Embree is a collection of high-performance ray tracing kernels, developed at Intel. The target user of Embree are graphics application engineers that want to improve the performance of their application by leveraging the optimized ray tracing kernels of Embree. The kernels are optimized for photo-realistic rendering on the latest Intel® processors with support for SSE, AVX, AVX2, and AVX512. Embree supports runtime code selection to choose the traversal and build algorithms that best matches the instruction set of your CPU. We recommend using Embree through its API to get the highest benefit from future improvements. Embree is released as Open Source under the Apache 2.0 license.
Embree supports applications written with the Intel SPMD Program Compiler (ISPC, https://ispc.github.io/) by also providing an ISPC interface to the core ray tracing algorithms. This makes it possible to write a renderer in ISPC that leverages SSE, AVX, AVX2, and AVX512 without any code change. ISPC also supports runtime code selection, thus ISPC will select the best code path for your application, while Embree selects the optimal code path for the ray tracing algorithms.
Embree contains algorithms optimized for incoherent workloads (e.g. Monte Carlo ray tracing algorithms) and coherent workloads (e.g. primary visibility and hard shadow rays). For standard CPUs, the single-ray traversal kernels in Embree provide the best performance for incoherent workloads and are very easy to integrate into existing rendering applications. For AVX512 enabled machines, a renderer written in ISPC using the default hybrid ray/packet traversal algorithms have shown to perform best, but requires writing the renderer in ISPC. In general for coherent workloads, ISPC outperforms the single ray mode on each platform. Embree also supports dynamic scenes by implementing high performance two-level spatial index structure construction algorithms.
In addition to the ray tracing kernels, Embree provides some tutorials to demonstrate how to use the Embree API. The example photorealistic renderer that was originally included in the Embree kernel package is now available in a separate GIT repository (see Embree Example Renderer).
Embree Presentation at SIGGRAPH 2016
Embree Presentation at SIGGRAPH 2015
Embree Paper Talk at SIGGRAPH 2014
Embree Tutorial at SIGGRAPH 2014
Embree 2.0 Presentation at SIGGRAPH 2013
Embree 1.1 Presentation at SIGGRAPH 2012
Blogs / Forum
Read the Embree Blog for more details about Embree.
Participate in Embree Forum Discussion.
Contributing to Embree
To contribute code to the Embree repository you need to sign a Contributor License Agreement (CLA). Individuals need to fill out the Individual Contributor License Agreement (ICLA). Corporations need to fill out the Corporate Contributor License Agreement (CCLA) and each employee that wants to contribute has to fill out an Individual Contributor License Agreement (ICLA). Please follow the instructions of the CLA forms to send them.
Embree Support and Contact
If you encounter bugs please report them via Embree’s GitHub Issue Tracker.
For questions please write us at email@example.com.
To receive notifications of updates and new features of Embree please subscribe to the Embree mailing list.
New Features in Embree 2.14.0
ignore_config_filesoption to init flags that allows the application to ignore Embree configuration files.
- Face-varying interpolation is now supported for subdivision surfaces.
- Up to 16 user vertex buffers are supported for vertex attribute interpolation.
rtcSetBoundaryModefunction, please use the new
RTC_SUBDIV_PIN_BOUNDARYmode for handling boundaries of subdivision meshes.
RTC_SUBDIV_PIN_ALLmode to enforce linear interpolation for subdivision meshes.
- Optimized object generation performance for dynamic scenes.
- Reduced memory consumption when using lots of small dynamic objects.
- Fixed bug for subdivision surfaces using low tessellation rates.
- Hair geometry now uses a new ribbon intersector that intersects with ray-facing quads. The new intersector also returns the v-coordinate of the hair intersection, and fixes artefacts at junction points between segments, at the cost of a small performance hit.
rtcSetBuffer2function, that additionally gets the number of elements of a buffer. In dynamic scenes, this function allows to quickly change buffer sizes, making it possible to change the number of primitives of a mesh or the number of crease features for subdivision surfaces.
- Added simple ‘viewer_anim’ tutorial for rendering key frame animations and ‘buildbench’ for measuring BVH (re-)build performance for static and dynamic scenes.
- Added more AVX512 optimizations for future architectures.
