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A lot of shopping center developments have "outlot" stores (often restaurants), and sometimes completely stand-alone buildings will also have parking lots that entirely circle the building. I can see three plausible ways to map this:

  1. Make the parking lot a solid rectangle (or whatever) and map the building as being contained in the parking lot
  2. Make the parking lot shaped like a C-clamp and close that gap with a self-edge (i.e. faking up a 'hole' in the parking lot but keeping it topologically simple), then put the building inside the "hole"
  3. Make the parking lot actually have a hole in it, and put the building inside the hole.

The first is unquestionably the easiest to do, but it is semantically unsatisfying (and also doesn't render very well in some cases). The second is a bit more work, is also a little unsatisfying but at least the building isn't "in" the parking lot. The third I'm not even sure how to do in something like Potlatch, but it's certainly more technically complicated; but semantically it seems to be the best match, if it's technically possible.

What is the received wisdom on this?

asked 28 Oct '12, 19:43

blahedo's gravatar image

accept rate: 50%

Your third option - make a hole in the parking lot and put the building inside the hole - is the correct and commonly used approach. Areas with holes are modelled as multipolygon relations in OSM. It's possible to create these with all of the mainstream editors.

Refer to the Relation:multipolygon wiki page for documentation, including Potlatch examples.

If the parking lot is directly adjacent to the building, you can re-use the building outline as the multipolygon's "inner" member.

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answered 28 Oct '12, 20:33

Tordanik's gravatar image

accept rate: 35%

Ok, cool. Potlatch doesn't seem to be rendering it correctly but the data looks like it's in there (we'll see what Mapnik does with it).

(28 Oct '12, 22:10) blahedo

Third option is the way to go. You can use multipolygon relations for it.

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answered 28 Oct '12, 20:13

RM87's gravatar image

accept rate: 22%

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question asked: 28 Oct '12, 19:43

question was seen: 3,943 times

last updated: 28 Oct '12, 22:10

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum