ParaView 6.1 with OSPRay GPU Pathtracing on Intel Arc Pro B70

Reproducible build instructions for ParaView 6.1.0 with hardware ray‑tracing / pathtracing on Intel Arc Pro B70 (Big Battlemage, BMG‑G31, 32 GB ECC GDDR6) on Ubuntu 26.04 LTS with oneAPI 2026.0.

The official Kitware ParaView 6.1.0 binary release ships only CPU‑only OSPRay 2.7.1. This repo documents how to replace it with **OSPRay 3.2.0

• the GPU module (libospray_module_gpu.so.3.2.0)** built against Intel's SYCL/Level‑Zero stack, so that the OSPRay path tracer in ParaView actually runs on the GPU instead of the CPU.

Tested on:

Component	Version
GPU	Intel Arc Pro B70 (BMG‑G31), 32 GB ECC GDDR6
CPU	Intel Core Ultra 9 285K (Arrow Lake‑S)
OS	Ubuntu 26.04 LTS (Resolute), kernel 7.0
Intel oneAPI	2026.0 (DPC++/icx/icpx)
Level Zero	1.28 + libze-intel-gpu-raytracing 1.2.3
compute‑runtime	26.05
OSPRay	3.2.0 with BUILD_GPU_SUPPORT=ON
Embree	4.3.3 (with patch, see below)
OpenVKL	2.0.1 (with patch)
OpenImageDenoise	2.4.0 (JIT only on Battlemage)
ParaView	6.1.0
CMake	4.2.x

---

TL;DR

git clone https://github.com/heikogleu-dev/Paraview---Intel-B70-Pro-OSPRAY-Raytracing-Pathtracing.git
cd Paraview---Intel-B70-Pro-OSPRAY-Raytracing-Pathtracing
chmod +x scripts/*.sh
./scripts/00-apt-deps.sh        # ~3 min
./scripts/10-build-ospray-gpu.sh # ~30-60 min, ends with libospray_module_gpu.so
./scripts/20-build-paraview.sh   # ~60-180 min, ends with paraview executable
./scripts/30-paraview-gpu-launcher.sh /path/to/your/case.foam

---

Why this is needed

OSPRay GPU rendering is officially "beta" (per the OSPRay README) but production‑ready in practice. The bottleneck for using it on Battlemage hardware is that none of the upstream binaries ship a working stack:

• The Intel® Rendering Toolkit Superbuild's default config builds OSPRay without the GPU module (it passes BUILD_GPU_SUPPORT to OSPRay's main CMakeLists, where the actual flag is OSPRAY_MODULE_GPU — they don't translate). It also pins Embree 4.4.0, which broke the SYCL device‑side API that OSPRay 3.2.0 uses (the *FromScene functions became host‑only, replaced by *FromTraversable).
• OSPRay's own superbuild uses the right version pins (Embree 4.3.3) and the right flag, but Embree 4.3.3's source uses removed SYCL methods (sycl::sub_group::shuffle*) that were dropped in DPC++ 2026.0.
• OpenImageDenoise's default AOT compilation only targets older iGPUs, Alchemist Arc, and Ponte Vecchio data‑center GPUs — Battlemage is not on the list, and the AOT compiler segfaults if asked to do PVC on a non‑PVC system.
• CMake 4.0+ removed compatibility with cmake_minimum_required(VERSION < 3.5), which several upstream subprojects in the build chain still declare.
• glibc ≥ 2.43 declares nan(...) as a function, which collides with rkcommon's #define nan floatbits(0x7FBFFFFF) macro when rkcommon/math/math.ih is included from C++ code (which OpenVKL's GPU module does).

The four patches in patches/ fix exactly these issues. The build scripts apply them at the right point in the build process.

