Registration is now open for the 2025 Cesium Developer Conference! Save your spot.

Cesium for Omniverse v0.24.0

Cesium for Unity Samples v1.16.0

CesiumJS 1.129

CesiumJS

In April, we attended the 40th Space Symposium, hosted the Philly Postgres meetup and PhillyCHI UX panel, and released the full agenda for the Cesium Developer Conference. (Will we see you there?) Today we announced 3D Tiles for Godot, an open source plugin for Godot Engine built by Battle Road through the support of a Cesium Ecosystem Grant.

New York City, New York, USA, visualized with Google Photorealistic 3D Tiles via 3D Tiles for Godot. Courtesy Battle Road.

We made improvements across Cesium this month. To get notifications about our monthly releases, you can subscribe to the Cesium release roundup thread on our community forum.

CesiumJS 1.129 is now available. Highlights of the release include:

VoxelProvider.minimumBounds and .maximumBounds are now specified as physical values, rather than shape space values. #12592 

Added Material with Custom GLSL Sandbox Demo. #12549 

QuadtreePrimitive.updateHeights now converts position to Cartographic before invoking the callback, ensuring compatibility with change introduced by commit 53889cb and preventing unnecessary computation. #12555 

Fixed Polyline*MaterialProperty width artifacts (reverted #12434). #12506 

New Sandcastle showing off a Material with custom GLSL shaders by user Hiwen. 

Cesium for Unreal v2.16.0 is now available. Highlights of this release include:

Added the ability to query the Cesium ion geocoder from Blueprints to resolve place names and addresses to longitude and latitude. 

Added UCesiumMetadataPickingBlueprintLibrary::FindPropertyTableProperty to search for a FCesiumPropertyTableProperty by name on a given UPrimitiveComponent. 

The request cache will now use FPaths::ProjectUserDir instead of FPaths::EngineUserDir on non-Android and non-iOS platforms, fixing a permissions issue in Development builds. 

Fixed a linking issue introduced in v2.15.0 in GoogleTilesTestSetup. 

Point cloud tiles will now be upsampled for raster overlays, fixing an issue where applying a raster overlay to a point cloud tileset would cause holes to appear. 

Fixed a crash caused by invalid I3dm headers. 

Check the Cesium for Unreal release and the Cesium for Unreal Samples release for the full list of updates.

Download the Cesium for Unreal plugin from Epic Marketplace

Bing Maps Aerial imagery draped on an attenuated point cloud of Mount St. Helens in Cesium for Unreal. Point cloud generated from LAS data provided by https://liblas.org.

Cesium for Unity v1.16.0 is now available. Highlights of this release include:

Added CesiumUrlTemplateRasterOverlay component, allowing a raster overlay to be added using tiles requested based on a specified URL template. 

Fixed a bug where credits would not display in the Game tab after entering Play Mode. 

Improved stability during AppDomain reloads by catching exceptions thrown while freeing tiles. 

Check the Cesium for Unity changelog for the full list of updates, and follow our Cesium for Unity tutorials to get started. 

Cesium for Omniverse v0.25.0 is now available. Highlights of this release include:

Cesium for Omniverse now targets Kit 106.5. 

Peruse the changelog for the full list of updates, and get started with our Cesium for Omniverse tutorials.

Download the Cesium for Omniverse extension

Download the Cesium for Omniverse samples

Improved tileset load times by 50% and rendering performance by 15% by reducing the number of draw calls and decreasing the amount of geometry rendered for any given view. 

Improved support for parsing sidecar files with CRS data. 

Cesium ion for Autodesk Revit Add-In 1.2.0

Added support for an elements unique ID, level, and room metadata. 

Removed unused root node project level metadata. 

Fixed crash when exporting with textures enabled and metadata disabled. 

Check the changelogs for the full list of updates for Cesium ion SaaS and Cesium ion Self-Hosted.

