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mapbox / mapnik-vector-tile

Mapnik implemention of Mapbox Vector Tile specification
BSD 3-Clause "New" or "Revised" License
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Broken tiles #188

Closed jakepruitt closed 8 years ago

jakepruitt commented 8 years ago

After rendering some terrain data vector-tiles with the new v2 specification, found some tiles had invalid geometries, which were causing large deviations between the expected area and the area calculated by earcut.

Tile Layer Deviation Validity failures z7 tile
12,2244,1715 contour 253.64864864864865 interior_rings_outside 70,53
13,4817,4321 contour 241.72 interior_rings_outside 75,67
14,9843,8746 contour 158 interior_rings_outside 76,68
11,1556,777 contour 73 interior_rings_outside 97,48
12,3233,1464 contour 31.794736842105262 interior_rings_outside 101,45
12,1988,1777 contour 27.457142857142856 interior_rings_outside 62,55
14,5587,8896 contour 13.777889723392562 interior_rings_outside 43,69
11,1492,861 contour 10.678260869565218 self_intersections_method_t 93,53

Right now investigating the [14,9843,8746] tile. Still difficult to get a consistent source to test mapnik-vector-tile, since these tiles were generated from a postgis table that takes a while to load up with terrain data.

cc/ @flippmoke @mourner

flippmoke commented 8 years ago

I think that most of the tiles with interior_rings_outside will be fixed by the latest update to the clipper that was made and commited. The only remaining one that is questionable is the self_intersections_method_t. Here is the geojson for that layer: https://gist.github.com/flippmoke/3ea6fd48c7ab813d22e6

flippmoke commented 8 years ago

The self intersection tile 11,1492,861 was corrected as well by the clipper fix, closing this for now.