Tabletop version

JanikCodes · October 28, 2025, 8:02am

Hi! First off, Im in love with cesium and what it has to offer, a real arcgis killer in my opinion and I’m close to using it for a commercial project.

However right now cesium does not really have much to show for the XR/VR users in terms of ‘tabletop’, a cutout visible map which is pan- and moveable. I know we can limit the visible area with the Cesium Cartographic Polygon Component (which works great) however getting those functionalities in is not straight forward (or I’m too stupid).

Let’s tackle zooming perhaps, what I’ve tried is making a limit area visible with the Cesium Cartographic Polygon, have a Polygon Raster and inverse that so only that specific area is visible, great.

Now to the zooming, usually those tabletop views work while keeping the viewable physical area the same size, so the polygon shape should not increase/decrease but the actual content inside should zoom in/out.

I tried achieving this effect by scaling the actual 3DTileSet (world) and refreshing that tileset. This ‘kinda’ works but the actual size of the visible area sadly changes slighlty, it’s not ideal.

I also tried messing with the entire Cesium Georeference global scale by changing it and at the same time adjusting the Cesium Cartographic Polygon scale, sadly I could not find a good conversion to make that work.

Any clues/hint? I couldnt find any working examples online, only failed attempts.

I highly suggest creating a new example which includes this type of scene as it’s a huge market!

Thanks a lot! Appreciate any help and looking forward.

JanikCodes · October 28, 2025, 8:10am

After searching some more I came to this PR which looks like what I need!

github.com/CesiumGS/cesium-unity

Add ability to exclude tiles by implementing a C# class.

main ← tile-excluder

opened 06:03AM - 16 Mar 23 UTC

kring

+522 -59

Depends on CesiumGS/cesium-native#608 Added `CesiumTileExcluder`, which is a …C# version of cesium-native's `ITileExcluder`. The idea is that we can add a C# class like this to our project: ```csharp using CesiumForUnity; using UnityEngine; [RequireComponent(typeof(BoxCollider))] public class CesiumBoxExcluder : CesiumTileExcluder { private BoxCollider _boxCollider; private Bounds _bounds; public bool invert = false; protected override void OnEnable() { this._boxCollider = this.gameObject.GetComponent<BoxCollider>(); this._bounds = new Bounds(this._boxCollider.center, this._boxCollider.size); base.OnEnable(); } protected void Update() { this._bounds.center = this._boxCollider.center; this._bounds.size = this._boxCollider.size; } public bool CompletelyContains(Bounds bounds) { return Vector3.Min(this._bounds.max, bounds.max) == bounds.max && Vector3.Max(this._bounds.min, bounds.min) == bounds.min; } public override bool ShouldExclude(Cesium3DTile tile) { if (!this.enabled) { return false; } if (this.invert) { return this.CompletelyContains(tile.bounds); } return !this._bounds.Intersects(tile.bounds); } } ``` And then add an instance of this class as a component on the `Cesium3DTileset` or any of its parents, up to and including the `CesiumGeoreference`. With that in place, cesium-native will call the `ShouldExclude` method for each tile that it is considering loading or rendering. This will happen a _lot_, so this method needs to be fast. Return true to skip loading and rendering that tile. Return false to load it and render it as normal. In the implementation above, a user-defined BoxCollider is also attached to the same GameObject as the CesiumBoxExcluder. Any tiles that intersect this BoxCollider are loaded and rendered, others are not. So tiles that are entirely outside of the box are ignored. The given tile's `bounds` property is an axis-aligned bounding box in the same coordinate system as the `CesiumBoxExcluder`, so it's easy to do tests like this. In this screenshot, the BoxCollider is the green box in the middle of Melbourne. All of the visible tiles are at least partially inside the box: ![image](https://user-images.githubusercontent.com/924374/225528568-647a9bb8-58c1-4635-b0dc-c24713b7ff95.png) If we disable the CesiumBoxExcluder, all the tiles load as normal: ![image](https://user-images.githubusercontent.com/924374/225528858-5986386f-7413-434f-8050-37d5ff1bc61c.png) Also in this PR: Extended Reinterop to allow constructors of blittable value types to be called from C++. On the C++ side, these are exposed as `Constrct` methods rather than C++ constructors so that brace initialization can continue to be used to initialize fields without calling into C#.

Kevin_Ring · October 28, 2025, 9:13am

Hi @JanikCodes, welcome to the community!

Yes, the comments in that PR are a pretty good example for how you can do this sort of thing in Cesium for Unity. Let us know how you go!

We happen to have a level in the Cesium for Unreal Samples project that demonstrates how to do a tabletop-like visualization, but we haven’t added one to the Cesium for Unity Samples project yet. If you get something working that you’re happy with and can share with the community, we would definitely welcome a pull request to add it to the Samples!

JanikCodes · October 28, 2025, 9:42am

Yeah I stumbled across problems others also came across. I’ll try my best to get a sample up n running but I have to figure it out myself first.

My goals for the example will be:

tabletop visualisation (Only a specific area is visible)
zoom in/out while maintaining roughly the same y axis
panning
able to move the tabletop visualisation freely in space including rotation

JanikCodes · October 29, 2025, 2:06pm

just a quick update. I’ve managed to pretty much implement everything I’ve mentioned. All that is left to do is tidy it up

I was wondering one thing for visual improvements: Is it possible to somewhat make the terrain have “thickness” which ‘fills’ empty spaces? This would mean the entire ‘tabletop’ view has some thickness to it downwards, being flat at the bottom. Not sure if I explained that correctly what I’m trying to achieve, or atleast wonder.

RSDev · October 29, 2025, 3:05pm

Hey Janik, Id be interested to see your approach to this if you dont mind sharing.

When it comes to the “thickness” as you call it I have not been able to find a suitable solution. Havent had much time to investigate though. Playing around with shaders is probably a way to do this.

JanikCodes · October 30, 2025, 8:16am

ill share project files in the next weeks (or make a git PR most likely) but it’s very straight forward.

For map pan I simply change the georeference lat/lon.
For zooming I’m relying on “CesiumTileExcluder”, most things can be taken from here github.com/CesiumGS/cesium-unity/pull/248
- Zooming works by changing the georeference scale. I’m also setting the georeference height to the highest altitude found in the tiles.
To achieve a nice looking tabletop view with clean edges I’m modifying the default “CesiumDefaultTilesetMaterial" by passing in a bounds vector and a center position vector. This way my entire ‘tabletop’ visualisation can be moved freely in world space while remaining the same geographic picture.
- One issue I have at the moment is that evertime the tabletop visualisation is moved, the map reloads due to the material property changing which reloads the tiles. This can be fixed by applying the custom material directory via code to the children meshrenderer, just didn’t got around to it yet.

Result looks like this at the moment.

RSDev · October 30, 2025, 3:16pm

Thanks for sharing. Not sure how you use the CesiumTileExcluder for scaling. Cant you just use the Scale property of a Cesium Georeference component?

As for panning and clipping I chose the same appraoch as you.

What happens when you pan the terrain and a new highest point in the tileset appears? My solution is rather choppy because I apply the sampled height in update and I only sample the center point of the table. So if there is a building suddenly sampled due to panning the height changes abruptly. Would probably be smoother if one would sample multiple points and sets the avarage height

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Tabletop version

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