Buendea uses Cesium Moon Terrain to support NASA’s Advanced Operations Concepts Lab (NAOCL), ensuring astronauts’ virtual training accurately reflects the lunar environments they’ll encounter when they leave home. XR Operations Support System (XOSS) is a collaboration between Buendea and NAOCL, based out of Johnson Space Center (JSC) in Houston, Texas, USA. XOSS users have the entire Moon in their simulation and can further immerse themselves in nine potential landing and habitation sites near the lunar South Pole, where Cesium Moon Terrain has its highest resolution data and Buendea has added additional high-res surface data. 

XOSS in VR mode. Courtesy Buendea and NAOCL.

This summer’s inaugural Cesium Developer Conference, June 23-25 in Philadelphia, is an opportunity for developers to network and learn about the latest and greatest open geospatial tools, standards, and data. For attendees looking for a hands-on experience to learn Cesium, we are excited to offer the "Cesium Deep Dive," a pre-conference training full-day workshop on Monday, June 23.

Register and select the Cesium Deep Dive training

Northern California, USA, using Google Photorealistic 3D Tiles in CesiumJS.

If you are a burgeoning geospatial developer, this workshop is for you.

Bring your own laptop so you’re prepared to build, ask questions, and learn new skills to take your 3D geospatial projects to the next level.

Training includes intros to CesiumJS and Cesium ion, then explores deeper discussions on deploying Cesium Native and using 3D creation engine plugins. 

Engineers will present ready-to-try exercises and will be present to help you explore features of Cesium and 3D Tiles. There will also be opportunities for you to meet 1:1 with engineers if you need help with a specific question.

We’re excited to have two special guests presenting and mentoring attendees throughout the day:

Tim Woodard, Principal Solutions Architect at NVIDIA, will present an update on NVIDIA Omniverse and how using it can benefit open geospatial developers.

Stephen Phillips, Solution Architect at Epic Games, will give an overview of how Unreal Engine can be used in AEC and geospatial applications.

Using Cesium runtime plugins for geospatial context

Unreal Engine for geospatial and AEC applications

NVIDIA Omniverse architecture and applications

Prior to the workshop, the Cesium team will send out information to registered training attendees with instructions for downloads and device configuration so that you are ready when you arrive.

The Grand Canyon, USA, visualized with Cesium for Omniverse.

Will I become a Cesium Certified Developer?

We’ve been getting this question a lot: Will a workshop attendee automatically become a Cesium Certified Developer?

No. Certification is based on one's ability to deploy the skills covered throughout this workshop in their own work. You will learn many of the skills needed for certification over the course of the day, and then it will be up to you to put these skills into practice and submit your project. Our Certification team will be on site throughout the full conference to discuss certification. 

Learn more about becoming a Cesium Certified Developer here.

Sign up for the training through the regular conference registration process. There is an additional fee ($100) to attend the workshop because space is limited. Lunch and refreshments are provided.

Slots are filling up. We look forward to learning with you.

Register for the conference and add the workshop

Deep Dive Workshop at the Cesium Developer Conference

In March, we attended NVIDIA GTC 2025, presented at The Khronos Group’s “3D on the Web” during GDC 2025, and shared that the Cesium Design Tiler now preserves metadata from Industry Foundation Classes (IFC) when tiling into 3D Tiles. 

We’re also hard at work on finalizing the agenda for the 2025 Cesium Developer Conference. Register to join us in Philadelphia in June.  

Color ramp shading based on an IFC length property in Cesium for Unreal. Data source: BSI (2020) "Medical-Dental Test Files," buildingSMART International—accessible via GitHub.

