How to combine exterior boundary clipping with interior hole clipping using CesiumPolygonRasterOverlay?

[APPIA_Pau]

Hi everyone,

I’m working on a project where I need to clip a harbor area from Cesium tileset data. My goal is to:

1. Clip the exterior - Hide everything outside the harbor region (so only the harbor + a small section of the city loads)

2. Clip the interior - Remove the water areas within the harbor by cutting out multiple polygon sections

My current setup:

• Using Unreal Engine 5.6.1

• Created multiple CesiumCartographicPolygon actors:

  • One exterior polygon defining the harbor boundary

  • Several interior polygons defining water areas to remove (imported from GeoJSON)

• Attached a CesiumPolygonRasterOverlay component to my Cesium3DTileset actor

• Selected all polygons in the overlay’s polygon references

The problem: The CesiumPolygonRasterOverlay has a single “Clip Inside/Outside” setting that applies to ALL selected polygons uniformly. This means:

• If I set it to clip outside → the exterior polygon works (shows only harbor area), but the interior polygons do not clip the water zones (wrong behavior)

• If I set it to clip inside → the interior polygons work (cuts out water), but the exterior polygon also clips inside (hides everything, showing only what’s outside the harbor boundary)

• If I only use the interior water zone polygons, they all clip and overlap correctly. If I only use the exterior it also clips the outside correctly.

What I need:

• Exterior polygon: Clip outside (exclude everything beyond harbor)

• Interior polygons: Clip inside (exclude water areas within harbor)

Is there a way to achieve this with the current Cesium for Unreal implementation? Can different polygons have different clipping modes, or is there an alternative approach I should be using?

Thanks in advance for any guidance!

[pjiang9]

Hi, @APPIA_Pau

Here is a solution.

1.the setting of MI_CesiumThreeOverlaysAndClipping2

(1) Copy Plugins >Cesium for Unreal>Materials>Instances>MI_CesiumThreeOverlayAndClippingAndWater to the content of the project folder.

(2) Rename it, for example, MI_CesiumThreeOverlaysAndClipping2.

(3) Make some changes as the following image. Note that the ClippingInner is on the top layer of the ClippingOuter.

2. the material setting of Cesium3DTileset for the terrain

3. the setting of CesiumPolygonRasterOverlayOuter

4. the setting of CesiumPolygonRasterOverlayInner