Lint is a tool that checks for errors in C code, taking its name from fuzzy fluff that accumulates around us, getting in our way and making us sneeze. Map’s have lint too; misplled tgs, orphan segments and untagged ways all cause problems when people want to use OSM’s data. Maplint does for OSM data what Lint does for C code, it looks at an OSM XML file and generates an error report, which can then be rendered by OSMarender, giving visual clues to the location of rogue data:
The Maplint Layer In InformationFreeway.org
With the extension of the Tiles@Home server to support multiple layers, Maplint reports can now be viewed at InformationFreeway.org. There’s also a plugin for JOSM – JosmLint – that will highlight potential errors whilst you are editing a map, which can be downloaded from here.
Wii have an interesting approach to mapping underground networks developing on the dev mailing list. GPS units are pretty lame underground, and there haven’t been many volunteers to survey the Blackwall Tunnel on foot. A solution being discussed at the moment is to use accelerometers to detect motion and produce a map, specifically the motion sensors that are integrated into the handset of the Nintendo Wii console. The handsets also have integrated Bluetooth, meaning that they could communicate with another device that is connected to a GPS, and through the use of a process like Kalman Filtering, could produce usable results. This is very much a theoretical discussion at the moment – but highlights the inventiveness and resourcefulness of the OSM community. Read more here.
If you want to get hold of raw OSM data to play with, you probably want to get hold of a Plant dump – a weekly snapshot of the OSM database. As the data in OSM grows in size, planet.osm also grows. The last planet.osm was 3.5GB when decompressed – thats a whole load of XML that has to be shipped around the place each week. Jon Burgess has produced a set of tools that produce a diff – a file that contains information about changes to the dataset, so all you have to do is apply the diff to your existing OSM data to have the latest version. Very nice work.
And finally, just when you think you have the whole tagging thing nailed down, something like this happens:
Read more about tagging streets like this one here
By Nick Black