CesiumJS 1.128 is now available. Highlights of the release include:

Added support for loading iTwin data using share keys as an alternative to user-based OAuth. When using a share key, set ITwinPlatform.defaultShareKey. #12530 

Added Frozen.EMPTY_OBJECT and Frozen.EMPTY_ARRAY for use as default parameter values that avoid unnecessary memory allocations. #12507 

Fixed entity tracking for delayed datasource bounding spheres. #12465 

Camera.getPickRay now correctly returns a ray with origin in world coordinates in orthographic mode. #12500 

Fixed camera zooming in 3D orthographic mode when pixelRatio is not 1. #12487 

Fixed shape bounds and transforms for cylinder-shaped voxels. #12522 

Fixed an issue where clamped entities' height updates could stall when using high-resolution terrain due to a growing queue of tiles in updateHeights in QuadtreePrimitive. #12476 

Cesium for Unreal v2.15.0 is now available. Highlights of this release include:

Actors spawned through the Cesium editor panel, such as tilesets and cartographic polygons, will now be parented to the first selected georeference—if any—instead of always being parented to the first georeference in the scene. 

WorldHeight Runtime Virtual Texture output is now set to the Z component of the world position. 

Fixed a bug where a glTF material with alphaMode=BLEND would be rendered as opaque if its baseColorFactor was not set. 

Fixed a crash that could occur when rapidly refreshing a tileset. 

Fixed a crash when tilesets with point clouds were used in combination with Hardware Ray Tracing. 

Worked around an apparent Metal problem that prevented polygon clipping from working correctly on macOS. 

Fixed normals being incorrectly written to Runtime Virtual Texture output in tangent space instead of in world space. 

When a glTF contains external resources like textures and buffers, requests for these external resources now include query parameters that were used to request the original glTF. This is important when using access tokens and similar. 

Fixed bugs that could prevent valid metadata in Instanced 3D Model (i3dm) files from being parsed correctly. 

Fixed a small memory leak while reading glTF files. 

Cesium for Unity v1.15.5 is now available. Highlights of this release include:

Fixed a bug that could cause a crash when reloading a scene or tileset repeatedly. 

The Cesium Design Tiler now preserves metadata from Industry Foundation Classes (IFC) when tiling into 3D Tiles. Metadata support includes IFC attributes, property sets, and properties. Read more. 

As part of our ongoing effort to improve performance, we are adding a "Region" field to Cesium ion. New users will be asked to set their region when setting up their account. For existing accounts, we will automatically set the region based on the locations from which data requests have been made in the past year. 

glTF node names are now preserved as metadata. 

IFC metadata attributes type detection added, no longer limited to just strings. 

fix for a regression with terrain water masks 

Blyncsy uses CesiumJS to show potential users how the company’s roadway data can be used in a visualization engine. 

The Weather Company improves military training and planning by pairing its detailed weather data with geospatial context in apps using Cesium for Unreal and CesiumJS.   

Defense and other government agencies rely on current weather information, forecasts, and historical data for situational awareness and effective decision-making. The Weather Company (TWC) improves military training and planning by pairing its detailed weather data with geospatial context in apps using Cesium for Unreal and CesiumJS.  

WeatherverseTM provides accessible, accurate, and actionable government weather forecast data and visualizations to improve outcomes, reduce costs, and help protect lives. Courtesy The Weather Company.

The Weather Company: Weatherverse

TWC was founded in the 1980s, addressing needs across various industries, and began serving government agencies in 2022. Sudden changes in weather conditions affect personnel and equipment, even with otherwise meticulous planning.  

Weatherverse Sim prepares warfighters with accurate 3D visualizations of environments and conditions—such as strong wind, more rain, or less cloud coverage—simulating weather they might face in the field. With recording and playback, trainees can experience and memorize scenarios for anywhere in the world, and trainers can adjust future sessions. Google Photorealistic 3D Tiles are streamed with data from TWC’s SUN Spatial Data Services and other sources for a comprehensive picture. Weatherverse Sim has used Cesium for Unreal since 2023 to bring realistic weather elements and geospecific terrain to these simulations, increasing operational effectiveness. 

Weatherverse Sim uses Cesium for Unreal to combine weather elements and terrain. Courtesy The Weather Company.

