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We get multiple problems when rendering complex data with the MVT Tileset writer:

 

  • Small polygons vanish on different zoom levels
  • Lines are on some zoomlevels so simplified, they look like a subway plan (see screenshot)
  • Some content does not get rendered at all on some tiles, but is visible on neighbouring tiles at the same zoomlevel (see screenshot)

 

The data we render consists of 5 input layers. Polygons and points are mixed in the tileset, but homogenous for each layer. The input polyogons are very complex (lots of vertices per polygon). We produce a single tileset with the input data.

 

MVT Tileset writer parameters are default.

 

We als tried with simplification parameter "2" with the same results. It is not really clear what number to use with the simplification parameter, the documentation is not clear. Maybe someone can provide samples how to calculate the number to fill in?

 

FME version is 2021.0.3 b21326. Viewer is QGIS 3.18.3. Viewing with maputnik shows the same results.

 

Rendering the same data with tippecanoe works.

 

Any ideas?

 

vt1Points on in the tile right not rendered in the tile left. Lines look massively simplified, like a subway plan, but simplification parameter is 0. Input for line data is river data. Smaller poylgons are vanished.

 

vt2Center tile has no points rendered?

 

vt3Zoomed in, everything looks ok.

I played with the river lines alone and increased the max tile size to 10 MB, so the lines looks good now. The biggest tile I found is around 3,5MB on zoomlevel 5. That is way too big. I tested several variants of the simplification parameter, 0.5, 2, 10, 20, 200, but the tile size does not change. So i think the main problems described in the post exists because of the default limitation to 500kB per tile. Increasing this limit helps with the rendering problems, but the tiles are too big now. I´m not able to change the size of the tiles through simplification, because the simplification parameter and the description makes currently no sense to me.

 

So maybe the question tends to be more about the simplification parameter. If the simplification would work, the file size will shrink and the rendering problems won´t appear anymore 🙂 Any hints?

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