This post presents best practices for implementing ray tracing in games and other real-time graphics applications. We present these as briefly as possible to…
Overview
This article provides best practices for implementing ray tracing in real-time graphics applications, focusing on optimization techniques and performance improvements. It draws on insights from a presentation by NVIDIA engineers at the 2019 GDC, offering actionable tips for developers.
What You'll Learn
1
How to optimize acceleration structure build/update to minimize latency
2
Why denoising is essential for ray tracing effects
3
How to effectively manage memory in ray tracing applications
4
When to use asynchronous compute queues for overlapping tasks
Prerequisites & Requirements
- Understanding of ray tracing concepts and graphics programming
- Familiarity with NVIDIA RTX and Denoiser SDK(optional)
Key Questions Answered
What are the best practices for optimizing ray tracing performance?
Best practices include optimizing acceleration structure builds to take no more than 2ms, using denoising techniques, and leveraging hardware acceleration for traversal. Additionally, overlapping builds with other tasks using asynchronous compute queues can significantly enhance performance.
How does the choice of build flags affect ray tracing performance?
Choosing the right build flags, such as PREFER_FAST_TRACE or PREFER_FAST_BUILD, can significantly impact the performance of ray tracing operations. For instance, PREFER_FAST_TRACE allows for the fastest possible trace but may slow down builds, while PREFER_FAST_BUILD is ideal for dynamic geometry.
What is the impact of shading complexity on ray tracing?
Increasing shading complexity can negatively affect performance, especially during ray tracing. It is recommended to maintain simpler shaders compared to rasterization to minimize divergence and improve efficiency.
What tools are recommended for profiling ray tracing applications?
NVIDIA Nsight Graphics and Nsight Systems are recommended for profiling and debugging ray tracing applications. These tools provide insights into shader performance, memory usage, and overall system profiling.
Key Statistics & Figures
Acceleration structure build/update time
at most 2ms
This is the target time for optimizing acceleration structure management.
GPU throughput for full builds
O
100 million
GPU throughput for updates
O
1 billion
Extra VRAM used by ray tracing implementations
1 to 2 GB
This additional memory is typically consumed by acceleration structure resources and ray tracing-specific buffers.
Technologies & Tools
Graphics Technology
Nvidia Rtx
Used for hardware acceleration in ray tracing applications.
Graphics Technology
Nvidia Denoiser SDK
Provides high-quality denoising for ray-traced effects.
Key Actionable Insights
1Optimize your acceleration structure management by utilizing asynchronous compute queues to hide build costs.This practice allows for smoother frame rates in real-time applications by overlapping the costs of building acceleration structures with rendering tasks.
2Implement denoising techniques using the NVIDIA RTX Denoiser SDK to improve the visual quality of ray-traced effects.Denoising is crucial for achieving high-quality images in ray tracing, especially in dynamic scenes where noise can be prevalent.
3Batch and merge your build/update calls for bottom-level acceleration structures to maximize GPU occupancy.By grouping geometries based on spatial locality, you can create more efficient data structures that enhance ray traversal performance.
Common Pitfalls
1
Failing to optimize shading complexity can lead to performance degradation in ray tracing applications.
As shading complexity increases, it can cause significant performance issues due to increased register pressure and divergent memory accesses. Keeping shaders simpler can mitigate these effects.
2
Neglecting to manage memory effectively can result in excessive VRAM usage and slow performance.
Ray tracing applications can consume additional memory, so developers should be mindful of memory management techniques to optimize resource usage.
Related Concepts
Ray Tracing Optimization Techniques
Asynchronous Compute In Graphics Programming
Denoising Methods For Real-time Graphics