Weatherverse Planner monitors the forecast for locations important to planning teams and their missions, so they know what impacts weather will have on aviation, communications, infantry, and more. Users set thresholds and alerts for conditions like lightning, wind, or precipitation, for example, to make better informed decisions. Weatherverse Planner can be used as a stand-alone solution or integrated as a widget within any CesiumJS-based app for reliable performance on the web, streaming Bing Maps Aerial imagery for the view from space. Fusing weather data and geospatial context instead of managing multiple separate systems concurrently saves time and lives. Weatherverse Planner has used CesiumJS since 2024. 

Weather risk, based on user-defined parameters, in Weatherverse Planner. Courtesy The Weather Company.

Precipitation in Weatherverse Planner. Courtesy The Weather Company.

Weather conditions in Singleton, Australia, in Weatherverse Planner. Courtesy The Weather Company.

SimCentric’s CesiumJS-based SAF-Foresight app for planning and safety for live fire exercises will deploy Weatherverse Planner as a plugin for Exercise Talisman Sabre 2025. Exercise Talisman Sabre is the largest combined military training activity between Australia and the United States, with other partner nations joining, and this year it will incorporate real-time weather information to improve readiness. 

The Weather Company has built on top of CesiumJS as a plugin to further support and integrate Weatherverse Planner. The TWC-Cesium Plugin includes the protocols for acquiring, storing, querying, and filtering weather data from its SUN weather and spatial data services and integrates with existing Cesium-based apps. It is in an experimental phase. 

“Cesium provides a deep and rich set of capabilities, especially with regards to 3D orientation and geospatial data visualization. The framework is also well documented, approachable, and performant,” said J.R. Cottingham, senior director for The Weather Company’s Weatherverse. 

Weatherverse Planner deployed as a widget in CesiumJS-powered SAF-Foresight. Courtesy The Weather Company and SimCentric.

TWC is working to improve Weatherverse Planner with additional weather visualizations, such as wind streams. 

Built on open standards to support interoperability and with commitment to rapid innovation, Cesium powers mission-critical applications to better understand the operational environment. Read more federal and defense-related stories. 

The Weather Company Brings Forecasts to Military Planning with Cesium 

Keeping roads well maintained and safe for travel requires up-to-date information about roadway conditions, including potholes, missing signage, guardrail damage, and other potential safety hazards.  

Blyncsy, founded in 2014 and acquired by Bentley in 2023, uses AI, machine vision, and cloud computing to help US state and local transportation agencies spot issues more efficiently than with resource-heavy manual methods. CesiumJS plays a critical role in helping Blyncsy show potential users how the company’s data can be used in a visualization engine. 

Striping retroreflectivity across the US. Courtesy Blyncsy. 

Blyncsy gets road pictures by crowdsourcing images from over 1,200,000 vehicles, including privately owned commercial and fleet vehicles and delivery trucks. The company anonymizes the data and securely stores it in the cloud, where it can be studied and analyzed by machine learning systems, machine vision, and AI. The analyzed data is then delivered to users through Open Geospatial Consortium (OGC) APIs, ensuring seamless integration with a variety of platforms, including Cesium and other transportation management systems, for georeferencing, visualization, and analysis.  

“Selling data is abstract. Since the beginning, long before we were acquired, CesiumJS has provided a flexible, easy to use, and high-performing way to show the value of our solution to potential customers,” Pat Brown, principal software engineer at Blyncsy, explained. “Cesium’s open-source approach was also a big draw for us—it gave us the freedom to innovate without being constrained by licensing fees or proprietary limitations.” 

Brown and his colleagues use CesiumJS not only to attract new business but also to save valuable engineering resources: “With CesiumJS we can focus our team’s time on building our platform instead of the front-end engineering that would be needed to eloquently visualize the data.” 

US interstate highway system roadway safety and maintenance conditions. Courtesy Blyncsy.

In 2023, Blyncsy began publishing a series of their AI-powered detection maps to provide state and local agencies with free access to select datasets. Built on CesiumJS with TerriaMap, that series includes a comprehensive public map of all interstate highways in the continental US, showing key roadway assets such as guardrails, speed limit signs, and work zones to support roadway safety and maintenance conditions.  