New Features in Embree 2.13.0
- Improved performance for compact (but not robust) scenes.
- Added robust mode for motion blurred triangles and quads.
- Added fast dynamic mode for user geometries.
- Up to 20% faster BVH build performance on the second generation Intel® Xeon Phi™ processor codenamed Knights Landing.
- Improved quality of the spatial split builder.
- Improved performance for coherent streams of ray packets (SOA layout), e.g. for fast primary visibility.
- Various bug fixes in tessellation cache, quad-based spatial split builder, etc.
New Features in Embree 2.12.0
- Added support for multi-segment motion blur for all primitive types.
- API support for stream of pointers to single rays (
- Improved BVH refitting performance for dynamic scenes.
- Improved high-quality mode for quads (added spatial split builder for quads)
- Faster dynamic scenes for triangle and quad-based meshes on AVX2 enabled machines.
- Performance and correctness bugfix in optimization for streams of coherent (single) rays.
- Fixed large memory consumption (issue introduced in Embree v2.11.0). If you use Embree v2.11.0 please upgrade to Embree v2.12.0.
- Reduced memory consumption for dynamic scenes containing small meshes.
- Added support to start and affinitize TBB worker threads by passing “
rtcNewDevice. These settings are recommended on systems with a high thread count.
rtcInterpolate2can now be called within a displacement shader.
- Added initial support for Microsoft’s Parallel Pattern Library (PPL) as tasking system alternative (for optimal performance TBB is highly recommended).
- Updated to TBB 2017 which is released under the Apache v2.0 license.
- Dropped support for Visual Studio 2012 Win32 compiler. Visual Studio 2012 x64 is still supported.
New Features in Embree 2.11.0
- Improved performance for streams of coherent (single) rays flagged with
RTC_INTERSECT_COHERENT. For such coherent ray streams, e.g. primary rays, the performance typically improves by 1.3–2×.
- New spatial split BVH builder for triangles, which is 2–6× faster than the previous version and more memory conservative.
- Improved performance and scalability of all standard BVH builders on systems with large core counts.
rtcGetBoundsfor motion blur scenes.
- Thread affinity is now on by default when running on the latest Intel® Xeon Phi™ processor.
- Added AVX512 support for future Intel® Xeon processors.
New Features in Embree 2.10.0
- Added a new curve geometry which renders the sweep surface of a circle along a Bézier curve.
- Intersection filters can update the
- Geometry types can get disabled at compile time.
- Modified and extended the ray stream API.
- Added new callback mechanism for the ray stream API.
- Improved ray stream performance (up to 5–10%).
- Up to 20% faster morton builder on machines with large core counts.
- Lots of optimizations for the second generation Intel® Xeon Phi™ processor codenamed Knights Landing.
- Added experimental support for compressed BVH nodes (reduces node size to 56–62% of uncompressed size). Compression introduces a typical performance overhead of ~10%.
- Bugfix in backface culling mode. We do now properly cull the backfaces and not the frontfaces.
- Feature freeze for the first generation Intel® Xeon Phi™ coprocessor codenamed Knights Corner. We will still maintain and add bug fixes to Embree v2.9.0, but Embree 2.10 and future versions will no longer support it.
New Features in Embree 2.9.0
- Improved shadow ray performance (10–100% depending on the scene).
- Added initial support for ray streams (10–30% higher performance depending on ray coherence in the stream).
- Added support to calculate second order derivatives using the
- Changed the parametrization for triangular subdivision faces to the same scheme used for pentagons.
- Added support to query the Embree configuration using the
New Features in Embree 2.8.1
- Added support for setting per geometry tessellation rate (supported for subdivision and Bézier geometries).
- Added support for motion blurred instances.
New Features in Embree 2.8.0
- Added support for line segment geometry.
- Added support for quad geometry (replaces triangle-pairs feature).
- Added support for linear motion blur of user geometries.
- Improved performance through AVX512 optimizations.
- Improved performance of lazy scene build (when using TBB 4.4 update 2).
- Improved performance through huge page support under linux.
New Features in Embree 2.7.1
- Internal tasking system supports cancellation of build operations.
- ISPC mode for robust and compact scenes got significantly faster (implemented hybrid traversal for bvh4.triangle4v and bvh4.triangle4i).
