Mapping in rural Hanoi

Context: this diary post

It’s been a month since I posted this diary entry and the progress is not as fast as I’ve hoped. This is literally a one-person operation, and I’ve tried to recruit people from my own Vietnam OSM community, but our community is just way too small to even focus on two different areas. I want to learn the tips and tricks on how to map landuses quickly and efficiently, just like the people in Europe. How can I be just like them?


I have learned most from fellow mappers, by asking “stupid” question on forums!


Well, you are not wrong. But I have completely no idea why the Europeans can map landuses so fast, so I don’t even know what to ask to begin with…

In many European countries, most of the landuse was imported. We still complain a lot about the errors that were made, but it did fill the map. Unmapped territory in my country, Nederland, simply is very, very rare. So we modify a lot, but we seldom start from scratch.

Do you have a particular area you want to map? Is there anything mapped already? Do you have satellite images you can use?

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I’m trying to map the Ba Vì district here: OpenStreetMap, and a portion of it has already been mapped. However, I want to learn how to map more landuses quicker. I’ve tried to find import data for Vietnam, but to no avail.

You will always have to trace the outlines, and that takes lots of time, in all editors. With other stuff such as creating mulipolygons by cutting out pieces of different landuse, you can speed this up a lot by using JOSM. It will take some time to learn it, but that is worth it.
E.g. the PolygonCutout tool can cutout areas from overlapping areas, creating and converting the areas from polygon to multipolygon, vice versa, as needed. That function alone has sped up my landuse-and-water editing by a factor 10.

Landcover is a really long tasks to achieve, above all in a large area.
I mean, in any case, doing it by hand takes a long time.

For hand mapping the fastest way to map landcover is to :

  • Use JOSM
  • Use plugin “utilsplugin2”, “buildings_tools” and “FastDraw”
  • Use shortcut of JOSM (S, A, X, Alt+X, Alt+A, Alt+S, Shift+F of fast draw ! Ctrl+Shift, Ctrl+Alt, F…)

I’m repeating myself, but in any case it takes a long time.

In Europe, there is sometimes open data landcover, but there are often lots of cartographers who have done it by hand. It may seem easier for Europe, but it’s the number of contributors in each european country that makes the difference.

And: don’t try to do large multipolygons. Better split the area into logical smaller areas (polygons), even when they have the same tags. Nothing takes more time than monster multipolygons!

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