OpenStreetMap 開放街圖
In order to better understand the villages in west africa fighting the ebola outbreak currently occurring there, it would be good to have better population data for the towns. One way to do this is to measure the number of buildings per square mile in a typical vilage and then just map a “perimeter” residential landuse area around a village and then work out how many buildings there should be based on the size of the area.
I have been experimenting with this a bit using the data mapped in OSM. As of the time I made this dataset we had 43 small villages in this area that had all of their buildings mapped, as well as a footprint to measure the area. I calculated an average building density of 0.00418 buildings per square meter. Then using this figure I pretended I didn’t know the number of buildings in the town and then re-computed how many there should likely be based on the area. The results are in the graph below, and look quite good.
If the method worked perfectly they should fall exactly on a line with the predicted number being exactly equal to the actual number. Of course in reality the prediction is not perfect but it does look pretty good.
討論
由 Mark_Cupitt 於 2014年03月29日 05時01分 發表的評論
This is Great Andrew, very nice. Would there be some value in the Tharpaker Effort as well? We could possible add a tag to the landuse=residential with a building count, for example, dwellings=12
Cheers
Mark C
由 AndrewBuck 於 2014年03月29日 13時25分 發表的評論
Yes it would be possible. It is important if you do this though to make sure all the landuse=residential areas are drawn around the villages in a consistent manner. Have a look at how Pierre and I do the borders around the villages in the southwest region there and that should give you a good idea how to do the borders to keep it consistent. Since the bulk of our analysis is based on the area of the village, making that polygon fit nicely is very important.
For the test villages I don’t tag the number on the area I just map the actual buildings and huts in OSM and then use QGIS to count how many buildings are in each residential area. I can help you get started with building tools if you are interested in mapping the test villages to seed the density calculations.
-AndrewBuck
由 Mark_Cupitt 於 2014年03月31日 03時48分 發表的評論
Hi Andrew, Yes, that would be good. I use QGis, but mostly for Geo-referencing and general GDAL raster manipulations. (Analysis is not my strong point) I will have a look at what you guys are doing and then see if we can do a test tile to see how it works
I would be interested to try and tag the permanent and transient dwellings and see if we can get some useful data from that, but will need to research the lifestyle a bit more on what those isolated huts are actually for.
Cheers
Mark C