Wednesday, June 30, 2010

Karura Is Mapped Using OpenStreetMap (OSM)

OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world.
The maps are created using data from portable GPS devices, aerial photography, other free sources or simply from local knowledge. Both rendered images and the vector graphics are available for download under a Creative Commons Attribution-ShareAlike 2.0 licence.

OpenStreetMap was inspired by sites such as Wikipedia; the map display features a prominent 'Edit' tab and a full revision history is maintained. Registered users can upload GPS track logs and edit the vector data using the given editing tools.

Below is an account of the mapping exercise courtesy of Upande

“Having been involved on the technical aspects of project mapKibera last year, it was a  good opportunity for Upande to get involved in some actual ground work, data collection. Last year Mapkibera group led by Mikel Maron, managed to comb Kibera in a combined 5 days. The product was a detailed up to date map of Kibera from entire road network, water points, schools, community centres, to the locals’ favourite pint dens.
Organizers and partners
The Map Kibera team led by Mikel organized a one day mapping part. This May the group, organized by Mikel Maron and Primoz Kovacic was back again for another big cause; mapping one of the only two forests in Nairobi: The Karura Forest.

Mappers this time round consisted of Members of Mapkibera Group, Friends of Karura, who provided the scouts, mapping professionals, mapping enthusiasts, staff from the UN and British Embassy and Molu the scout dog. Security was also well handled with Capt Danny Alexander of the British Army and the Kenyan Forest Service. The exercise brought together a team of almost 35 mappers.

The Forest
Albeit its beauty, the forest only appears in the media, for two reasons:  News of grabbed land or reports of victims dumped after a carjacking incidence.

Not many Nairobians roaming their concrete jungle are aware that quietly at the outskirts spans a scenic (no. of years old) true jungle with an unpolluted river, a water fall and caves.

The Exercise
The party started at 9:30 am at Kenya Forestry Service Headquarters with a brief presentation of the project and mapping techniques (usage of GPS units, OpenStreetMap etc.)

Mapping parties were then divided into seven groups, each covering different sections of the forest. Some interesting like the caves and waterfalls route, to the funny ‘touch me I die’ route; apparently the area is known for the plant species, when touched it ‘plays dead’.

Luckily the group I was in took the caves and waterfall route.
Armed with GPS receivers and digital photos, the groups dispersed one after another to cover the forest. En route to the key points groups picked the GPS points of features of interest e.g. schools, clubs, residential areas etc.

After Party
After the teams were back, the GPS data, tracks and point collected were uploaded to the OSM platform. Mark Iliffe and Primoz giving presentations to the mappers on how to upload and edit collected data using JOSM to the OSM platform. JOSM editor, acronym for Java Open Street Mapping editor, is one of the tools widely used to upload, create and edit data in OSM.

Mark's presentation on using synchronized GPS and Camera to carry out mapping was an eye opener. Apparently if your GPS and Camera clocks are synchronised, it is easier to geo tag photos on JOSM since it matches time photo was taken to that point in time when GPS was tracking. This method ensures a quicker way of collecting data, no stopping, marking waypoint then taking a few photos; if you have ever used the latter method then you understand how much time can be saved with this. Hint: Photos must be descriptive.  If point is a school, take photo of something with the school name. This would greatly help to identify the point once you are editing in JOSM.

When all has been said… when all has been edited and done, we shall have a beautiful, detailed, useful and up to date map of Karura.

I am yet to find a better way of conducting a thorough mapping exercise over a short period of time. By 1600 hours we were already departing. Our task for the day, complete and well done.

Next mapping party?”

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