Intel^® OSPRay

A Ray Tracing Based Rendering Engine for High-Fidelity Visualization

Interactive CPU Rendering

OSPRay features interactive CPU rendering capabilities geared toward Scientific Visualization applications. Advanced shading effects such as Ambient Occlusion, shadows, and transparency can be rendered interactively, enabling new insights into data exploration.

Global Illumination

OSPRay includes a path tracer capable of interactively rendering photorealistic global illumination.

Volume Rendering

OSPRay supports high-fidelity interactive direct volume rendering with a number of state of the art features.

MPI Distributed

Run on large scale distributed-memory systems with a high-performance MPI backend. Shown is a 450GB direct numerical simulation data set running interactively at TACC’s Maverick cluster.

Display Walls

OSPRay parallel rendering on TACC’s “Stallion” display wall.

ParaView

OSPRay is directly integrated into ParaView 5.x. Implementations for VisIt, VMD, and other popular tools have also been developed.

Open Source

OSPRay is Open Sourced under the Apache 2.0 license.

OSPRay Overview

Intel® OSPRay is an open source, scalable, and portable ray tracing engine for high-performance, high-fidelity visualization on Intel Architecture CPUs. OSPRay is part of the Intel Rendering Framework and is released under the permissive Apache 2.0 license.

The purpose of OSPRay is to provide an open, powerful, and easy-to-use rendering library that allows one to easily build applications that use ray tracing based rendering for interactive applications (including both surface- and volume-based visualizations). OSPRay is completely CPU-based, and runs on anything from laptops, to workstations, to compute nodes in HPC systems.

OSPRay internally builds on top of Intel Embree and ISPC (Intel SPMD Program Compiler), and fully exploits modern instruction sets like Intel SSE4, AVX, AVX2, and AVX-512 to achieve high rendering performance, thus a CPU with support for at least SSE4.1 is required to run OSPRay.

OSPRay Support and Contact

OSPRay is under active development, and though we do our best to guarantee stable release versions a certain number of bugs, as-yet-missing features, inconsistencies, or any other issues are still possible. Should you find any such issues please report them immediately via OSPRay’s GitHub Issue Tracker (or, if you should happen to have a fix for it,you can also send us a pull request); for missing features please contact us via email at ospray@googlegroups.com.

For recent news, updates, and announcements, please see our complete news/updates page.

Join our mailing list to receive release announcements and major news regarding OSPRay.

Version History

Changes in v1.8.3:

Fix bug where parameters set by ospSet1b() were being ignored
Fix bug in box intersection tests possibly creating NaNs
Fix issue with client applications calling find_package(ospray) more than once
Fix bug in cylinder intersection when ray and cylinder are perpendicular
Fix rare crash in path tracer / MultiBSDF

Changes in v1.8.2:

CMake bug fix where external users of OSPRay needed CMake newer than version 3.1
Fix incorrect propagation of tasking system flags from an OSPRay install
Fix inconsistency between supported environment variables and command line parameters passed to ospInit()
- Missing variables were OSPRAY_LOAD_MODULES and OSPRAY_DEFAULT_DEVICE

Changes in v1.8.1:

CMake bug fix to remove full paths to dependencies in packages

Changes in v1.8.0:

This will be the last minor revision of OSPRay. Future development effort in the devel branch will be dedicated to v2.0 API changes and may break existing v1.x applications.
- This will also be the last version of OSPRay to include ospray_sg and the Example Viewer. Users which depend on these should instead use the separate OSPRay Studio project, where ospray_sg will be migrated.
- We will continue to support patch releases of v1.8.x in case of any reported bugs
Refactored CMake to use newer CMake concepts
- All targets are now exported in OSPRay installs and can be consumed by client projects with associated includes, libraries, and definitions
- OSPRay now requires CMake v3.1 to build
- See documentation for more details
Added new minimal tutorial apps to replace the more complex Example Viewer
Added new “subdivision” geometry type to support subdivision surfaces
Added support for texture formats L8, LA8 (gamma-encoded luminance), and RA8 (linear two component). Note that the enum OSP_TEXTURE_FORMAT_INVALID changed its value, thus recompilation may be necessary.
Automatic epsilon handling, which removes the “epsilon” parameter on all renderers
Normals in framebuffer channel OSP_FB_NORMAL are now in world-space
Added support for Intel® Open Image Denoise to the Example Viewer
- This same integration will soon be ported to OSPRay Studio
Fixed artifacts for scaled instances of spheres, cylinders and streamlines
Improvements to precision of intersections with cylinders and streamlines
Fixed Quadlight: the emitting side is now indeed in direction edge1×edge2

