[Imports] Large scale building edits in Fiwila, Zambia

[Rory McCann]

On 11/06/17 23:17, Bjoern Hassler wrote:
> Of course. However, it was a significant effort to mark the 3200 
> buildings, and it's impossible for me to manually trace 3200
> buildings.

I don't think tracing 3,200 buildings is impossible. It's a fair amount
of work, but it can be done.

With JOSM, and a few plugins, you can make it much easier. You'll need
the todo, building_tools, utilsplugin2 and continousDownload plugins.

Once those plugins are installed, open up the advanced preferences and
disable 'default-on' for continuosDownload ( set
plugin.continuos_download.active_default to false), reduce the wait time
(plugin.continuos_download.wait_time 10), and for this task you should
turn off default tags for the building tools (buildings_tools.tags [])

When you've done that, this is how you remap all the buildings:

1) Use Overpass Turbo to find the nodes with building tag and export
them into JOSM. This Overpass query will find them:

     [out:xml][timeout:2500];(node["building"]({{bbox}}););out 
meta;>;out meta qt;

2) Select all nodes (Control-A) and add them to the TODO-list

3) Double click on the topmost entry in the todo list, to zoom into one,
and download that area. Turn on some aerial imagery. Turn on "continuous
download (File menu).

4) press B to map the current building as a rectangle, or draw a
triangle, and press Shit-O to create a circle.

5) press S, then select the original point and shift left click to
select the new building, and press Control-Shift-G (replace geometry) to
move the tags over to the way, and remove the old node

6) Press ] to go to the next node. Go back to step 4.

This is a fast an quick way to remap buildings from aerial imagery.

I saw the discussion on the HOT list about buildings mapped as nodes,
and started to remap and clean up the instances in Ireland. If you keep
at them, you can do it! If you recruit one more person, you'll half your
work, etc.

 From looking at Ireland, I've noticed that there are many nodes with the
building tag which are badly placed, or there's one node for many
buildings, or no building at all. If you manually look at them, you'll
get better results than a script.

I hope that helps,

Rory