Greetings Residents!
Over the next several weeks PBR Materials will be rolling out across the grid. For those who do not know what PBR Materials are already, this post will explain what they are, how to use them and the benefits they bring. This announcement is particularly of interest to residents who create inworld objects and avatar attachments. 
PBR stands for Physically Based Rendering. PBR is a richer way of specifying the surface of an object that better simulates how objects appear in real life. PBR allows for realistic lighting for metals, plastics, leather, fabric, and more, including realistic reflections and bounce lighting. The Second Life Viewer will now be able to display these more realistic-appearing objects in world, as well as allow creators to include this more advanced information in the object texturing.
GLTF stands for Graphics Library Transmission Format. This is a standard file format, common in computer graphics, that allows storage of PBR information. GLTF files can be used by many 3D content authoring tools. Second Life will now support the import and export of GLTF files that contain PBR information. Note that at this time only PBR Materials will be imported. Full GLTF support will be available at a later date.
Important note: Until PBR server support is released across the entire Second Life grid, there is a risk of damaging content to which PBR Materials are applied, if rezzed or worn in a region that is not PBR-capable.
At present, you will need to use the latest Second Life release candidate viewer with PBR support 7.0.1.6658224456 and be on PBR capable regions running on BlueSteel and Le Tigre channels with build (2023-10-11.6488746491). To confirm you are using the correct viewer and server, while running Second Life open Help > About Second Life.
What are PBR Materials? Why would I use them in my creations? 
The goal behind PBR Materials is Increased visual realism. One method of enhancing realism is to create scenes with real reflections which mimic how our eyes have learned to identify that a surface is metal versus plastic. The Viewer has always been open source and so we sought an open source solution, GLTF, to achieve this realism. GLTF was created by the Khronos Group https://www.khronos.org/, a standards body responsible for open standards such as OpenGL, OpenXR, Vulkan, and others.
With this new Viewer feature, PBR Materials will automatically generate real reflections when applied to new or existing content. While we cannot go back and add PBR Materials to no-mod content — only the original content creator can — every effort has been made to preserve or improve all object appearances in world. The team has been working with content creators for many months, and we thank them all for their dedication to making Second Life the benchmark for beautiful inworld content.
What if you do not create content?
If you do not create inworld content or avatar attachments, you do not need to do anything as a result of these changes. You will begin to see more realistic reflections and lighting on objects inworld and for sale as creators adopt this new feature.
New Features
The key additions and changes for PBR Materials are:
- GLTF support for PBR Materials
- HDR Environments
- Auto exposure and tonemapping
- The default environment of Second Life has always been a sunny day with blue skies and this will be more apparent now.
- Reflection Probes (automatic and manual)
- Automatically generated by the PBR Viewer
- Manually generated by content creators for interior spaces (requires lighting)
- Materials system folder
Benefits
- GLTF standards are widely accepted and utilized for content creation across many applications
- PBR Materials objectively and subjectively look better
- Real reflections automatically generated by the Viewer
- Increased compatibility with content creation tools e.g. Substance Painter, Blender
There is a wonderful video from Second Life University on our Youtube channel. We encourage anyone wishing to learn more to take a look: How to Create PBR Materials
The Second Life Wiki has more technical information about GLTF PBR Materials and how to use them in the content you create.
Known Issues
While our GLTF PBR Materials project is closer than ever to full release, there are some known issues and we know with broader release, more issues will be uncovered. If you see something, please say something, by filing a BUG report in Jira.
- PBR material information may be lost from content on non-PBR aware regions
- Underwater reflections are weird. We hope to fix this in a future release
- Materials set to alpha mode Blend cannot be changed back to Opaque
- MacOS performance issues
- Poor performance on Apple Silicon when “Reflection Coverage” not set to “None”
- Poor performance on Intel Macbooks when shadows are enabled
- PBR Material limited permissions issues
- Transition lines between overlapping manual probes
- Semi-transparent fullbright objects slightly more opaque
- Non-PBR enabled Viewers will show high packet loss on PBR aware regions due to the introduction of a new message.
There are inworld Content User Group Meetings we encourage you to attend to discuss your questions and give feedback. For more information see Content User Group
IMPORTANT: If content looks good in the Khronos GLTF Sample Viewer or Adobe Substance Painter but looks wrong when you import it into Second Life, please stop and file a bug immediately. Our goal is to adhere to the GLTF specification. Please do not modify content in Second Life to work around situations where the Viewer does not adhere completely to the GLTF spec.
veying complex emotions. In Second Life, artists have created moving installations and interactive experiences that invite users to reflect on the impact of 9/11.