Changes in v1.7.3:

Make sure a “default” device can always be created
Fixed ospNewTexture2D (completely implementing old behavior)
Cleanup any shared object handles from the OS created from ospLoadModule()

Changes in v1.7.2:

Fixed issue in mpi_offload device where ospRelease would sometimes not correctly free objects
Fixed issue in ospray_sg where structured volumes would not properly release the underlying OSPRay object handles

Changes in v1.7.1:

Fixed issue where the Principled material would sometimes show up incorrectly as black
Fixed issue where some headers were missing from install packages

Changes in v1.7.0:

Generalized texture interface to support more than classic 2D image textures, thus OSPTexture2D and ospNewTexture2D are now deprecated, use the new API call ospNewTexture("texture2d") instead
- Added new volume texture type to visualize volume data on arbitrary geometry placed inside the volume
Added new framebuffer channels OSP_FB_NORMAL and OSP_FB_ALBEDO
Applications can get information about the progress of rendering the current frame, and optionally cancel it, by registering a callback function via ospSetProgressFunc()
Lights are not tied to the renderer type, so a new function ospNewLight3() was introduced to implement this. Please convert all uses of ospNewLight() and/or ospNewLight2() to ospNewLight3()
Added sheenTint parameter to Principled material
Added baseNormal parameter to Principled material
Added low-discrepancy sampling to path tracer
The spp parameter on the renderer no longer supports values less than 1, instead applications should render to a separate, lower resolution framebuffer during interaction to achieve the same behavior

Changes in v1.6.1:

Many bug fixes
- Quad mesh interpolation and sampling
- Normal mapping in path tracer materials
- Memory corruption with partly emitting mesh lights
- Logic for setting thread affinity

Changes in v1.6.0:

Updated ispc device to use Embree3 (minimum required Embree version is 3.1)
Added new ospShutdown() API function to aid in correctness and determinism of OSPRay API cleanup
Added “Principled” and "CarPaint" materials to the path tracer
Improved flexibility of the tone mapper
Improvements to unstructured volume
- Support for wedges (in addition to tets and hexes)
- Support for implicit isosurface geometry
- Support for cell-centered data (as an alternative to per-vertex data)
- Added an option to precompute normals, providing a memory/performance trade-off for applications
Implemented “quads” geometry type to handle quads directly
Implemented the ability to set “void” cell values in all volume types: when NaN is present as a volume’s cell value the volume sample will be ignored by the SciVis renderer
Fixed support for color strides which were not multiples of sizeof(float)
Added support for RGBA8 color format to spheres, which can be set by specifying the “color_format” parameter as OSP_UCHAR4, or passing the “color” array through an OSPData of type OSP_UCHAR4.
Added ability to configure Embree scene flags via OSPModel parameters
ospFreeFrameBuffer() has been deprecated in favor of using ospRelease() to free framebuffer handles
Fixed memory leak caused by incorrect parameter reference counts in ispc device
Fixed occasional crashes in the mpi_offload device on shutdown
Various improvements to sample apps and ospray_sg
- Added new generator nodes, allowing the ability to inject programmatically generated scene data (only C++ for now)
- Bug fixes and improvements to enhance stability and usability

Changes in v1.5.0:

Unstructured tetrahedral volume now generalized to also support hexahedral data, now called unstructured_volume
New function for creating materials (ospNewMaterial2()) which takes the renderer type string, not a renderer instance (the old version is now deprecated)
New tonemapper PixelOp for tone mapping final frames
Streamlines now support per-vertex radii and smooth interpolation
ospray_sg headers are now installed alongside the SDK
Core OSPRay ispc device now implemented as a module
- Devices which implement the public API are no longer required to link the dependencies to core OSPRay (e.g., Embree v2.x)
- By default, ospInit() will load the ispc module if a device was not created via --osp:mpi or --osp:device:[name]
MPI devices can now accept an existing world communicator instead of always creating their own
Added ability to control ISPC specific optimization flags via CMake options. See the various ISPC_FLAGS_* variables to control which flags get used
Enhancements to sample applications
- ospray_sg (and thus ospExampleViewer/ospBenchmark) can now be extended with new scene data importers via modules or the SDK
- Updated ospTutorial examples to properly call ospRelease()
- New options in the ospExampleViewer GUI to showcase new features (sRGB framebuffers, tone mapping, etc.)
General bug fixes
- Fixes to geometries with multiple emissive materials
- Improvements to precision of ray-sphere intersections

