Ray Tracing with CUDA

Ray tracing with GPGPUs

Pedro G. M. R. Alves and Ricardo Biloti,Unicamp & INCT-GP, BR

quarta-feira, 21 de setembro de 11

Ray Tracing


Ray Tracing

The ray theory is a high frequency approximation of the wave equation solution.

Rays are preferential paths for energy propagation.


Ray Tracing


Ray Tracing

Subsurface Model


Ray Tracing

Subsurface Model

Propagation Times


Ray Tracing

Direct Problem

Subsurface Model

Propagation Times


Ray Tracing

Direct Problem

Subsurface Model

Propagation Times

Inverse Problem


Ray Tracing


Ray Tracing

Comparison between real and simulated data.


Ray Tracing


The synthetic model may need modification.


Ray Tracing



More rays to trace.


Ray Tracing



More rays to trace.

This step should be as fast as possible.


Ray Tracing


We need to solve a differential equation system to calculate a ray's path.

Ray Tracing

8<

:

@X@t = v2P

@P@t = 1

vrv

1


Ray Tracing


Runge-Kutta method to solve each equation.

Ray Tracing



Interpolation method to find velocity on the ray's path.

Ray Tracing



Interpolation method to find velocity on the ray's path.

Should be done fast.

Ray Tracing


Sequential Processing VS

Parallel Processing



Parallel Processing

In the Past: Increasing a computer's performance -> Increasing CPU's operating frequency.



Parallel Processing

In the Past: Increasing a computer's performance -> Increasing CPU's operating frequency.

Today: Multi-Core processors.



Parallel Processing


GPUs (Graphic Processor Unit).


Parallel Processing



Dedicated processor to the graphic card.


Parallel Processing




Solution for graphic processing.


Parallel Processing




Solution for graphic processing.

Graphic applications use a lot of parallel processing, so GPUs have to be good in it.


Parallel Processing



Parallel Processing


Cores

Price

CPU

10

High


Parallel Processing


Cores

Price

CPU GPU

10 +400

High Popular


Parallel Processing


CUDA


CUDA

Developed by NVIDIA.


CUDA


Programs being executed on GPU.


CUDA


Programs being executed on GPU.

GPU being used as a General Purpose processor (GPGPU), taking advantage of parallel processing capability.


CUDA


A thread is a portion of a program that runs independently of and concurrently with other portions of the program.

CUDA


A thread is a portion of a program that runs independently of and concurrently with other portions of the program.

Thousands of threads running simultaneously on GPU against a few ones on CPU.

CUDA


Ray tracer


Ray tracer

Ray Tracer application developed in C with support to CUDA.


Ray tracer


Excellent for CUDA implementation.


Ray tracer


Excellent for CUDA implementation.

Simultaneous path calculation for several rays.


Ray tracer


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Ray tracer

Marmousi Modelquarta-feira, 21 de setembro de 11

Ray tracer


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Ray tracer


Ray tracer


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Ray tracer


Ray tracer


Ray tracer 0

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Ray tracer


Tracer supports parallel processing with CUDA (GPU) and sequential/parallel processing with the CPU.

Ray tracer



Processing performance by CPU uses GSL library.

Ray tracer



Processing performance by CPU uses GSL library.

CUDA doesn't support most of the common C libraries.

Ray tracer


Benchmark


Benchmark application.

Benchmark



GPU with CUDA.

CPU performing sequential processing.

CPU performing parallel processing.

Benchmark



GPU with CUDA.

CPU performing sequential processing.

CPU performing parallel processing.

Least-squares method to analyse data.

Benchmark


Benchmark


Benchmark

CPU: Intel Xeon X5570 @ 2.93GHz, 4 cores | GPU: NVIDIA Tesla C1060 @ 1.3 GHz, 240 cores

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Processing time (s)

Rays

GPU with CUDACPU parallel

CPU sequential


Benchmark


Benchmark

CPU: Intel Xeon X5570 @ 2.93GHz, 4 cores | GPU: NVIDIA Tesla C1060 @ 1.3 GHz, 240 cores

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Rays

GPU with CUDACPU parallel

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Benchmark


66%

Benchmark

against parallel processing performed by CPU.


Benchmark


82%

Benchmark

against sequential processing performed by CPU.


Benchmark


Benchmark

Processing Type / Processor Parallel/CPU Sequential/CPU

Parallel/GPU 66% 82%

GPU's performance increase against CPU


Conclusion


Acknowledgements

GêBR project

Petrobras

WIT Consortium


Ray Tracing with CUDA

Documents

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