APPLYING PARALLEL PROCESSING APPROACH

FOR INTERACTIVE GLOBAL ILLUMINATION

By 

Mahmoud Moustafa ZidanBasic Sciences Department

Faculty of Computer and Information SciencesAin Shams University

 Under Supervision of

 Prof. Dr. Taymoor Nazmy

Computer Science DepartmentFaculty of Computer and Information Sciences

Ain Shams University 

Prof. Dr. Mohamed HashemInformation Systems Department

Faculty of Computer and Information SciencesAin Shams University

 Dr. Haytham El-Messiry

Computer Science DepartmentFaculty of Computer and Information Sciences

Ain Shams University

AGENDA Introduction to RT, GI, GPU Previous Work (GI, Hierarchy

Construction) Proposed Approach for Hierarchal Tree

Construction Proposed Algorithm for Building Binned

SAH BVH Proposed Approach for Parallel Ray

Tracing and Photon Mapping Results Conclusion

RAY TRACING , GLOBAL ILLUMINATION

GPU ARCHITECTURE, GPGPU, CUDA

PREVIOUS WORK -RENDERING- Offline VS Interactive (Real-time)

RenderingRasterizationPhysically Based Rendering Reyes RenderingPrecomputed Radiance Transfer

Parallel Hieratical Tree Construction KD-Tree [Zhou et al. 2008]SAH BVH, LBVH [Lauterbach et al. 2009]

Interactive (Real-time) GPU RT , GPU PMReal-time RT [Zhou et al. 2008] Interactive PM [Wang et al. 2009]

PROPOSED APPROACH FOR HIERARCHAL TREE CONSTRUCTION Data parallel utilities

Data Parallel Primitive Algorithms (main building blocks for parallel algorithms)

Data parallel operator Data parallel code fragment

Parallel extensions to math/logic operators on GPU

A simple reformulation of previous parallel algorithms

on GPU

PROPOSED ALGORITHM FOR BUILDING BINNED SAH BVH Pervious work

GPU SAH BVH [Lauterbach et al. 2009] (high quality tree, slow construction)

GPU LBVH [Lauterbach et al. 2009] (moderate (low) quality tree, fast construction)

HLBVH

PROPOSED APPROACH -BINNED SAH BVH- Evaluates SAH as (small) (variable)

number of candidates (e.g. 32-4) is enough for good tree [instead of (large) (fixed) candidates in SAH BVH]

Divide triangles into fixed size chunks for better work load

Evaluates SAH at chunks and used parallel scans to share intermediate values of SAH (work efficiency)

Also use LBVH to build higher tree levels for faster algorithms

PROPOSED APPROACH FOR RT, PM Entire mapping of all rendering stages

on GPU A simple reformulation of previous

approaches for both ray tracing and photon mapping

Evaluate proposed hierarchy for binned SAH BVH

PARALLEL GI ON GPU

RESULTS Ray tracing evaluation

RESULTS Witted ray tracing

RESULTS Photon mapping

DEMO

CONCLUSION New approach for GPU parallel code

which simplifies previous proposed algorithms

Proposed fast algorithm for building BVH

FUTURE WORK New parallel template library (e.g.

thrust) Use the LBVH appraoch for fast point-

based KD-tree Enhance ray tracer for distributed

effects Enhance photon mapping for area light

ACKNOWLEDGEMENT

QUESTIONS