Changes in v1.4.3:

Several bug fixes
- Fixed potential issue with static initialization order
- Correct compiler flags for Debug config
- Spheres postIntersect shading is now 64-bit safer

Changes in v1.4.2:

Several cleanups and bug fixes
- Fixed memory leak where the Embree BVH was never released when an OSPModel was released
- Fixed a crash when API logging was enabled in certain situations
- Fixed a crash in MPI mode when creating lights without a renderer
- Fixed an issue with camera lens samples not initialized when spp <= 0
- Fixed an issue in ospExampleViewer when specifying multiple data files
The C99 tutorial is now indicated as the default; the C++ wrappers do not change the semantics of the API (memory management) so the C99 version should be considered first when learning the API

Changes in v1.4.1:

Several cleanups and bug fixes
- Improved precision of ray intersection with streamlines, spheres, and cylinder geometries
- Fixed address overflow in framebuffer, in practice image size is now limited only by available memory
- Fixed several deadlocks and race conditions
- Fix shadow computation in SciVis renderer, objects behind light sources do not occlude anymore
- No more image jittering with MPI rendering when no accumulation buffer is used
Improved path tracer materials
- Additionally support RGB eta/k for Metal
- Added Alloy material, a “metal” with textured color
Minimum required Embree version is now v2.15

Changes in v1.4.0:

New adaptive mesh refinement (AMR) and unstructured tetrahedral volume types
Dynamic load balancing is now implemented for the mpi_offload device
Many improvements and fixes to the available path tracer materials
- Specular lobe of OBJMaterial uses Blinn-Phong for more realistic highlights
- Metal accepts spectral samples of complex refraction index
- ThinGlass behaves consistent to Glass and can texture attenuation color
Added Russian roulette termination to path tracer
SciVis OBJMaterial accepts texture coordinate transformations
Applications can now access depth information in MPI distributed uses of OSPRay (both mpi_offload and mpi_distributed devices)
Many robustness fixes for both the mpi_offload and mpi_distributed devices through improvements to the mpi_common and mpi_maml infrastructure libraries
Major sample app cleanups
- ospray_sg library is the new basis for building apps, which is a scene graph implementation
- Old (unused) libraries have been removed: miniSG, command line, importer, loaders, and scripting
- Some removed functionality (such as scripting) may be reintroduced in the new infrastructure later, though most features have remained and have been improved
- Optional improved texture loading has been transitioned from ImageMagick to OpenImageIO
Many cleanups, bug fixes, and improvements to ospray_common and other support libraries
This will be the last release in which we support MSVC12 (Visual Studio 2013). Future releases will require VS2015 or newer

Changes in v1.3.1:

Improved robustness of OSPRay CMake find_package config
- Fixed bugs related to CMake configuration when using the OSPRay SDK from an install
Fixed issue with Embree library when installing with OSPRAY_INSTALL_DEPENDENCIES enabled

Changes in v1.3.0:

New MPI distributed device to support MPI distributed applications using OSPRay collectively for “in-situ” rendering (currently in “alpha”)
- Enabled via new mpi_distributed device type
- Currently only supports raycast renderer, other renderers will be supported in the future
- All API calls are expected to be exactly replicated (object instances and parameters) except scene data (geometries and volumes)
- The original MPI device is now called the mpi_offload device to differentiate between the two implementations
Support of Intel® AVX-512 for next generation Intel® Xeon® processor (codename Skylake), thus new minimum ISPC version is 1.9.1
Thread affinity of OSPRay’s tasking system can now be controlled via either device parameter setAffinity, or command line parameter osp:setaffinity, or environment variable OSPRAY_SET_AFFINITY
Changed behavior of the background color in the SciVis renderer: bgColor now includes alpha and is always blended (no backgroundEnabled anymore). To disable the background do not set bgColor, or set it to transparent black (0, 0, 0, 0)
Geometries “spheres” and “cylinders” now support texture coordinates
The GLUT- and Qt-based demo viewer applications have been replaced by an example viewer with minimal dependencies
- Building the sample applications now requires GCC 4.9 (previously 4.8) for features used in the C++ standard library; OSPRay itself can still be built with GCC 4.8
- The new example viewer based on ospray::sg (called ospExampleViewerSg) is the single application we are consolidating to, ospExampleViewer will remain only as a deprecated viewer for compatibility with the old ospGlutViewer application
Deprecated ospCreateDevice(); use ospNewDevice() instead
Improved error handling
- Various API functions now return an OSPError value
- ospDeviceSetStatusFunc() replaces the deprecated ospDeviceSetErrorMsgFunc()
- New API functions to query the last error (ospDeviceGetLastErrorCode() and ospDeviceGetLastErrorMsg()) or to register an error callback with ospDeviceSetErrorFunc()
- Fixed bug where exceptions could leak to C applications

