Cesium

Cesium is the open geospatial platform behind the 3D Tiles specification and the CesiumJS rendering library, and it is the route by which gaussian splats reach a georeferenced globe. The organisation began in 2011 inside aerospace software company Analytical Graphics, Inc., now Ansys, where a team led by Patrick Cozzi built a time dynamic virtual globe. It was open sourced in 2012, spun out as an independent company in 2019, and joined Bentley Systems in September 2024.

Splat support runs through the same machinery as the rest of Cesium's data. Cesium brought KHR_gaussian_splatting support to CesiumJS and Unreal Engine in March 2026, following the Khronos Group's glTF release candidate for gaussian splatting in February. Hierarchical level of detail for splats landed in 3D Tiles, CesiumJS and Cesium for Unreal in April, which is what lets a splat tileset be streamed and culled at world scale rather than loaded whole. In June, the Cesium ion reconstruction pipeline stopped requiring mesh generation for gaussian splat workflows, removing a step that had been mandatory even when the mesh was never used.

CesiumJS 1.144, released on August 1 2026, is a maintenance release for splat handling. It fixes SPZ compressed splat loading so the compressed payload is read from the buffer view declared by KHR_gaussian_splatting_compression_spz_2, which prevents incorrect cache reuse when two assets carry SPZ payloads in different buffer views. The same release fixes a crash when decoding large SPZ files at high spherical harmonic degree, corrects the splat modelMatrix not being applied to positions, rotations and scales when a tileset transform changes, corrects spherical harmonic view direction being evaluated in the wrong coordinate frame for datasets without an embedded axis-compensation matrix, fixes a WebGL crash above roughly 16 million splats, and closes a memory leak in splat tileset rendering. It also adds support for Reality Data of type GaussianSplat3DTiles in ITwinData.createTilesetForRealityDataId, which is the Bentley iTwin path into a Cesium tileset.

CesiumJS is Apache 2.0 licensed and free to use. Cesium ion, the hosted tiling and streaming service, is priced separately. The Community plan is free for individuals and covers personal and non-commercial use with support through the community forum. Commercial is $149 per month for an individual and $524 per month for a team. Premium is $499 per month for an individual and $874 per month for a team. Custom pricing is quoted through sales. Every plan carries the same capability set, including global 3D imagery, terrain and buildings, 3D tiling, reality modeling and analysis, streaming, clipping, Cesium ion Stories and the REST API.