Polygon errors when using perPositionHeight

My goal is the visualization of an elevated extruded polygon with data provided to a GeoJsonDataSource.

• The polygon is given by a GeoJson dataset, consisting of points where each is given by longitude, latitude and elevation (e.g. [ 30.0, 70.0, 152452.62 ])
• The polygon should be extruded by 30502.

A schematic profile view of such a volume could look like this:

• Green: Bottom of the polygon (given by the dataset) -> should follow the ellipsoid in 3D
• Red: Extrusion
• Orange: Top of the polygon (given by dataset & extrusion) -> should follow the ellipsoid in 3D

Now to the pratical part: I am using the following GeoJson data: polygon.zip

When using the data provided above, the visualization with GeoJsonDataSource shows some strange rendering effects. It looks like the geometry folds and cuts the globe (bottom and top of the polygon not properly following the ellipsoid):

I have also tried to visualize the polygon by using PolygonGeometry but unfortunately there are also some rendering issues:

• There is an edge in the visualization (the geometry seems to fold or cut the earth)
• When having certain view-angles the folding/cut is even more visible

So basically the issue is, that the top and bottom surface of the volume do not follow the ellipsoid properly.

• Is there any way to avoid those rendering artifacts?
• Is this issue known? Especially when using very large polygons? Actually I’m not quite sure if this is a bug, I’m missing some configurations or I´m using a wrong approach. I also could not find any sample yet which is dealing with such kind of visualizations.

I would really appreciate any help. 😃

[hpinkos]

The above looks like a data problem. I think his position heights are lower than the extrudedHeight. I’ll add a comment to #2924

[cesium-concierge]

Congratulations on closing the issue! I found these Cesium forum links in the comments above:

https://groups.google.com/forum/#!searchin/cesium-dev/paula|sort

If this issue affects any of these threads, please post a comment like the following:

The issue at https://github.com/AnalyticalGraphicsInc/cesium/issues/5203 has just been closed and may resolve your issue. Look for the change in the next stable release of Cesium or get it now in the master branch on GitHub https://github.com/AnalyticalGraphicsInc/cesium.

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