Gaussian Splats

Gaussian Splats let you bring 3D Gaussian Splatting reconstructions into your scene as a lightweight, photorealistic alternative to a full mesh or photogrammetry tileset. They are a great fit when you want a faithful look at a scanned site without the weight of a heavier 3D Tiles model.

In SiEGA Web, a Gaussian Splat is processed and tiled in Cesium Ion first. Once it lives there, it is pulled into your account automatically, so there is nothing to upload from inside the viewer.

Find Your Splat in the Asset Library

Your splats are pulled from your Cesium account, which is connected through your AERO AI dashboard, so they appear in the Asset Library on their own with no setup in the viewer. Open the Asset Library from the side panel and look under 3D Tiles to find your splat in the list.

Load It Into the Scene

Find your splat on its asset card and click the cloud download icon to stream it into the scene. The icon turns into a blue check once the splat has finished loading.

To view your splat, click the eye icon on the right side of the card and the camera flies straight to it.

Known Display Issues

If your splat looks blurry or jittery after loading, even though it looked sharp in Cesium Ion, the fix is quick and happens in the source file before upload. Expand the section below for the full walkthrough

Fixing a Blurry or Jittery Splat

Sometimes a Gaussian splat that looks sharp in Cesium Ion shows up blurry and jittery once it loads in the viewer. When that happens, the cause is almost always the orientation of the source file, not the viewer.

The tools involved

• PLY file is the raw file a Gaussian splat is saved as, straight out of your capture or training tool. It carries both the splat itself and its sense of which way is up.

• SuperSplat is a free, browser based editor for viewing and cleaning up Gaussian splat PLY files. You use it to correct the file's rotation before upload. [SuperSplat]

• Cesium Ion is the service that processes and tiles the PLY so it can stream into the viewer. Ion trusts the orientation baked into the file, so if that orientation is wrong, the tiled result inherits the problem.

What is going wrong

A Gaussian splat carries its own idea of which way is up. When that does not match the coordinate system Cesium expects, the renderer fights the data and the splat comes out fuzzy and unstable. Adjusting the transform in Ion's Location Editor does not fix this, because the orientation inside the file is still wrong. The reliable fix is to correct the orientation in the source PLY in SuperSplat before it ever reaches Ion.

How to fix it in SuperSplat

1. Open SuperSplat and load your PLY file. [Link placeholder: SuperSplat]

2. Select the splat and find its rotation values.

3. Change the rotation from 0 X, 0 Y, 180 Z to -90 X, 0 Y, 0 Z. This turns the splat so its up direction matches what Cesium expects.

4. Export the corrected file from SuperSplat.

5. Upload the exported file to Cesium Ion and let it finish tiling.

Once the corrected splat is in Ion, load it into the viewer as usual and it will come in sharp and stable, in the right place on the globe.

Want the full background?

The Cesium community worked through this exact issue, including confirmation from a Cesium team member that the fix belongs in the source file. For the deeper discussion, see the forum thread. [ CesiumJS forum thread]