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

Cesium for Omniverse v0.24.0

Cesium for Unity Samples v1.15.5

CesiumJS 1.128

Cesium for Unreal

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

NASA calls the Moon “a treasure trove of science.” 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.

Cesium Moon Terrain in XOSS supporting NASA’s Advanced Operations Concepts Lab. Courtesy Buendea and NAOCL. 

Buendea uses Cesium Moon Terrain to support NASA's Advanced Operations Concepts Lab, specifically the Artemis missions.

Buendea XOSS

Scientific discovery around life off Earth—rock samples and water, for example—will require specific tools and training. XR Operations Support System (XOSS) is a collaboration between Buendea and NAOCL, based out of Johnson Space Center (JSC) in Houston, Texas, USA, to train astronauts in an accurate 3D lunar environment. 

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. In VR mode, astronauts learn to board rovers, use tools to repair equipment, and work together. Admins running the sessions can trigger equipment failures or weather events to provide safe, repeatable learning experiences. 

Buendea and NAOCL provide XOSS for other facilities to work with as a tool to integrate into their workflows for training and simulation. NASA Assessments of Physiology in Cognition for Hybrid Reality Environments (APACHE) carries out human performance studies using XOSS to prepare astronauts for traverses on the Moon, measuring biometric data and other outputs from these moonwalks. Crew Health and Performance Exploration Analog (CHAPEA) and Human Exploration Research Analog (HERA) are both habitat environments at JSC that use XOSS to carry out analog simulated activities for Moon and Mars surface operations. Other groups use XOSS as a digital twin to carry out ad-hoc or science activities for extravehicular activity and intravehicular activity (EVA/IVA). 

Buendea was an early adopter of Cesium Moon Terrain and has used this geospatial base since its August 2024 release. 

XOSS in VR mode. Courtesy Buendea and NAOCL.

Buendea founder Julian Reyes shared that the requirement from NASA was a platform that would deliver the entirety of the Moon in Unreal Engine. Reyes and his team were prepared to build a model of the Moon themselves. Today, XOSS accesses Cesium Moon Terrain via Cesium ion and Cesium for Unreal. 

“By integrating Cesium Moon Terrain into our Unreal XOSS project, we were able to stand up our base integration of the lunar deployment instantly. This enabled us to start with developing and adding in our high-resolution surface terrain tiles directly into the deployment—and effectively cut our development time by more than 50%,” said Reyes, who will present XOSS at the 2025 Cesium Developer Conference. 

Cesium Moon Terrain is the first complete, accurate, and readily accessible 3D dataset of the Moon. Served as 3D Tiles via Cesium ion, it enables visualization, simulation, and analysis for advanced digital twin creation. 

XOSS currently accesses Cesium Moon Terrain via Cesium ion SaaS. In the near future, the platform will run internally at NASA via Cesium ion Self-Hosted to meet strict security requirements and enable a common workspace as more prototyping is done within XOSS. Buendea connects Cesium ion to its Unreal Engine projects via the open source Cesium for Unreal plugin, pulling in real-world content so astronauts learn among the terrain they expect to see. 

With an accurate lunar base already deployed, Buendea’s developers have been able to focus their time on incorporating additional surface data, including topographic images from the Lunar Orbiter Laser Altimeter (LOLA) and photogrammetry of sample rocks from the Apollo missions; adding accurate physics for dispersing regolith on moon when driving; integrating AI for robotics support and geological identification; and modifying lighting to accurately reflect the elongated shadows the lunar South Pole experiences. Fusing graphics capabilities and validated data from many sources in one platform means collaborating groups get a comprehensive view and can prototype and design within XOSS, all on top of Cesium Moon Terrain. 

XOSS users can immerse themselves in nine potential landing and habitation sites near the lunar South Pole. Courtesy Buendea and NAOCL.

Buendea plans to deploy XOSS internally at NASA, among commercial partners, and publicly, for open community development toward our shared future of human spaceflight. 

Both Buendea and Cesium are at the 40th Space Symposium in Colorado Springs this week, April 7-10, 2025. Meet us in booth #628. 

To add Cesium Moon Terrain to your Cesium for Unreal projects, follow this guide. 

Buendea Supports NASA Advanced Operations Concepts Lab with Cesium Moon Terrain 

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.

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 1.128 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. 

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

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. 

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

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 

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

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 

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. 

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.

DroneDeploy enables stakeholders to examine the entire life cycle of a project with its drone software and viewer, which use 3D Tiles and Cesium ion Self-Hosted to make massive photogrammetry datasets manageable and accessible. With Cesium’s 3D Tiling Pipeline, DroneDeploy puts its engineering resources into its custom viewer rather than model processing, and users get photorealistic 3D models for decisions based on reality.

Capture high-resolution aerial data to align teams and keep AEC projects on track. Courtesy DroneDeploy.

