JOSM : tool to auto-generate areas out of surrounding lines?

I generate lots of landuse polygons.
Landuse polygons normally are surrounded by a complete closed set of lines (e.g. highways, paths, other polygons…)

Is there any JOSM plugin to automatically generate a new polygon inside such a set of lines by duplicating and connecting all surrounding nodes with minimum permissible distance (to prevent “double point use”)?

Tx. Andreas

I don’t know any such tool. I’d use these steps:

  1. select the ways
  2. enable parallel mode (Shift+P) and create copy
  3. remove tags of the parralel copy
  4. either combine the ways with C or create a multipolygon with Ctrl+B
  5. check that the geomatry matches the area
  6. add tags

sorry, but this will not do the task…

  • the surrounding lines are normally much longer than the short pieces limiting the land area to be filled. For example if you wnat to generate a “farmland” area anjacent to a forrresst, the forest is often alare large multipolygon → coppying copies the whole objects
  • after cropping, the resulting polygon ist same size as the source lines. To fill in an area however, the polygon should be smaller. So you must adjust many points manualy
    → So the overall the time needed and error probability ist heighter than in manually creating athe polygon, possibly using a copy of only one side line with especially many points

The parallel mode makes this easy. When you drag a set of lines they are automatically scaled.

I tried again, ans succeeded now:
There was a important hint missing: the parallel mode /scaling relative to polygon center works only with “simple, unbranched” polygons, so you must copy, crop and combine first, only then scaling works…

It is not the “semiautomatic” solution I imagine, but in some cases useful, I will try it out

Thanks Andreas

tried some times, but time effort is always higher than creating polygon manually, so no real improvement

And do you still think that a plugin could improve the work flow?

I think so, because generating such polygons is a everyday task for generating landuse polygons.
If there is no exuisting solution, i might post as suggestion for such tool.
I the end, it is “not much more” than the “flood fill” tool of pixel graphixs programs.

  • from a point klicked, determine all surrounding line/polygon segments → if line is not closed, abort
  • determine all points conteining to this lines
  • connect and copy all this points
  • determine centre oft resulting polygon
  • change position of each point relatively to polygon center for distance x = scale area as in parallel mode
  • display polygo for further editing

I know, the problems arise in detail work, e.g. what if center of area lies outside of area in case of partly concave polygons…
I think it would accelerate creating landuse polygons a lot…