Invalid polygons

[maning]

With turf.area, negative values means that the polygon has invalid geometry like crossing ways. Let's use this to detect invalid polygons.

[maning]

@geohacker @Rub21

[Rub21]

@maning .- what are the invalid polygons?

[maning]

@Rub21, for example, in this building shape analysis repo we calculate polygon area in one of the metrics. Any polygon we detect that has negative numbers is an invalid polygon. For example, this building.

As a start, we can run this linter for all buildings and mark as invalid poly if it has negative area value.

[Rub21]

@maning this is nice figured out, let's add on osmlit.

[Rub21]

I saw here the Tilereduce procesor(https://github.com/mapbox/osm-building-shapes) made by @geohacker , Maybe he is the right person to add this on osmlint.

[geohacker]

@Rub21 was thinking about this the other day! I can add this, will get you to look over once I push the code.

[maning]

@geohacker @Rub21 @arunasank Can we do this? Context here: https://github.com/osmlab/labuildings/issues/92#issuecomment-222731623