Exclusion Zones

It seems that exclusion zones only work at the LOD level, so if the area being excluded is smaller than the LOD being displayed, the exclusion will have no effect. We tried doing exclusions on the OSM buildings data at the block level, but nothing happened, because apparently the OSM building data does not have a bounding region per building.

This is a problem for us where we might have a city and want to hide and replace an individual building or piece of terrain. The exclusion works as long as we are close enough and as long as our bounding regions are finely drawn. But as soon as we back up, the contents would be replaced with the LOD of the larger tile.

So, does this mean that if we need to exclude a single building, then we need to recreate the entire tileset, or at least to the level where we’d no longer notice the building being missing?

In UE, we might use HLODs to mass together and LOD multiple actors, but if we remove an actor, the whole HLOD can be regenerated with a few clicks (and a lot of waiting and praying). If we remove a low level tile from a tileset is there any similar facility for regenerating the tileset so we won’t see the contents of the tile reappear in the next LOD?

It would be really important for us to be able to exclude polygons from tiles so that an object from a tileset can be quickly and easily replaced with UE actors or other tiles. Otherwise it’s hard to understand how Cesium can be useful for architecture.

-Donald Newlands

Hello @nc3d ,

You are spot-on with your understanding of exclusion zones, they were just a quick coarse solution for clearing out large areas to make way for another tileset altogether (e.g., culling out a whole city of OSM buildings to place in a photogrammetry tileset). The good news is we are actively working on a much cleaner 2.5d clipping feature that can be drawn out with a spline and that will work for all LODs. You can follow the progress on this feature here: Support for overlaying one 3D Tiles tileset with another (clipping) · Issue #47 · CesiumGS/cesium-unreal · GitHub.

Please let me know if you have any other questions and feel free to chime in on the GitHub issue!

-Nithin

Nithin,
Thanks - that’s great news! I’ll keep an eye out for it!.
-Donald