- Hair rendering got faster as we fixed some issues with the SAH heuristic cost factors.
- BVH8 got slight faster for single ray traversal (improved sorting when hitting more than 4 boxes).
- BVH build performance got up to 30% faster on CPUs with high core counts (improved parallel partition code).
- High quality build mode again working properly (spatial splits had been deactivated in v2.7.0 due to some bug).
- Support for merging two adjacent triangles sharing a common edge into a triangle-pair primitive (can reduce memory consumption and BVH build times by up to 50% for mostly quad-based input meshes).
- Internal cleanups (reduced number of traversal kernels by more templating)
- Reduced stack size requirements of BVH builders.
- Fixed crash for dynamic scenes, triggered by deleting all geometries from the scene.
New Features in Embree 2.7.0
- Added device concept to Embree to allow different components of an application to use Embree without interfering with each other.
- Fixed memory leak in twolevel builder used for dynamic scenes.
- Fixed bug in tesselation cache that caused crashes for subdivision surfaces.
- Fixed bug in internal task scheduler that caused deadlocks when using
- Improved hit-distance accuracy for thin triangles in robust mode.
- Added support to disable ray packet support in cmake.
New Features in Embree 2.6.2
- Fixed bug triggered by instantiating motion blur geometry.
- Fixed bug in hit UV coordinates of static subdivision geometries.
- Performance improvements when only changing tessellation levels for subdivision geometry per frame.
- Added ray packet intersectors for subdivision geometry, resulting in improved performance for coherent rays.
- Reduced virtual address space usage for static geometries.
- Fixed some AVX2 code paths when compiling with GCC or Clang.
- Bugfix for subdiv patches with non-matching winding order.
- Bugfix in ISA detection of AVX512.
New Features in Embree 2.6.1
- Major performance improvements for ray tracing subdivision surfaces, e.g. up to 2× faster for scenes where only the tessellation levels are changing per frame, and up to 3× faster for scenes with lots of crease features
- Initial support for architectures supporting the new 16-wide AVX512 ISA
- Implemented intersection filter callback support for subdivision surfaces
RTC_IGNORE_INVALID_RAYSCMake option which makes the ray intersectors more robust against full tree traversal caused by invalid ray inputs (e.g. INF, NaN, etc)
New Features in Embree 2.6.0
rtcInterpolatefunction to interpolate per vertex attributes
rtcSetBoundaryModefunction that can be used to select the boundary handling for subdivision surfaces
- Fixed a traversal bug that caused rays with very small ray direction components to miss geometry
- Performance improvements for the robust traversal mode
- Fixed deadlock when calling
rtcCommitfrom multiple threads on same scene
New Features in Embree 2.5.1
- On dual socket workstations, the initial BVH build performance almost doubled through a better memory allocation scheme
- Reduced memory usage for subdivision surface objects with crease features
rtcCommitperformance is robust against unset “flush to zero” and “denormals are zero” flags. However, enabling these flags in your application is still recommended
- Reduced memory usage for subdivision surfaces with borders and infinitely sharp creases
- Lots of internal cleanups and bug fixes for both Intel® Xeon® and Intel® Xeon Phi™
New Features in Embree 2.5.0
- Improved hierarchy build performance on both Intel Xeon and Intel Xeon Phi
- Vastly improved tessellation cache for ray tracing subdivision surfaces
rtcGetUserDataAPI call to query per geometry user pointer set through
- Added support for memory monitor callback functions to track and limit memory consumption
- Added support for progress monitor callback functions to track build progress and cancel long build operations
- BVH builders can be used to build user defined hierarchies inside the application (see tutorial BVH Builder)
- Switched to TBB as default tasking system on Xeon to get even faster hierarchy build times and better integration for applications that also use TBB
rtcCommitcan get called from multiple TBB threads to join the hierarchy build operations