Changes in v1.2.1:

Various bug fixes related to MPI distributed rendering, ISPC issues on Windows, and other build related issues

Changes in v1.2.0:

Added support for volumes with voxelType short (16-bit signed integers). Applications need to recompile, because OSPDataType has been re-enumerated
Removed SciVis renderer parameter aoWeight, the intensity (and now color as well) of AO is controlled via “ambient” lights. If aoSamples is zero (the default) then ambient lights cause ambient illumination (without occlusion)
New SciVis renderer parameter aoTransparencyEnabled, controlling whether object transparency is respected when computing ambient occlusion (disabled by default, as it is considerable slower)
Implement normal mapping for SciVis renderer
Support of emissive (and illuminating) geometries in the path tracer via new material “Luminous”
Lights can optionally made invisible by using the new parameter isVisible (only relevant for path tracer)
OSPRay Devices are now extendable through modules and the SDK
- Devices can be created and set current, creating an alternative method for initializing the API
- New API functions for committing parameters on Devices
Removed support for the first generation Intel® Xeon Phi™ coprocessor (codename Knights Corner)
Other minor improvements, updates, and bug fixes
- Updated Embree required version to v2.13.0 for added features and performance
- New API function ospDeviceSetErrorMsgFunc() to specify a callback for handling message outputs from OSPRay
- Added ability to remove user set parameter values with new ospRemoveParam() API function
- The MPI device is now provided via a module, removing the need for having separately compiled versions of OSPRay with and without MPI
- OSPRay build dependencies now only get installed if OSPRAY_INSTALL_DEPENDENCIES CMake variable is enabled

Changes in v1.1.2:

Various bug fixes related to normalization, epsilons and debug messages

Changes in v1.1.1:

Fixed support of first generation Intel Xeon Phi coprocessor (codename Knights Corner) and the COI device
Fix normalization bug that caused rendering artifacts

Changes in v1.1.0:

New “scivis” renderer features
- Single sided lighting (enabled by default)
- Many new volume rendering specific features
  - Adaptive sampling to help improve the correctness of rendering high-frequency volume data
  - Pre-integration of transfer function for higher fidelity images
  - Ambient occlusion
  - Volumes can cast shadows
  - Smooth shading in volumes
  - Single shading point option for accelerated shading
Added preliminary support for adaptive accumulation in the MPI device
Camera specific features
- Initial support for stereo rendering with the perspective camera
- Option architectural in perspective camera, rectifying vertical edges to appear parallel
- Rendering a subsection of the full view with imageStart/imageEnd supported by all cameras
This will be our last release supporting the first generation Intel Xeon Phi coprocessor (codename Knights Corner)
- Future major and minor releases will be upgraded to the latest version of Embree, which no longer supports Knights Corner
- Depending on user feedback, patch releases are still made to fix bugs
Enhanced output statistics in ospBenchmark application
Many fixes to the OSPRay SDK
- Improved CMake detection of compile-time enabled features
- Now distribute OSPRay configuration and ISPC CMake macros
- Improved SDK support on Windows
OSPRay library can now be compiled with -Wall and -Wextra enabled
- Tested with GCC v5.3.1 and Clang v3.8
- Sample applications and modules have not been fixed yet, thus applications which build OSPRay as a CMake subproject should disable them with -DOSPRAY_ENABLE_APPS=OFF and -DOSPRAY_ENABLE_MODULES=OFF
Minor bug fixes, improvements, and cleanups
- Regard shading normal when bump mapping
- Fix internal CMake naming inconsistencies in macros
- Fix missing API calls in C++ wrapper classes
- Fix crashes on MIC
- Fix thread count initialization bug with TBB
- CMake optimizations for faster configuration times
- Enhanced support for scripting in both ospGlutViewer and ospBenchmark applications

Changes in v1.0.0:

