The polygon is flat, but at the date line, there is, what appears to be, a wall coming down from the polygon.
This looks like a bug to me. Is there a workaround? Or, have I missed something?
I’m not sure exactly where the vertical extension in coming from. It looks like a skirt? These are usually a part of terrain tile rendered to ensure there are no gaps visible.
In general, there are some improvements that are needed for very large polygon rendering. As a workaround, we suggest breaking up the shape into smaller ones ahead of rendering, such as with turf.js.
Should a bug report be entered against this one?
Also, I tried making the polygon smaller and the artifact was still there, although increasingly diminished the smaller the polygon became. It looks like the only thing that matters is that it crosses the date line.
Ah, thanks @eric-g-97477! I didn’t notice the IDL factored into the issue.
There’s an existing issue for this at Visible GroundPrimitive seam at IDL and Prime Meridian · Issue #4746 · CesiumGS/cesium · GitHub. I’ve gone ahead and added your report there.
An aside: I had tried out a workaround that was pretty similar to that described in Visible GroundPrimitive seam at IDL and Prime Meridian · Issue #4746 · CesiumGS/cesium · GitHub , but unfortunately, that is not directly applicable to polygon (but only to rectangle)
@Gabby_Getz Thanks for adding the report. Hopefully the bug can be fixed soon.