New Features in Embree 2.4
- Support for Catmull Clark subdivision surfaces (triangle/quad base primitives)
- Support for vector displacements on Catmull Clark subdivision surfaces
- Various bug fixes (e.g. 4-byte alignment of vertex buffers works)
New Features in Embree 2.3.3
- BVH builders more robustly handle invalid input data (Intel Xeon processor family)
- Motion blur support for hair geometry (Xeon)
- Improved motion blur performance for triangle geometry (Xeon)
- Improved robust ray tracing mode (Xeon)
rtcCommitThreadAPI call for easier integration into existing tasking systems (Xeon and Intel Xeon Phi coprocessor)
- Added support for recording and replaying all
rtcOccludedcalls (Xeon and Xeon Phi)
New Features in Embree 2.3.2
- Improved mixed AABB/OBB-BVH for hair geometry (Xeon Phi)
- Reduced amount of pre-allocated memory for BVH builders (Xeon Phi)
- New 64 bit Morton code-based BVH builder (Xeon Phi)
- (Enhanced) Morton code-based BVH builders use now tree rotations to improve BVH quality (Xeon Phi)
- Bug fixes (Xeon and Xeon Phi)
New Features in Embree 2.3.1
- High quality BVH mode improves spatial splits which result in up to 30% performance improvement for some scenes (Xeon)
- Compile time enabled intersection filter functions do not reduce performance if no intersection filter is used in the scene (Xeon and Xeon Phi)
- Improved ray tracing performance for hair geometry by >20% on Xeon Phi. BVH for hair geometry requires 20% less memory
- BVH8 for AVX/AVX2 targets improves performance for single ray tracing on Haswell by up to 12% and by up to 5% for hybrid (Xeon)
- Memory conservative BVH for Xeon Phi now uses BVH node quantization to lower memory footprint (requires half the memory footprint of the default BVH)
New Features in Embree 2.3
- Support for ray tracing hair geometry (Xeon and Xeon Phi)
- Catching errors through error callback function
- Faster hybrid traversal (Xeon and Xeon Phi)
- New memory conservative BVH for Xeon Phi
- Faster Morton code-based builder on Xeon
- Faster binned-SAH builder on Xeon Phi
- Lots of code cleanups/simplifications/improvements (Xeon and Xeon Phi)
New Features in Embree 2.2
- Support for motion blur on Xeon Phi
- Support for intersection filter callback functions
- Support for buffer sharing with the application
- Lots of AVX2 optimizations, e.g. ~20% faster 8-wide hybrid traversal
- Experimental support for 8-wide (AVX/AVX2) and 16-wide BVHs (Xeon Phi)
New Features in Embree 2.1
- New future proof API with a strong focus on supporting dynamic scenes
- Lots of optimizations for 8-wide AVX2 (Haswell architecture)
- Automatic runtime code selection for SSE, AVX, and AVX2
- Support for user-defined geometry
- New and improved BVH builders:
- Fast adaptive Morton code-based builder (without SAH-based top-level rebuild)
- Both the SAH and Morton code-based builders got faster (Xeon Phi)
- New variant of the SAH-based builder using triangle pre-splits (Xeon Phi)
Example Performance Numbers for Embree 2.1
BVH rebuild performance (including triangle accel generation, excluding memory allocation) for scenes with 2–12 million triangles:
- Intel® Core™ i7 (Haswell-based CPU, 4 cores @ 3.0 GHz)
- 7–8 million triangles/s for the SAH-based BVH builder
- 30–36 million triangles/s for the Morton code-based BVH builder
- Intel® Xeon Phi™ 7120
- 37–40 million triangles/s for the SAH-based BVH builder
- 140–160 million triangles/s for the Morton code-based BVH builder
Rendering of the Crown model (
crown.ecs) with 4 samples per pixel (
- Intel® Core™ i7 (Haswell-based CPU, 4 cores CPU @ 3.0 GHz)
- 1024×1024 resolution: 7.8 million rays per sec
- 1920×1080 resolution: 9.9 million rays per sec
- Intel® Xeon Phi™ 7120
- 1024×1024 resolution: 47.1 million rays per sec
- 1920×1080 resolution: 61.1 million rays per sec
New Features in Embree 2.0
- Support for the Intel® Xeon Phi™ coprocessor platform
- Support for high-performance “packet” kernels on SSE, AVX, and Xeon Phi
- Integration with the Intel® SPMD Program Compiler (ISPC)
- Instantiation and fast BVH reconstruction
- Example photo-realistic rendering engine for both C++ and ISPC
This software is based in part on the work of the Independent JPEG Group.