Laura Chace, president and CEO of Intelligent Transportation Society of America (ITS America), lauded the release of Blyncsy’s publicly available maps. ITS America was established by Congress in 1991 to serve as an advisor to the US Department of Transportation and advocates for a smarter, greener future transformed by transportation technology and innovation. 

“The application of advanced technologies like AI, combined with new sources of data, are transforming the transportation sector, giving us better information as we make investments in safety and mobility,” Chace said in a Bentley blog. “We applaud companies like Blyncsy for deploying these forward-thinking technologies and making this digital infrastructure data available to the public in an accessible format.”  

Blyncsy uses AI, machine vision, and cloud computing to help US state and local transportation agencies spot roadway issues. Courtesy Blyncsy.

Learn to easily and eloquently visualize and analyze data from multiple sources with CesiumJS.  

Join us at the 2025 Cesium Developer Conference to connect with Blyncsy and others with technically oriented, community-driven tracks. 

Blyncsy Shows Transportation Agencies the Future of Roadway Maintenance with CesiumJS

In February, we explored enhancements to our lighting system in CesiumJS, attended Geo Week and the LA Geospatial Summit, and opened registration for the 2025 Cesium Developer Conference. Join us in June for technically oriented, community-driven tracks at our inaugural event. 

CesiumJS 1.127 is now available. Highlights of the release include:

Updated Cesium3DTilesVoxelProvider to load glTF tiles using the new EXT_primitive_voxels extension to more closely align with the rest of the 3D Tiles ecosystem. Tilesets using the previous custom JSON format are no longer supported. #12432 

Updated the requestData method of the VoxelProvider interface to return a Promise to a VoxelContent. Custom providers should now use the VoxelContent.fromMetadataArray method to construct the returned data object. 

TextureAtlas has been refactored and internal APIs have been updated. 

Implemented texturesByteLength, visited, and numberOfTilesWithContentReady in VoxelPrimitive.statistics. 

Procedurally generated box voxels in CesiumJS.

Cesium for Unreal v2.14.0 is now available. Highlights of this release include:

Added support for drawing 3D Tilesets to Runtime Virtual Textures. 

Added support for "enum" properties in EXT_structural_metadata. 

"External Tilesets" are now unloaded when they are no longer used. This will significantly reduce the growth of memory usage over time when using Google Photorealistic 3D Tiles and similar tilesets. 

Left: building roofs overlaid onto the Cesium OSM Buildings tileset using a Bing Maps Raster Overlay. Right: building roofs overlaid onto the Cesium OSM Buildings tileset using the new Runtime Virtual Texture support in Cesium for Unreal v2.14.0.

Cesium for Unity v1.15.4 is now available. Highlights of this release include:

Comparison of memory usage from loaded tiles over time in Cesium for Unity v1.15.3 as compared to the new release, Cesium for Unity v1.15.4.

Assets now support multi-selection for deleting multiple assets at once. 

Cesium Stories annotations provide an option to show the name of the annotation in the 3D view. 

Added the ability to import source data from Azure and export tiled asset data to Azure. This must be enabled under the features section of values.yaml. 

Cesium Stories now include annotation features for points, polygons, and polylines. 

Assets page now supports multi-selection for deleting multiple assets at once. 

A new installer script is available to assist with single node installations using Microk8s. 

New tabs are now available on the Administration panel when running with SAML mode. These tabs allow administrators to view the users in the system, upload an asset to a user's account, delete assets from a user's account and re-run failed jobs through the UI. 

The Administration panel now also provides access to the logs of a failed job through the Cesium ion UI. 

Tiler updates will be available this month. Highlights will include: 

- Major announcements 
    - The design tiler will be included in the official 3D Tiling Pipeline release. 
    - The `tilers` executable will be split into separate executables: `reality-tiler` and `design-tiler`. 

