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I am trying to switch my current map-based application from geojson type source to vector tile source. As a proof of concept, I did a small experiment to visually compare the features drawn from geojson source vs vector source. Features drawn from vector source are geometrically different than that of geojson.

Especially polygon geometries have a skew effect like shown below where features with black boundary are drawn from geojson source and blue one are from vector tile source

enter image description here

I need an exact precised tile-set at this point to succeed with my poc. I am using following tippecanoe command to create these tiles :

tippecanoe --minimum-zoom=5 -s EPSG:3857 --full-detail=20 --low-detail=18 --detect-longitude-wraparound --no-tiny-polygon-reduction --no-tile-size-limit --no-line-simplification --no-tile-compression --output-to-directory 'MT C Parcels' -l 'MT Parcels' /home/ubuntu/data/FWv2-data/data/geojson/1.geojson

Guessing it is a projection related issue, I tried couple of different projections with no success. How do I configure this command so that I can get exact tiles to be drawn as if it were from geojson ?

Amit Gore
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  • I'm also looking for the solution for this problem. Did you find any solution? @amit – Nishanth Duvva Sep 12 '19 at 07:34
  • @Nishanth I did not find any solution at that time, instead, I have tried using the same vector tile source to serve the business logic. I can help you out with some [thread](https://github.com/mapbox/mapbox-gl-js/issues/6957) generated at that time. – Amit Gore Sep 13 '19 at 06:29

1 Answers1

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The default maximum zoom for generating vector tiles with Tippecanoe is 14 (https://github.com/mapbox/tippecanoe#zoom-levels) and with GeoJSON sources in Mapbox GL JS is 18 (https://www.mapbox.com/mapbox-gl-js/style-spec/#sources-geojson-maxzoom). That could be the reason, but I can't tell.

I'd try doing tippecanoe to an extra zoom level (15 instead of the default 14) and see what difference that makes. Try to avoid generating to an unnecessary high zoom level as it'll just take longer to process.

I'd also omit the --full-detail=20 --low-detail=18 --detect-longitude-wraparound --no-tiny-polygon-reduction --no-tile-size-limit --no-line-simplification --no-tile-compression, the defaults are reasonable for parcels.

I'd use --detect-shared-borders to ensure those shared borders are simplified together https://github.com/mapbox/tippecanoe#attempts-to-improve-shared-polygon-boundaries.

If you just want to visually see parcel boundaries and don't need to select them you can reduce the file size with https://github.com/mapbox/tippecanoe/issues/575

You can use mbview to inspect the results from Tippecanoe locally before uploading to Mapbox.

AndrewHarvey
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  • in my case, I need to have these extra params otherwise it is creating weird geometries for the scenario here. Also, increasing the max-zoom and --detect-shared-borders isn't helpful. I wonder why is it trying to split single side to multiple ones. Is there anything I can try related to projection? – Amit Gore Jun 26 '18 at 13:59