Category: production

Intel Open Image Denoise is an open source library of high-performance, high-quality denoising filters for images rendered with ray tracing. Intel Open Image Denoise is part of the Intel® oneAPI Rendering Toolkit and is released under the permissive Apache 2.0 license.

The purpose of Intel Open Image Denoise is to provide an open, high-quality, efficient, and easy-to-use denoising library that allows one to significantly reduce rendering times in ray tracing based rendering applications. It filters out the Monte Carlo noise inherent to stochastic ray tracing methods like path tracing, reducing the amount of necessary samples per pixel by even multiple orders of magnitude (depending on the desired closeness to the ground truth). A simple but flexible C/C++ API ensures that the library can be easily integrated into most existing or new rendering solutions.

At the heart of the Intel Open Image Denoise library is a collection of efficient deep learning based denoising filters, which were trained to handle a wide range of samples per pixel (spp), from 1 spp to almost fully converged. Thus it is suitable for both preview and final-frame rendering. The filters can denoise images either using only the noisy color (beauty) buffer, or, to preserve as much detail as possible, can optionally utilize auxiliary feature buffers as well (e.g. albedo, normal). Such buffers are supported by most renderers as arbitrary output variables (AOVs) or can be usually implemented with little effort.

https://github.com/OpenImageDenoise/oidn

https://shangchenzhou.com/projects/ProPainter/

https://github.com/sczhou/ProPainter

https://en.wikipedia.org/wiki/Bounding_volume_hierarchy#:~:text=BVHs%20are%20often%20used%20in,intersected%20by%20the%20current%20ray.

Bounding volume hierarchies are used to support several operations on sets of geometric objects efficiently, such as in collision detection and ray tracing. A bounding volume hierarchy (BVH) is a tree structure on a set of geometric objects. All geometric objects, which form the leaf nodes of the tree, are wrapped in bounding volumes.

BVHs are often used in ray tracing to eliminate potential intersection candidates within a scene by omitting geometric objects located in bounding volumes which are not intersected by the current ray. BVH is a crucial component in ray tracing rendering engines like Arnold, as it helps accelerate ray intersection tests and reduce resource costs.

Users do not have control over RAM consumption of the BVH. Here are some tips to optimize Arnold renders when BVH is the bottleneck:

Optimize Your Scene Geometry. Simplify or optimize your 3D models and scene geometry. Complex geometry can lead to larger BVH structures and longer BVH build times. Consider using LODs (Level of Detail) or proxy objects for distant geometry to reduce the BVH complexity.

Use Arnold Stand-ins and Proxies. Arnold Stand-ins and proxies allow you to load complex geometry only when needed, reducing the BVH complexity during the initial BVH build. This can be particularly useful for scenes with a lot of high-poly assets.

Denoising. Applying denoising to your final render can help reduce the number of rays required and consequently, the BVH intersection tests.

Render in Layers. If your scene has many elements, consider rendering it in layers. This allows you to optimize each layer individually, potentially reducing BVH build times.

Distribute Rendering. If you have access to a render farm or multiple machines, distribute the rendering workload. This can significantly reduce rendering time as each machine can handle a portion of the BVH calculations.