Looking for known, well-mapped areas in Botswana

[rossbernet]

The Azavea team is building a model that will produce population estimates based on building densities from OSM. This will be compared to the worldpop raster to find areas that are incompletely mapped.

To train the model, it will be necessary to provide locations that are known to be accurately mapped. We are starting the efforts in Botswana, so ideally locations in Botswana, but countries with similar land use or population distributions would work. A range of settlement patterns would be useful: rural <> urban.

@geohacker @jpolchlo @moradology @kamicut

[awright]

If understanding correctly, this relates to #5 AOI scale? Apologies if you have to break it down for me.

[rossbernet]

My impression is that #5 is concerned with prioritizing starting locations and determining the scale of analysis.

This issue is concerned with finding training data that can be used to train a model with locations that are predetermined to be accurately mapped. We would like to be able to say, "this is an example of 100m x 100m area or this zoom level 12 tile is known to have buildings that have been accurately and completely mapped" And ideally we would have several different areas representing different settlement types. I.e. an example of a fully mapped rural area, small town, bigger city.

[PaulUithol]

As we'll be ground truthing a lot of data shortly in Botswana - we're currently doing a verification pass over Chobe district, https://tasks.hotosm.org/project/4317

[geohacker]

Thank you for the ticket @rossbernet! I'm tagging @rub21 - he might have some ideas of locations that are worth looking.

[smit1678]

The malaria map viz might help or osm-analytics:

https://www.mapbox.com/malaria-mapping/#5.21/-18.390/25.539 http://osm-analytics.org/#/

But for #5 we'll prob hone in on some other districts in Zim or Cambodia where there is well mapped areas.

[ridixcr]

With a quick search in Africa I could detect, good places with OSM coverage and DigitalGlobe Standard.

*	Link	Digital Globe	OSM Data
Niamey	https://www.openstreetmap.org/#map=14/13.5340/2.1157	Good Image	Medium
Dosso	https://www.openstreetmap.org/#map=15/13.0442/3.2002	Good Image	Medium
Gasau	https://www.openstreetmap.org/#map=14/12.1775/6.6819	Good Image	Low
Kano	https://www.openstreetmap.org/#map=13/11.9848/8.5537	Good Image	Low
Namiya	https://www.openstreetmap.org/#map=13/10.5000/7.4247	Good Image	Low

the data and the image are not aligned because they worked with Bing.

cc. @Rub21 @geohacker

[jpolchlo]

I've made a viewer that can be used to pick out tiles from the set of zoom 12 vectortiles over Africa. It's described in this PR: https://github.com/azavea/hot-osm-population/pull/1. This may be useful to generate lists of tiles for the model fit. It does require the manual input of a Mapbox API key here: https://github.com/azavea/hot-osm-population/blob/master/view/index.html#L101.

Perhaps it will be useful?

[kamicut]

Thanks @jpolchlo! @smit1678 could we perhaps add HOT's Mapbox key and deploy this to s3?

[smit1678]

👍 sent via Slack

[jpolchlo]

FYI: found a small bug. Fixed it in azavea/hot-osm-population#2. If you've pulled the source, please re-get it.

[jpolchlo]

For frame of reference, the above simple viewer suggests a fairly manual process:

1. Load the web page.
2. Scroll around looking for areas of good coverage.
3. Click on the tile, write down the index
4. Repeat until there are enough samples.

Mapbox gl is also a bit glitchy when you don't have a complete pyramid of vectortiles. The sample implementation draws from vector tiles that Azavea produced, which start at zoom 12 and go up to zoom 15, so vector data might not appear until you zoom in far enough. Might be worth switching over to the Mapbox QA tiles for display.

The feeling is that there has to be a better way. I just mocked something out that worked, but isn't apt for general consumption. @geohacker: @kamicut suggested that I ask you if you've got suggestions for improving this.

[echeipesh]

Ended up generating the training set in QGIS by overlaying WorldPop/OSM/MapBox layers. More info here: https://github.com/azavea/hot-osm-population/blob/de930c3879690efd28200cae71ec9b92e9faf8ce/README.md