders to identify people in need across Haiti, described by the U.S. Federal Emergency Management Agency (FEMA) as "the most comprehensive and up-to-date map available to the humanitarian community".
Since then, Patrick and his Digital Humanitarian Network - formed in the wake of the Haiti response - has led volunteer mappers as they chart other crises, including the recent typhoon in the Philippines.
Mapping the world
Crowd-sourced mapping doesn't have to be done on a country-wide scale, or in response to a major disaster. In Kibera, Kenya's largest slum, volunteer mappers are bringing order to chaos by plotting the shifting streets. What started as an effort to map basic services like toilet blocks, schools and pharmacies onto an area that was previously denoted as forest has now led to the settlement having its own video news channel.
Just as Patrick Meier found in his Boston dorm room, while one man can only do so much, a crowd of willing hands can achieve a whole lot more. Justine McKinnon leads CrisisMappers UK, a group of around 250 volunteers that source and plot information about international as well as local situations. When I went to meet her at her home in Hayling Island, the UK was being battered by high winds and rain, leading to disruption and flooding.
Justine showed me how to use a newly-developed artificial intelligence system to trawl Twitter for messages and plot them onto a map. She also showed me MicroMappers - a crowd-sourcing platform that's being developed to analyse the usefulness of information in tweets and texts from disaster zones.
The thrill I felt from marking the closure of the Humber Bridge due to high winds quickly paled when she showed me the maps she worked on following Typhoon Haiyan's trail of destruction across the Philippines in December 2013.
Are they any use?
At the moment, there isn't much hard data available on the usefulness of volunteer maps in the wake of a crisis. However, there are a number of anecdotal reports, and aid agencies like the Red Cross are taking the technology seriously, suggesting they do find it useful.
One area that still needs to be thrashed out is the tussle between volunteer-led mapping with open-source software - which is cheap but can be unreliable - versus more stable commercial platforms fed by paid information-gatherers on the ground in the disaster zone.
Talking to people like Patrick, Justine and the OSM volunteers, what comes across so clearly is their passion to use their digital skills to help people in desperate situations. Although there are issues with this kind of crisis response - concerns about accuracy, security and software stability being just three - they all feel it's better to be doing something practical to help.
Mapping the Void was broadcast on BBC Radio 4 in February 2014. Listen again on BBC iPlayer