New OSPRay SDK
- OSPRay internal headers are now installed, enabling applications to extend OSPRay from a binary install
- CMake macros for OSPRay and ISPC configuration now a part of binary releases
  - CMake clients use them by calling include(${OSPRAY_USE_FILE}) in their CMake code after calling find_package(ospray)
- New OSPRay C++ wrapper classes
  - These act as a thin layer on top of OSPRay object handles, where multiple wrappers will share the same underlying handle when assigned, copied, or moved
  - New OSPRay objects are only created when a class instance is explicitly constructed
  - C++ users are encouraged to use these over the ospray.h API
Complete rework of sample applications
- New shared code for parsing the commandline
- Save/load of transfer functions now handled through a separate library which does not depend on Qt
- Added ospCvtParaViewTfcn utility, which enables ospVolumeViewer to load color maps from ParaView
- GLUT based sample viewer updates
  - Rename of ospModelViewer to ospGlutViewer
  - GLUT viewer now supports volume rendering
  - Command mode with preliminary scripting capabilities, enabled by pressing ‘:’ key (not available when using Intel C++ Compiler (icc))
- Enhanced support of sample applications on Windows
New minimum ISPC version is 1.9.0
Support of Intel® AVX-512 for second generation Intel Xeon Phi processor (codename Knights Landing) is now a part of the OSPRAY_BUILD_ISA CMake build configuration
- Compiling AVX-512 requires icc to be enabled as a build option
Enhanced error messages when ospLoadModule() fails
Added OSP_FB_RGBA32F support in the DistributedFrameBuffer
Updated Glass shader in the path tracer
Many miscellaneous cleanups, bug fixes, and improvements

Changes in v0.10.1:

Fixed support of first generation Intel Xeon Phi coprocessor (codename Knights Corner)
Restored missing implementation of ospRemoveVolume()

Changes in v0.10.0:

Added new tasking options: Cilk, Internal, and Debug
- Provides more ways for OSPRay to interact with calling application tasking systems
  - Cilk: Use Intel® Cilk™ Plus language extensions (icc only)
  - Internal: Use hand written OSPRay tasking system
  - Debug: All tasks are run in serial (useful for debugging)
- In most cases, Intel Threading Building Blocks (Intel TBB) remains the fastest option
Added support for adaptive accumulation and stopping
- ospRenderFrame now returns an estimation of the variance in the rendered image if the framebuffer was created with the OSP_FB_VARIANCE channel
- If the renderer parameter varianceThreshold is set, progressive refinement concentrates on regions of the image with a variance higher than this threshold
Added support for volumes with voxelType ushort (16-bit unsigned integers)
OSPTexture2D now supports sRGB formats – actually most images are stored in sRGB. As a consequence the API call ospNewTexture2D() needed to change to accept the new OSPTextureFormat parameter
Similarly, OSPRay’s framebuffer types now also distinguishes between linear and sRGB 8-bit formats. The new types are OSP_FB_NONE, OSP_FB_RGBA8, OSP_FB_SRGBA, and OSP_FB_RGBA32F
Changed “scivis” renderer parameter defaults
- All shading (AO + shadows) must be explicitly enabled
OSPRay can now use a newer, pre-installed Embree enabled by the new OSPRAY_USE_EXTERNAL_EMBREE CMake option
New ospcommon library used to separately provide math types and OS abstractions for both OSPRay and sample applications
- Removes extra dependencies on internal Embree math types and utility functions
- ospray.h header is now C99 compatible
Removed loaders module, functionality remains inside of ospVolumeViewer
Many miscellaneous cleanups, bug fixes, and improvements
- Fixed data distributed volume rendering bugs when using less blocks than workers
- Fixes to CMake find_package() config
- Fix bug in GhostBlockBrickVolume when using doubles
- Various robustness changes made in CMake to make it easier to compile OSPRay

Changes in v0.9.1:

Volume rendering now integrated into the “scivis” renderer
- Volumes are rendered in the same way the “dvr” volume renderer renders them
- Ambient occlusion works with implicit isosurfaces, with a known visual quality/performance trade-off
Intel Xeon Phi coprocessor (codename Knights Corner) COI device and build infrastructure restored (volume rendering is known to still be broken)
New support for CPack built OSPRay binary redistributable packages
Added support for HDRI lighting in path tracer
Added ospRemoveVolume() API call
Added ability to render a subsection of the full view into the entire framebuffer in the perspective camera
Many miscellaneous cleanups, bug fixes, and improvements
- The depthbuffer is now correctly populated by in the “scivis” renderer
- Updated default renderer to be “ao1” in ospModelViewer
- Trianglemesh postIntersect shading is now 64-bit safe
- Texture2D has been reworked, with many improvements and bug fixes
- Fixed bug where MPI device would freeze while rendering frames with Intel TBB
- Updates to CMake with better error messages when Intel TBB is missing

Changes in v0.9.0:

The OSPRay v0.9.0 release adds significant new features as well as API changes.

