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High Performance Ray Tracing Kernels

Embree Overview

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 the 16-wide Intel® Xeon Phi™ coprocessor vector instructions. 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 Programm Compiler (ISPC, 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 Xeon Phi instructions 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 Xeon Phi, 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).

Version History

New Features in Embree 2.5.0

New Features in Embree 2.4

New Features in Embree 2.3.3

New Features in Embree 2.3.2

New Features in Embree 2.3.1

New Features in Embree 2.3

New Features in Embree 2.2

New Features in Embree 2.1

Example Performance Numbers for Embree 2.1

BVH rebuild performance (including triangle accel generation, excluding memory allocation) for scenes with 2–12 million triangles:

Rendering of the Crown model (crown.ecs) with 4 samples per pixel (-spp 4):

New Features in Embree 2.0

Embree Resources


Exploiting Local Orientation Similarity for Efficient Ray Traversal of Hair and Fur
Sven Woop, Carsten Benthin, Ingo Wald, Gregory S. Johnson, and Eric Tabellion
High Performance Graphics 2014
[pdf], [pptx]

Embree – A Kernel Framework for Efficient CPU Ray Tracing
Ingo Wald, Sven Woop, Carsten Benthin, Gregory S. Johnson, and Manfred Ernst
ACM Transactions on Graphics (proceedings of ACM SIGGRAPH) 2014
[pdf], [bib]

Watertight Ray/Triangle Intersection
Sven Woop, Carsten Benthin, Ingo Wald
Journal of Computer Graphics Techniques (JCGT), Volume 2, Issue 1, pages 65–82, 2013.
[pdf], [bib]

Combining Single and Packet-Ray Tracing for Arbitrary Ray Distributions on the Intel MIC Architecture
Carsten Benthin, Ingo Wald, Sven Woop, Manfred Ernst, William R. Mark
IEEE Transactions on Visualization and Computer Graphics, Volume 18, Issue 9, 2012
[pdf], [bib]

Fast Construction of SAH BVHs on the Intel Many Integrated Core (MIC) Architecture
Ingo Wald
IEEE Transactions on Visualization and Computer Graphics, 18(1), 2012, pages 47–57


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.

Embree Support and Contact

If you encounter bugs please report them via Embree’s GitHub Issue Tracker.

For questions please write us at

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