DroneDeploy Map Engine

Code review is at the heart of what we do at Cesium. In this blog we discuss core principles around our review process and introduce our code review guide, which we recently created and made available in our new public community repo. At Cesium we maintain multiple open source repositories, most notably our runtime libraries for visualizing geospatial graphics on the web (CesiumJS) and via native engines (Cesium Native, Cesium for Unreal, Cesium for Unity, and Cesium for Omniverse), and since 2012 we have been making monthly releases of these libraries. CesiumJS alone has close to 250,000 lines of source code and 280,000 lines of test code. We also maintain Cesium ion SaaS and Cesium ion Self-Hosted, platforms for tiling, hosting, and streaming 3D geospatial data as 3D Tiles. To top it off, Cesium projects are built collaboratively between the community and the core team, with more than 300 external contributors committing source code to CesiumJS and dozens contributing commits to our native runtimes. 

Maintaining projects at this scale and in open source is not possible without strong engineering processes. Pull requests (PRs) and code reviews—more than most any other engineering process—are where rules are enforced and culture is built. Cesium has structured our guide to reinforce the core values of our engineering teams: Enhance code quality and consistency, streamline collaboration, facilitate knowledge sharing, and foster shared ownership. You may notice our guide doesn’t drill deep into language and framework-specific practices; we designed it as an overarching framework that can be augmented with specific tooling or style guides for our individual projects.

Here are the key principles at work in our guide. 

Tone: Seek great code and motivated people

We often say, "comments are about the code, not the people." We believe review comments are positive opportunities to discuss and improve. Our guide suggests using guiding questions and presenting evidence. Questions invite discussion and are a more gentle way to suggest changes. Every suggestion should be able to link to an authoritative source, like the project's coding guide, rather than relying on the reviewer's opinion. Empathy on the reviewer's part can go a long way toward keeping the contributor motivated in the review process.


Code review cannot happen without well organized projects, and we lean heavily on Git to organize our engineering projects. Git branches and branch protection rules enable collaboration and help us avoid forcing work in progress upon others before it's ready. Our guide advises keeping branches as focused as possible, avoiding mixing large-scale, cross-cutting changes with other changes. We suggest breaking complex changes into a sequence of smaller pull requests, each of which builds upon the previous. Lastly, we caution to avoid rebasing to preserve a usable version history.


Open timely and scoped PRs that create a historical record

We believe PRs should be small, targeted, and atomic. The PR author should create tasks lists covering and linking to all additional work required before merging. Team members should start code review and respond promptly (within 24 hours) to maintain momentum and investment from the author. Pull requests serve as a historical record of a change, so it is important to document the context of the pull request to help preserve it for future reference. The author should include why the change is being made and the test plan with steps and configuration needed to verify the change. Linking is an effective tool for documenting context: We create links to relevant issues (in the current repository or other projects), community forum posts or support threads, standards or API documentation, changelogs for dependencies, and best practices, such as blogs or guides.


Communicate status with automation, CI, and GitHub tooling

No matter the project, our guide advises using Github Actions workflows as part of continuous integration (CI) processes to enforce style guidelines through linting, code quality through unit tests and code scanning, and security through secrets checking and vulnerability scanning. The specific implementations of these checks depend entirely on the language and other features of the project, but automating them, as our guide recommends, streamlines and strengthens the code review process. The reviewer should ensure all checks pass and check artifacts for each stage to ensure that there are no “silent failures.”

Reviewers should maintain velocity by being concise and direct in their comments, avoiding the temptation to expand scope of the PR, and always trying to level up the team by providing impactful feedback that will then be sought after by other engineers. Our guide provides an overview of the critical areas a reviewer should look at before approving a PR, including design, execution, performance, complexity, third-party libraries, style, tests, and documentation of the code changes. 

Approving and merging a pull request means that the reviewer is accepting some responsibility for the code being merged. The author of the code is still largely accountable for any critical issues that immediately arise, but the reviewer shares some accountability as well. In practice, reviews differ by level of toughness depending on the change, which we thought was valuable to break as follows:

Rubber stamp: suitable for pull requests that only deal with documentation.

Skim the code and ensure all CI automation is passing: suitable for small pull requests.

Compile locally and run the code: suitable for most pull requests.

Deep read of the code changes: suitable for most large pull requests.

Synchronously review one-to-one with the author: suitable for giant pull requests.

Lastly, reviews should be public. If the reviewer and author meet in a video call or in a room, the reviewer should summarize the discussion in a PR comment. This helps everyone looking at the PR later and ensures we are transparent about the life of the PR.

