OpenStreetMap

We need to look at consistency of coverage in the Philippines. Let's target LOD1 first.

Posted by maning on 20 February 2014 in English (English)

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).

Visayas road gaps after Yolanda crisis mapping

  • 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).

Marikina Cainta border

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 city node 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, primary roads);
  • Move previously imported place=island nodes 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.

P. S. As I am drafting this diary I was reminded by two other related post by: Harry and Severin which shares somewhat similar sentiments.

Location: Kayamanan Compound, Magallanes, District I, Makati, Metro Manila, 1232, Philippines

Comment from _al on 20 February 2014 at 14:11

Any coordinates where this is located?

/al

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Comment from maning on 20 February 2014 at 14:41

@/al, I updated the entry for the location of the images. If that is what you mean.

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Comment from Warin61 on 27 February 2014 at 00:40

I've been mapping well outside my area! Basically the other side of the world. My nation has an interest there and I think there are details there that would be of use/interest. So I've added them. There is still some work for me to do ther, but I'm waiting on - copyright permission, time to read a book.

'We' as mappers have a desire to map things that 'we' are interested in, have knowledge of. So I don't think OSM is going to get consistency but rather a patchwork of interesting places, not a bad thing to have :). While it would be 'nice to have' a consistent map, the areas that don't get used would be a waste of effort. And mapping those areas by someone who has not interest in them may well turn them off OSM. So while a nice idea it may not be easy to achieve, and I'd certainly not try to make volunteers do something they 'd rather not do. The more people involved though the better - each of us has different interests and so all areas may well be mapped eventually.

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