**The Narumi Renderer**  The Narumi renderer is an offline physically based renderer for research and self-education purpose. Narumi was created almost completely from scratch (except for the building blocks of asset loading). Currently it covers a relatively basic set of features. However, once the foundation has been laid, I should be ready to implement a lot of more advanced techniques. Integration with the recent real-time raytracing technologies is also on the roadmap. Current Feature Set ===============================================================================

• Bounding volume hierarchy (BVH): Hierarchical Linear BVH and binned-SAH BVH.
• Quasi Monte Carlo samplers.
• Direct lighting integrator.
• Incremental path tracing integrator with Russian roulette.
• Bidirectional path tracing integrator (with multiple importance sampling).
• Volumetric path tracing integrator.
• Area lights (polygonal mesh) and punctual lights.
• Image-based lighting.
• Basic matte, mirror (specular reflection) and glass (specular transmission) material.
• Microfacet-based material (GGX), both reflection and transmission. Importance sampling based on visible NDF function.
• Unified material model based on the Disney 2015 BSDF.
• Texturing with ray differential anti-aliasing; Bump mapping.
• Homogeneous participant media with common phase functions (isotropic / Henyey-Greenstein).
• Subsurface scattering support based on photon beam diffusion.
• Object instancing.
• CPU parallelization via multithreading.
• Custom scene representation to define everything including integrator, camera, geometry, lighting, and material. Conversion between source asset and custom representation is provided.

Notes ===============================================================================

• [Notes on the implementation of the unified material model.](blog-unified-material.html)
• [Subsurface scattering implementation in Narumi.](blog-sss.html)

Future Roadmap ===============================================================================

• More advanced integrators such as VCM and MLT (Multiplexed MLT).
• More advanced material such as:
  • Specular microstructure, such as Yan, Ling-Qi, et al. "Position-normal distributions for efficient rendering of specular microstructure."
  • Multiple-scattering material, such as Heitz, Eric, et al. "Multiple-scattering microfacet BSDFs with the Smith model."
  • Layered material, such as Belcour Laurent, "Efficient Rendering of Layered Materials using an Atomic Decomposition with Statistical Operators".
• More (heterogeneous) participant media. Possibly OpenVDB integration.
• More subsurface scattering, such as pathtraced subsurface scattering, and Frisvad, Jeppe Revall, Toshiya Hachisuka, and Thomas Kim Kjeldsen. "Directional dipole model for subsurface scattering."
• Sorted raytracing / deferred shading.
• Subdivision and displacement map.
• Adaptive sampling.
• Monte Carlo denoising, such as Schied, Christoph, et al. "Spatiotemporal variance-guided filtering: real-time reconstruction for path-traced global illumination."
• Real-time ray-tracing (Direct 12 DXR / Nvidia RTX).

Gallery =============================================================================== Above and below are some images rendered by Narumi demonstrating different features. Hopefully the gallery will keep growing ;) Asset sources:

• Testing "knob" modified from .
• Textures from FreePBR ().
• HDR Environment maps from .
• Cornell box, bunny, sculpture head modified from McGuire Computer Graphics Archive ().
• Exotic car purchased from Turbosquid.

)](images/gallery/serapis-sss/pngs/serapis-sss-50.png)