Blender 5.1.1

What's new in this version:

Rendering:
El Rey Cast:
- The new Raycast node allows you to cast rays against scene geometry
- Similar to the existing Geometry Nodes node but now available for shaders in both Cycles and EEVEE
- This enables a wide range of effects, including NPR stylization integrated with scene shading. When using EEVEE, it is currently limited to screen-space tracing.

Eevee & viewport:
Quick Start:
- EEVEE materials now compile faster by precompiling GPU pipelines in parallel
- GPU shaders also compile more quickly across all platforms thanks to preprocessing of the shader sources

Memory Savings:
- Memory is getting expensive these days, so it might as well multitask
- EEVEE now saves texture memory by overlapping framebuffer and render textures at different points within a frame

MORE EEVEE & VIEWPORT:
- Control Light Path intensity
- Theme major grid lines
- Better planar reflections
- Performance timing statistics overlay
- Improved grid performance and occlusion
- Higher max AOV
- Support for Light Path node in World
- Improved Reference Spheres handling and space lighting
- Improved Quad View

Blender 5.1 delivers a major boost to animation playback performance:
Shape Keys:
- Shape Key evaluation has seen a significant performance boost since Blender 5.0, especially on high-poly meshes
- All tests are an average time per frame when playing back. The tests were run on a 12 core 24 thread CPU (AMD Ryzen 9 9900X) on Linux. For benchmarks on different systems see the daily benchmarks.

Actions:
- Actions now evaluate much faster now, especially on armatures with many bones keyed
- These tests were done with an armature of 2600 bones that are keyed for ~1000 frames

Smooth Sailing:
- Meet “Smooth (Gaussian)“, a new F-curve modifier to reduce detail and noise in a curve, the same operation as the Smooth operator, but in a non-destructive way

Be Precise:
- When “Show Subframes” is enabled, decimal values for frames will be displayed in the playhead

Color Match:
- Quickly see the interpolation type between keyframes at a glance
- Interpolation lines in the Dope Sheet are now colored to indicate their type, matching the theme colors used by the corresponding icons

More animation:
General:
- Replace actions on multiple objects

Shape Keys:
- New: “Apply to Basis” applies the deformations of selected shape keys to the Basis and then removes them

Rigging:
- Loop selection is now possible in Weight Paint mode when using Vertex Selection

Python API:
- ANIM_OT_convert_legacy_action has been removed since all actions are automatically layered

I/O:
OpenUSD:
- Improved UsdPreviewSurface import/export with support for transparency and translucency
- UsdUIAccessibilityAPI support for authoring and loading on all data-block types that allow Custom Properties
- Mesh export now writes indexed UV coordinates, enabling UV island connectivity reconstruction in other apps
- Python Hooks (Export): New get_prim_map API in on_export, providing a mapping between Blender objects and created USD prims

glTF:
- Import: Fix crash when missing GPU instancing properties
- Export: Fix light normalization
- Export: Fix light temperature conversion
- Export: Fix alpha animation with KHR_animation_pointer

FBX:
- Export shapekey normals when base normals are enabled, fixing some game engine import issues.

Images:
- New: Support for AV1 Image File Format (AVIF)
- JPEG 2000: Use multi-threading to speed up file saving
- OpenEXR: New lossless encoding option HTJ2K

Video & Audio Output:
- Video encoding now allows “Custom” quality level by manually specified ffmpeg CRF value
- Audio bitrate can be set to higher values than 384kb/s now

Stability is a feature:

Winter of Quality:
- During the past December-January, similar to last year, Blender developers focused on improving quality of the code base and overall stability through a coordinated effort called the “Winter of Quality.”
- More than 350 reported issues were fixed. Additionally, developers worked on addressing technical debt, as well as improving documentation

Smooth Dat Form:
- The new “Mask to SDF” node lets you turn any image or shape into signed distance fields
- It’s time to revisit those masks

MORE COMPOSITOR:
- Mix Node now properly mixes alpha
- Relative To Pixel now works with non-single values
- Group Input up to 30% faster in some cases
- New Compositor workspace layout
- Glare, Directional Blur, Lens Distortion, Anti-Alias, Blur, and Vector Blur up to 2x faster
- Image and File Output nodes now read/write custom metadata
- Group now performs implicit input/output conversions
- File Output allows specifying directories again
- Improved Movie Distortion handle of image display window
- Viewer Region has been temporarily hidden