Combining Single and Packet-Ray Tracing for Arbitrary Ray Distributions on the Intel MIC Architecture

Area of Science:

• Computer Graphics
• Parallel Computing
• Hardware Acceleration

Background:

• Wide Single Instruction, Multiple Data (SIMD) hardware offers power and area efficiency but struggles with incoherent ray tracing.
• Existing methods like packet tracing and per-lane traversal stacks show poor performance with diverging rays due to SIMD utilization loss or memory system strain.

Purpose of the Study:

• To develop an efficient ray tracing scheme for incoherent rays on wide SIMD hardware.
• To introduce a hybrid tracing approach that adapts to varying ray coherence.

Main Methods:

• Introduced a single-ray tracing scheme utilizing one traversal stack on 16-wide SIMD hardware.
• Employed a bounding-volume hierarchy with a branching factor of four for acceleration.
• Developed a hybrid scheme that transitions from packet tracing to single-ray tracing based on ray divergence.

Main Results:

• The proposed single-ray scheme efficiently handles incoherent rays on 16-wide SIMD.
• The hybrid tracing scheme consistently outperformed both packet and single-ray tracing across diverse scenes and ray distributions.
• Demonstrated superior performance on the Intel Many Integrated Core architecture.

Conclusions:

• The novel hybrid ray tracing scheme offers a significant performance improvement for incoherent rays on wide SIMD architectures.
• Adaptive switching between packet and single-ray tracing effectively addresses varying ray coherence challenges.
• This approach provides a robust solution for efficient ray tracing in complex graphical applications.