Our guide calls out important steps embedded in our code review process for maintaining consistency and usability of our public APIs. Changelogs and release notes should provide clear and open communication about project updates, while also managing user expectations and promoting new features. The code review should ensure the PR meets the following expectations critical for public facing APIs:

Have a versioning strategy: If the changes are significant or potentially break backward compatibility, verify that the project is prepared for a version bump in accordance with its versioning strategy, e.g., according to semantic versioning principles.

Highlight deprecations and breaking changes: Clearly mark any deprecations or breaking changes in the PR description.

It is sometimes necessary to reject a pull request, in particular to maintain the project’s scope. When doing so, first begin with thanks and acknowledge the contributor’s needs as valid, even if the contribution doesn’t align with the project’s goals. Then be clear and constructive about why the PR does not fit with the project. Following that, present the author with ways out, such as a workaround or forking the repo. And finally, encourage them to contribute again in the future.  

Our code review guide is a living document that can be edited and expanded as needed, so it can and will change over time. Cesium has designed our guide to be a forward-looking overarching framework, which can then be implemented as specific guides for individual projects. 

We invite anyone to open issues with feedback or submit PRs with suggestions about our new guide in our community repo, which houses the guide on GitHub.

Building Culture and Community with Code Reviews

In December, we announced the release of the Cesium Design Tiler and Cesium ion for Autodesk Revit Add-In and dug into Reality Tiler v2. Did you keep an eye on Saint Nick with NORAD Tracks Santa on Christmas Eve?

The Cesium Design Tiler and Cesium ion for Autodesk Revit Add-In are now available.

Cesium Design Tiler

CesiumJS 1.125 is now available. Highlights of the release include:

Expanded the integration with the iTwin Platform to load GeoJSON and KML data from the Reality Management API. Use ITwinData.createDataSourceForRealityDataId(iTwinId, realityDataId) to load data as the corresponding Data Source. #12344

Added environmentMapOptions to ModelGraphics. For performance reasons, the environment map will not update if the entity position changes by default. If environment map updates based on entity position are desired, ensure to provide an appropriate environmentMapOptions.maximumPositionEpsilon value. #12358

Reduced memory usage and performance bottlenecks when using environment maps with models. #12356

Fixed JulianDate to always generate valid ISO strings for fractional milliseconds. #12345

Fixed intermittent z-fighting issue. #12337

iTwin Reality Feature Service results displayed as GeoJSON with iTwin Reality Point Cloud data in CesiumJS.

Cesium for Unreal v2.12.0 is now available. Highlights of this release include:

Removed support for Unreal Engine 5.2. Unreal Engine 5.3 or later is now required.

Renamed FCesiumFeatureIdAttribute::GetFeatureIDForVertex to FCesiumFeatureIdAttribute::GetFeatureID.

Renamed FCesiumFeatureIdAttribute::GetVertexCount to FCesiumFeatureIdAttribute::GetCount.

Added support for metadata querying and styling on instanced models.

Fixed a bug in CesiumSubLevelSwitcherComponent that could prevent all sub-levels from loading if a single sub-level failed to load.

This release updates cesium-native from v0.42.0 to v0.43.0. See the changelog for a complete list of changes in cesium-native.

Cesium for Unity v1.14.1 is now available. This is the last release of Cesium for Unity that will support Unity 2021 LTS (2021.3). Future versions will require Unity 2022 LTS (2022.3) or Unity 6.

Fixed a bug that could cause a crash on AppDomain reloads.

Fixed a bug that could cause a crash or incorrect textures when multiple Cesium3DTileset tiles referenced the same image by URL.

Fixed a bug that could cause incorrect colors in a model that did have vertex colors but did not have normals.

Fixed a bug that could cause a hang when attempting to load a model with UINT16 indices where generating flat normals required more than 2^16 vertices.

Fixed a bug in the Abseil vcpkg overlay port that could cause linker errors on some systems.

The new Cesium Design Tiler tiles IFC and glTF models into 3D Tiles. Read more.

The Cesium ion for Autodesk Revit Add-In is available on the Downloads page. This Add-In uploads your current 3D View directly to Cesium ion and tiles it with the Design Tiler to produce 3D Tiles.

Cesium Stories now include annotation features for points, polygons, and polylines. Check out an example here.

The new Design Tiler is now available in the Self-Hosted UI as well as the Self-Hosted CLI.

Cesium ion Self-Hosted has been updated to include more secure container-based images. This is part of a continuing effort to increase the security of the Self-Hosted version of Cesium ion.

Exposed the double-sided option for 3D Models and 3D Capture on the CLI.

Exposed a new option useCrsOrdering on the CityGML Tiler.

Deep Dive Workshop at the Cesium Developer Conference

Buendea Supports NASA Advanced Operations Concepts Lab with Cesium Moon Terrain

Cesium Releases in April 2025

The Weather Company Brings Forecasts to Military Planning with Cesium

Cesium Releases in March 2025

Cesium Releases in February 2025

Building Culture and Community with Code Reviews