For the past several months, OSM Philippine data is getting noticed by a good number of people and organizations. This is in part because of our crisis mapping in response to Typhoon Yolanda/Haiyan but, I also think the data is now in a usable state in many areas thanks to the dedication of local mappers.
As I look around the map, there is obviously a lot of inconsistency in data coverage. Some are mapped up to the individual buildings while others just a
place=town node and nothing else.
Two things I consider to be a factor of this situation:
- Most mapping are based on satellite imagery. In the case of my country, while imagery is available over large areas, many areas still don't have hi-res imagery. This makes mapping "stop" at the edges of the imagery. The image below shows roads digitized during Yolanda mapping (map).
- Most local mappers are too focused on improving their own patch. This isn't really bad since you should really map areas you are familiar with but, this leaves behind adjacent areas looking bare and the coverage uneven. Even I am a victim of this micro detail mapping. Just look at Marikina (my mapping patch) on the left and Cainta on the right (map).
I still think we should map in detail our own local area, but we should also keep in mind to look beyond our patch to produce a good level of consistency and evenness of coverage.
Eugene outlined this level of detail concept a few years back. In the document, he proposed 7 LODs based on the following parameters:
- Scale / zoom
- Spatial accuracy
- Completion unit
Re-reading this document, I feel that the current Philippine data isn't even on the first level. So this year, I plan to incrementally work on reaching LOD 1 (while continuously improving my own patch of course!) focusing on the following:
- Check whether all cities and municipalities have at least a
place=town or citynode located within the town/city center;
- Check whether all national roads are mapped and connected to the cities and municipalities (in OSM tagging, the
highway=motorway, trunk, primaryroads);
- Move previously imported
place=islandnodes to each way/polygon (working on this now);
- Map major rivers (
waterway=river) and other large water bodies;
- Fix relations of existing provincial boundaries.
Definitely a big task, but we can always work together.