Indexed 3D Scene Layers (I3S) – an open standard for 3D GIS visualization on Web, Desktop and Mobile Platforms

Indexed 3D Scene Layers (I3S) is an open format for streaming and storing massive amounts of heterogeneously distributed geospatial content. Adopted as the first OGC (Open Geospatial Consortium) Community Standard for 3D streaming and storage since 2017, I3S has been rapidly evolving to capture new use cases and techniques, advancing geospatial visualization and analysis. I3S enables the efficient transmission of various 3D geospatial data types, including discrete 3D objects with attributes, integrated surface meshes and point cloud data covering vast geographic areas as well as highly detailed BIM (Building Information Model) content, to web browsers, mobile apps, and desktop.

In this session, we’ll explore various aspects of I3S, including the latest update to the standard, OGC I3S Version 1.2, that brought dramatic improvements in performance and scalability. We’ll describe and demonstrate various I3S features, such as paged node access pattern – a compact Bounding Volume Hierarchy (BVH) representation that significantly reduces client-server traffic, a more compact geometry layout – using a well-known quantization encoding (Draco), advanced material definitions property that supports PBR (physically based rendering of materials), as well as support for KTX2 (Basis) compressed textures – reducing the compressed texture size by over 60%. We’ll also demonstrate collaborative & research work done to dramatically improve the speed of KTX2/Basis creation leveraging both the CPU and GPU – contributions that benefit both the geospatial and 3d graphics communities.

We will also further demonstrate various examples of the different layer types and profiles that are supported in I3S and how the data structure and organization help to efficiently store segmentation/classification information as well as triangle/point level attribution. Technological advancements in 3D graphics, data structuring, mesh and texture compression, efficient client-side filtering and so forth have significantly contributed to a paradigm shift in how geospatial content is created and disseminated, regardless of size and scale. Formats such as I3S now allow 3d content to be authored/created once and be efficiently consumed in various platforms including desktop, web and mobile for both offline and online access. This phenomenon – create once and consume everywhere model, has encouraged the dissemination and sharing of geospatial content for both planetary (whole earth) and planar 3D visualization experiences. The session will show case numerous examples (for desktop, web, and mobile experience) illustrating the many advancements made in geospatial technologies that are ripe to be embraced in various geoscience disciplines.

Lastly, we’ll close by showcasing various patterns for distributing 3D content via I3S and demonstrate its consumption thru open-source solutions such as loaders.gl and CesiumJS, supporting the latest version of I3S. We’ll also show latest additions to Tile Converter, an open-source solution that allows a two-way conversion between 3D Tiles and I3S, further fostering interoperability in the geospatial community.