Visual Parameter Exploration in GPU Shader Space Peter Mindek 1, Stefan Bruckner 2,1, Peter Rautek 3, and M. Eduard Gröller 1 1 Institute of Computer Graphics and Algorithms Vienna University of Technology 2 Department of Informatics University of Bergen 3 Geometric Modeling and Scientific Visualization Center King Abdullah University of Science and Technology

Motivation GPU shaders implementing visualization algorithms are complex Effects of shader variables and their combinations are examined by trial and error Peter Mindek 2

Visual Shader-Space Exploration A novel method for analysis and exploration of visualization algorithms.

Overview 4 Peter Mindek

Approach 5 Peter Mindek

Feature Vectors Peter Mindek 6

Parameter Space Visualization Peter Mindek 7

Use Case

Dual-modality medical scan MRI CT Data Peter Mindek 9

Hard Tissues MRI CT Data Peter Mindek 10

Soft Tissues MRI CT Data Peter Mindek 11

MRI CT Data Peter Mindek 12 Co-registered CT and MRI scan of a human head

Data Attributes Peter Mindek 13

Data Attributes Peter Mindek 14 Data AttributeShader Variable CT scalar valuevoxCT MRI scalar valuevoxMRI CT gradient magnitudegmCT MRI gradient magnitudegmMRI abs(voxCT – voxMRI)voxDiff abs(gmCT – gmMRI)gmDiff max(voxCT, voxMRI)voxMax max(gmCT, gmMRI)gmMax

Goal Identifying which data attributes can be used to differentiate the brain from other tissues. Peter Mindek 15

Results voxMRI Peter Mindek 16

Results voxMRI Peter Mindek 17

Results voxMRI Peter Mindek 18

Results voxMRI Peter Mindek 19

Results voxMRI gmMRI Peter Mindek 20

Results voxCTvoxDiff voxMRIvoxMax gmCTgmDiff gmMRIgmMax Peter Mindek 21

Results voxMax gmDiff Peter Mindek 22

Results voxDiff gmMRI Peter Mindek 23

Results voxDiff gmMax Peter Mindek 24

Summary A novel method for analysis and exploration of visualization algorithms Examining effects of shader variables on the resulting images Real-time, calculations executed on the GPU Peter Mindek 26

Thank you for your attention!

Membership Function Peter Mindek 28 variable A variable B

Parameter Exploration Language //. accumulation0 WAVG //. name Scalar Value float vox = dataRead(p); //. name Gradient Magnitude float gm = length(gradient); //. vector vox; gm; (1.0 - accumA) * vox voxMRI *= 1.0 /*. + confidence0 */; accumC += (1.0 - accumA) * color.rgb * vox; accumA += (1.0 - accumA) * vox; Peter Mindek 29