What works after this build

• ✅ ParaView 6.1.0 GUI launches with -DPARAVIEW_ENABLE_RAYTRACING=ON
• ✅ "OSPRay path tracer" and "OSPRay raycaster" available as render backends in the Render View properties panel under Ray Traced Rendering → Back End
• ✅ Default device is GPU (driven by OSPRAY_LOAD_MODULES=gpu + OSPRAY_DEVICE=gpu env vars set by the launcher script — the GUI itself has no CPU/GPU switch)
• ✅ SYCL device 0 (the discrete Arc Pro B70 = Intel(R) Graphics [0xe223]) is selected at runtime — confirm via:

  SYCL_UR_TRACE=1 ospTutorial --osp:load-modules=gpu --osp:device=gpu
  

• ✅ Path tracing of automotive‑scale CFD scenes (10⁷–10⁸ cells) for high‑quality video export
• ✅ OpenImageDenoise (JIT) on the GPU as well

What does NOT work / is not in this build

• ❌ ANARI plugin (Kitware doesn't ship it in source builds enabled by default; it's a separate effort and the Intel ANARI backend would itself sit on top of OSPRay anyway, so for Intel hardware the direct OSPRay path is more efficient).
• ❌ MPI / cluster rendering — set BUILD_OSPRAY_MODULE_MPI=ON and install libopenmpi-dev if you need it.
• ❌ AOT compilation of OIDN kernels for Battlemage — Intel needs to add bmg-g21,bmg-g31 to the OIDN AOT target list. Until then, JIT
  • persistent JIT cache (which we enable via the launcher script) handles the small first‑frame overhead.

Repository layout

.
├── README.md                     ← you are here
├── patches/                      ← four upstream patches, applied by the build scripts
│   ├── 01-rkcommon-math-ih-nan.patch
│   ├── 02-embree-sycl-subgroup-api.patch
│   ├── 03-oidn-disable-aot-for-non-supported-gpu.patch
│   └── 04-cmake-policy-version-minimum.patch
├── scripts/
│   ├── 00-apt-deps.sh            ← apt one‑liner for build deps (Qt6, Python3, GLFW, …)
│   ├── 10-build-ospray-gpu.sh    ← OSPRay 3.2.0 + GPU module (uses OSPRay's own superbuild)
│   ├── 20-build-paraview.sh      ← ParaView 6.1.0 from source against the new OSPRay
│   └── 30-paraview-gpu-launcher.sh ← runtime wrapper (LD_LIBRARY_PATH + ONEAPI_DEVICE_SELECTOR)
└── docs/
    ├── verification.md           ← how to confirm the GPU is actually being used
    ├── rendering-tips.md         ← OSPRay material gotchas, perf settings, known runtime quirks
    └── troubleshooting.md        ← every error we hit, with logs & fixes

Prerequisites (not installed by 00-apt-deps.sh)

• Intel oneAPI Base Toolkit 2025.3+ (we used 2026.0): provides icx / icpx (DPC++) and the SYCL runtime. Install via Intel's apt repo: https://www.intel.com/content/www/us/en/docs/oneapi/installation-guide-linux/2024-2/apt-005.html
• Intel Level Zero + GPU runtime + ray‑tracing extension:

  sudo apt install libze-dev libze-intel-gpu1 libze-intel-gpu-dev libze-intel-gpu-raytracing intel-opencl-icd
  

• A working clinfo and sycl-ls should report your B70 as e.g. [level_zero:gpu] Intel(R) Graphics [0xe223]. If they don't, the build will succeed but rendering will fall back to CPU silently.

Verification

After install, run:

SYCL_UR_TRACE=1 ONEAPI_DEVICE_SELECTOR=level_zero:0 \
  ~/opt/ospray-gpu/ospray/bin/ospTutorial \
    --osp:load-modules=gpu --osp:device=gpu 2>&1 | grep "device:"

Expected output:

SYCL_UR_TRACE:   device: Intel(R) Graphics [0xe223]

0xe223 is the PCI device ID of the BMG‑G31 silicon used in the Arc Pro B70 (and B65). If you see a different device ID, you're rendering on a different GPU than you think you are. See docs/verification.md.

License & contributions

The patches in this repo are derivative changes to upstream projects released under Apache 2.0 (rkcommon, Embree, OpenVKL, OIDN, OSPRay) — they are licensed under the same terms.

If you reproduce this build on different hardware (Arc Pro B50/B60, older Alchemist Arc, etc.) and any of the patches need adjustment, please open an issue or PR.

Acknowledgements

Built and documented while debugging the build interactively with Claude Code (Claude Opus 4.7).