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Custom shaders for volume rendering and data processing on GPU

Key Investigators

• Kyle Sunderland (Queen’s University, Canada)
• Steve Pieper (Isomics)
• Andras Lasso (Queen’s University, Canada)

Project Description

Objective

• Make custom GLSL shaders available in Slicer for:
  • custom volume rendering effects
  • GPU-accelerated image processing

Approach and Plan

• Improve recently added GLSL uniforms class
• Add GLSL code and variables to MRML nodes and displayable managers (use case: depth-encoded rendering)
• Make GPU-based filters work that have been developed for fractional labelmap processing
• Investigate existing implementation of GLSL shaders for image processing (vtkOpenGLFilters, vtkOpenGLTexture)

Progress and Next Steps

• Progress made at last project week

• Get methods for uniforms

• Discussed options for implementing and decided that it would be best to utilize and modify the classes in VTK
• Existing implementation can render from vtkImageData back to vtkImageData

• Need to implement a class that be used for multi-pass image processing algorithms to be run through GLSL shaders, without returning the intermediate result to memory

• Next steps:
  • Fork SlicerVTK and develop VTK based classes for GLSL image processing algorithms (see vtkOpenGLImageAlgorithmHelper)
  • Support for multipass algorithms wihtout writing back to memory

Result

• To be completed

Illustrations

Philips 3D US	Chroma-depth in PRISM	Depth peeling in PRISM

Background and References

• Work at the previous Project Week