- Design Tiler 
    - Add support for line and point primitives. 
    - Add support for IFC metadata. 
    - Meshopt compression applied to instance attributes. 
    - Input models that don't contain metadata pickable. 
    - Fix reading .obj models. 
    - Fix bug where Draco compression would sometimes generate extra vertices. 
    - Fix bounding volume alignment when geometry is far away from the origin. 
    - Fix texture coordinate scaling when input model uses `KHR_texture_transform`. 
    - Improve coordinate conversion for instanced geometry. 
    - Variety of metadata related improvements. 

- Clip Tileset 
    - Fix a bug that could cause `clip-tileset` to excessively upsample while clipping tilesets with raster overlays. This could cause the process to take an excessive amount of time, or to run out of memory and crash. 

- Reality Tiler 
    - Remove support for the `--sanitize-error-logs` CLI flag; paths in error logs are now always sanitized by default.
    - Add support for tiling models with vertex colors. 

Author’s note: Many thanks to my colleague Jeshurun Hembd for his significant contributions to these results. This is part 2 in a series about visual quality improvements in CesiumJS; read part 1 here.

With the growing adoption of Cesium for Unreal and Cesium for Unity, developers of native applications have raised the bar for visual quality in Cesium apps. Specialized game engine features—like dynamic sun and sky lighting components, light probes, and global illumination systems—now can be applied to geospatial use cases. The CesiumJS squad has been working to bring browser-based geospatial apps to a new level with dynamic approaches to lighting.

glTF model of a polished metal sphere reflecting the environment, rendered in CesiumJS using improved image-based lighting and an HDR-image environment map.

Good lighting is essential to make the most out of physically based rendering, or PBR, a rendering technique common to both models and 3D Tiles. Think of a polished metal sphere: It’d appear flat and dull without anything interesting to reflect. To complement recent rendering improvements we’ve made to the glTF material model in CesiumJS, we’ve shipped several enhancements to our lighting system over the last few releases, including:

Refinements to the image-based lighting pipeline

New York Buildings 3D Tileset, rendered in CesiumJS with ambient occlusion before these lighting updates (left, version 1.121) and after (right, version 1.125). The overall effect of the changes is more realistic lighting and more easily understood model form.

There are many strategies for lighting, but one tried-and-true method that’s been a part of CesiumJS for several years is image-based lighting, or IBL. Lighting for glTF PBR models and 3D Tiles combines a single directional light source (i.e., the sun) and IBL to simulate a variety of dynamic lighting conditions, such as the precise position of the sun based on time and geospatial location or scattering of light through the atmosphere.

glTF model, courtesy of noe-3d.at on Sketchfab, rendered in CesiumJS with directional lighting (left), image-based lighting (middle), and a combination of directional and image-based lighting (right). The combination results in the most apparent dimension and sense of place when viewing the model.

IBL is an appealing approach because it simulates a complex lighting environment—like hemispheric lighting from the sky, diffuse reflections from the ground, and any other light sources in a scene—with a single environment map. This map encodes a high dynamic range of lighting info in an omnidirectional texture, typically with an HDR image supplied by the user or a procedural texture generated at runtime.

While users have been able to import their own environment maps, this required offline use of external tooling like Khronos’s glTF IBL Sampler for preprocessing, making it less accessible to those without a knowledge of lighting pipelines. With our recent work, we can now use dynamic environment maps in CesiumJS that adapt to changes in time of day, atmospheric conditions, or model positioning. This means CesiumJS developers get the full benefits of IBL without any additional configuration.

Created on the GPU, dynamic environment maps can be updated in near-real time to reflect the current sun position and model location. When time of day, atmosphere settings, or model position change significantly, the environment map can be updated in the background over a few frames.

The Damaged Helmet glTF sample model rendered in CesiumJS with default procedural lighting in version 1.121 (left) and with dynamic environment maps in version 1.125 (right).

For apps with more specific lighting needs, there are options that can be adjusted, like the overall intensity of the light or the color reflected by the ground.

Our existing shaders for simulating the sky atmosphere based on time of day were flexible enough to be reused by adapting the viewing angle to the model origin. This means we can simulate lighting conditions at sunrise or sunset but also high up in the atmosphere for aircraft and satellites.