Experimental support for data-distributed MPI-parallel volume rendering
New SciVis-focused renderer (“raytracer” or “scivis”) combining functionality of “obj” and “ao” renderers
- Ambient occlusion is quite flexible: dynamic number of samples, maximum ray distance, and weight
Updated Embree version to v2.7.1 with native support for Intel AVX-512 for triangle mesh surface rendering on the Intel Xeon Phi processor (codename Knights Landing)
OSPRay now uses C++11 features, requiring up to date compiler and standard library versions (GCC v4.8.0)
Optimization of volume sampling resulting in volume rendering speedups of up to 1.5×
Updates to path tracer
- Reworked material system
- Added texture transformations and colored transparency in OBJ material
- Support for alpha and depth components of framebuffer
Added thinlens camera, i.e., support for depth of field
Tasking system has been updated to use Intel Threading Building Blocks (Intel TBB)
The ospGet*() API calls have been deprecated and will be removed in a subsequent release

Changes in v0.8.3:

Enhancements and optimizations to path tracer
- Soft shadows (light sources: sphere, cone, extended spot, quad)
- Transparent shadows
- Normal mapping (OBJ material)
Volume rendering enhancements
- Expanded material support
- Support for multiple lights
- Support for double precision volumes
- Added ospSampleVolume() API call to support limited probing of volume values
New features to support compositing externally rendered content with OSPRay-rendered content
- Renderers support early ray termination through a maximum depth parameter
- New OpenGL utility module to convert between OSPRay and OpenGL depth values
Added panoramic and orthographic camera types
Proper CMake-based installation of OSPRay and CMake find_package() support for use in external projects
Experimental Windows support
Deprecated ospNewTriangleMesh(); use ospNewGeometry("triangles") instead
Bug fixes and cleanups throughout the codebase

Changes in v0.8.2:

Initial support for Intel AVX-512 and the Intel Xeon Phi processor (codename Knights Landing)
Performance improvements to the volume renderer
Incorporated implicit slices and isosurfaces of volumes as core geometry types
Added support for multiple disjoint volumes to the volume renderer
Improved performance of ospSetRegion(), reducing volume load times
Improved large data handling for the shared_structured_volume and block_bricked_volume volume types
Added support for DDS horizon data to the seismic module
Initial support in the Qt viewer for volume rendering
Updated to ISPC 1.8.2
Various bug fixes, cleanups and documentation updates throughout the codebase

Changes in v0.8.1:

The volume renderer and volume viewer can now be run MPI parallel (data replicated) using the --osp:mpi command line option
Improved performance of volume grid accelerator generation, reducing load times for large volumes
The volume renderer and volume viewer now properly handle multiple isosurfaces
Added small example tutorial demonstrating how to use OSPRay
Several fixes to support older versions of GCC
Bug fixes to ospSetRegion() implementation for arbitrarily shaped regions and setting large volumes in a single call
Bug fix for geometries with invalid bounds; fixes streamline and sphere rendering in some scenes
Fixed bug in depth buffer generation

Changes in v0.8.0:

Incorporated early version of a new Qt-based viewer to eventually unify (and replace) the existing simpler GLUT-based viewers
Added new path tracing renderer (ospray/render/pathtracer),
roughly based on the Embree sample path tracer
Added new features to the volume renderer
- Gradient shading (lighting)
- Implicit isosurfacing
- Progressive refinement
- Support for regular grids, specified with the gridOrigin and gridSpacing parameters
- New shared_structured_volume volume type that allows voxel data to be provided by applications through a shared data buffer
- New API call to set (sub-)regions of volume data (ospSetRegion())
Added a subsampling-mode, enabled with a negative spp parameter; the first frame after scene changes is rendered with reduced resolution, increasing interactivity
Added multi-target ISA support: OSPRay will now select the appropriate ISA at runtime
Added support for the Stanford SEP file format to the seismic module
Added --osp:numthreads <n> command line option to restrict the number of threads OSPRay creates
Various bug fixes, cleanups and documentation updates throughout the codebase

Changes in v0.7.2:

Build fixes for older versions of GCC and Clang
Fixed time series support in ospVolumeViewer
Corrected memory management for shared data buffers
Updated to ISPC 1.8.1
Resolved issue in XML parser