A glTF model of a polished metal sphere reflecting the environment at morning (left), noon (middle), and evening (right), as rendered with dynamic environment maps in CesiumJS.

From the environment map, we can determine both the diffuse lighting as well as the specular reflections on any model or 3D tileset. For low-roughness materials like polished metals, the environment map can be used to look up the reflection coming from any particular direction. Rougher objects scatter light and therefore reflect light in a more diffuse way. To represent this, we need to compute the average light contribution across a range of angles representative of the degree of scattering, an operation which involves sampling the environment map hundreds, if not thousands, of times. 

To optimize runtime performance, we precompute values on the GPU when a model is first loaded and then store them in data structures for lookup at runtime. The environment map is stored as a cubemap for quick lookup based on the direction of the reflected ray. Specular maps corresponding to various material roughness levels are stored in texture mipmaps that are used to sample the specular radiance. Finally, diffuse irradiance—that is the sum of all incoming light for any particular direction—is represented with third-order spherical harmonic coefficients, a total of nine sets of RBG values.

Data structures used for IBL precomputed on the GPU in CesiumJS: From the environment map, a cubemap is created with each increasing mipmap level representing the specular reflections of materials with increasing roughness. The most diffuse lighting is stored as an array of spherical harmonic coefficients.

Another key improvement to our existing IBL implementation came from revisiting our cubemapping. We switched our environment map pipeline from octahedral projection mapping, a method which worked great as a stopgap solution in WebGL 1, to native cubemaps supported by WebGL 2. The simplified approach removed redundant work on the GPU and made it significantly easier to fix bugs with LOD selection for specular maps.

Ambient occlusion, or AO, is key for understanding the form and depth of untextured models, such as those seen in OSM Buildings data or architectural design models. This technique darkens areas which would receive less ambient or indirect light, like corners or creases, creating a look of soft shadows. We use a post-processing screenspace-based approach, which is applied to a scene after it has been rendered.

glTF model, courtesy of noe-3d.at on Sketchfab, rendered in CesiumJS with combined lighting effects. Ambient occlusion alone highlights detail in the model’s form. When combined with image-based and directional lighting, we can approximate effects similar to a global lighting system without the need for baking lighting or other preprocessing.

As part of this effort, we fixed existing bugs with our screenspace implementation of AO and enabled a new scalable solution for use across a variety of scenarios.

Horizon-based ambient occlusion, or HBAO, uses sampling to determine the minimum angle at which the sky hemisphere is no longer visible from a position. When this is repeated across multiple directions, we have an estimate about the percentage of light in the scene that reaches each pixel. This technique helps visually communicate depth, form, and spatial proximity between objects in the scene, and it can be performed in screenspace for better runtime performance without the need to precompute lighting.

The key improvement made in our implementation was enhanced scalability. While typical AO use cases, like games or architectural visualization, are constrained to one scale, CesiumJS users can travel from outer space to underground in a single app. Previously, the AO parameters had to be configured manually based on trial and error to balance visual appearance with runtime performance. This was inconvenient for anything other than a specific view.

The limitation was the step size used to march along each sampling ray. Rather than using a fixed distance measured in meters, we implemented a normalized Gaussian distribution to scale the sample distance based on the distance from the camera, removing the need for any manual configuration. Occlusion now scales effectively from detailed interiors like pipes in a power plant to large cityscapes like buildings in New York City. Additionally, the falloff is now much smoother: As distance from the camera increases, the shadowed areas become wider, but less dark. In effect, it’s a much closer approximation of how light is occluded in reality.

glTF model, courtesy of noe-3d.at on Sketchfab, rendered in CesiumJS with ambient occlusion only. Scaling the sampling distance ensures views of the model at any scale, by default and without adjusting any settings.

We are committed to continuously pushing the boundaries of what can be achieved with browser-based 3D to provide users with better visualizations. The recent updates to IBL, dynamic environment maps, and ambient occlusion have been a few major steps in that journey.

glTF model showcasing diffuse lighting, courtesy of noe-3d.at on Sketchfab, rendered in CesiumJS before these lighting updates (left, version 1.121) and after (right, version 1.125). The overall effect of the changes is more realistic lighting and more apparent fine details.

Our efforts to enhance the visual quality of CesiumJS are always ongoing. We generated many ideas during this process—like an easier-to-use API for using HDR images and enhancements to how we render shadows—but your feedback is invaluable as we strive to further improve CesiumJS. Check out the Sandcastle example used throughout this blog, and please share your input on visual quality in this community thread.

Leveling Up Lighting in CesiumJS: IBL, Dynamic Environment Maps, and Ambient Occlusion

In January, we shared our code review guide, which we recently created and made available in our new public community repo, celebrated Danny’s Patriot Award from Pennsylvania Employer Support of the Guard and Reserve, and began calling for presentations for the 2025 Cesium Developer Conference. We look forward to seeing you in Philadelphia in June!

CesiumJS 1.126 is now available. Highlights of the release include:

Add ITwinData.loadGeospatialFeatures(iTwinId, collectionId) function to load data from the Geospatial Features API. #12449

Fixed error when resetting Cesium3DTileset.modelMatrix to its initial value. #12409

Fixed the parameter types of the ClippingPolygon.equals function and fixed cases where parameters to equals functions had erroneously not been marked as 'optional'. #12394

Fixed Draco decoding for vertex colors that are normalized UNSIGNED_BYTE or UNSIGNED_SHORT. #12417

Cesium for Unreal v2.13.1 is now available. Highlights of this release include:

Added CesiumUrlTemplateRasterOverlay, allowing a raster overlay to be added using tiles requested based on a specified URL template.

Added EstimateTimeZoneForLongitude method to ACesiumSunSky to set a reasonable TimeZone value at the given longitude.

The "Place Georeference Origin Here" button on ACesiumGeoreference will now adjust the time zone of the ACesiumSunSky instances that reference it, based on the new origin's longitude. This improves user experience when moving the origin to locations where it would be nighttime in the current time zone. A new EstimateTimeZoneForLongitude method on ACesiumSunSky can also be invoked manually from C++ or Blueprint.

Added RequestHeaders property to Cesium3DTileset, and the various Raster Overlay classes, allowing custom headers to be specified.

Worked around a limitation in Unreal's FMatrix -> FTransform conversion that prevented models with a small scale factor (e.g., where vertex positions are expressed in millimeters) from rendering because their scale was treated as 0.0.

Cesium for Unity v1.15.1 is now available. Highlights of this release include:

Exceptions in either C# or C++ code are now handled much more reliably.

Snowdon Sample Model from Autodesk Revit, streamed with 3D Tiles and visualized using Cesium for Unity. Featured in Level 08_CesiumArchitecturalDesign in Cesium for Unity Samples.

Cesium OSM Buildings and Cesium OSM Buildings for Cesium World Bathymetry datasets have been updated based on the OSM Timestamp of Jan 13 00:00 GMT 2025.

In addition to the Bing geocoder, Cesium ion now provides the Google geocoder for use in your applications. See this sandcastle for implementation.

In addition to the Bing geocoder, the Google geocoder is now available to applications using Cesium ion Self-Hosted when your Self-Hosted installation is connected to your Cesium ion SaaS account. See this sandcastle for implementation.

Cesium ion Self-Hosted v1.6.0, including the ability to upload data from Azure for tiling, will be released no later than early March 2025.

Cesium Releases in May 2025

Deep Dive Workshop at the Cesium Developer Conference

Cesium Releases in April 2025

The Weather Company Brings Forecasts to Military Planning with Cesium

Blyncsy Shows Transportation Agencies the Future of Roadway Maintenance with CesiumJS

Cesium Releases in March 2025

Leveling Up Lighting in CesiumJS: IBL, Dynamic Environment Maps, and Ambient Occlusion