Improving perception of intersecting 2D scalar fields. Mark Robinson Advisor: Dr. Kay Robbins

Transcription

1 Improving perception of intersecting 2D scalar fields Mark Robinson Advisor: Dr. Kay Robbins

2 Outline of Presentation 1. Definition 2. 2D, 3D visualization techniques 3. Description of stratification 4. Implementation 5. Initial experimentation 6. Demonstration 7. Conclusion and future work

3 2D Scalar Field Scalar values sampled across a 2D domain (field) Examples (neurological, topographical, superficial sensor data)

4 2D Visualization Simple to generate Simple for basic comprehension Scalar magnitude relies upon additional techniques (color maps, textures, contour lines, scale, glyphs) (single field)

5 More complex to generate Simple comprehension Occlusion and perspective deformation Scalar magnitude built into the visualization 3D Visualization (single field)

6 Multiple 2D Scalar Fields Multiple data sets sampled across a shared 2D domain Goal: Perceive individual field structure Goal: Perceive scalar relationships between fields Separate visualizations impair comprehension

7 Not as simple to generate Not as simple to comprehend 2D Visualization (multiple fields) Scalar magnitude relies upon additional techniques May not prevent occlusion

8 Examples of 2D visualizations of multiple 2D scalar fields

9 3D Visualization (multiple fields) Complex to generate Other techniques needed to differentiate individual surfaces Occlusion from self and other surfaces (reliance upon other techniques) Scalar magnitude built-in

10 Example of 3D visualization of multiple 2D scalar fields

11 2D + 3D Visualization

12 Figure 4. Comparison of a) transparent surface to b) opacity-modulating surface for molecular application. variable (in this case, simply position in x) evaluated at the solvent-accessible surface. Color represents a Figure 5. Comparison of a) transparent and b) textured statistical surface. Ozone concentrations over the Eastern seaboard of mapped to height and color in both images. 3D Techniques

13 3D Techniques

14 subject 1, trial 1, cluster 1 Overlapping Surfaces

15 Motivation Our research involves understanding relationships between intersecting 2D scalar fields 3D previous work concentrates on overlapping, but not intersecting surfaces Rendering attributes for a surface may be optimized for foreground or background, but not both

16 Motivation, contd. Traditional approaches can become perceptually confusing beyond 2 surfaces (patterns, luminance, occlusion)

17 Stratification Separate each surface into pieces above and below other surfaces Define above and below Rendering attributes for each surface piece (surface stratum) n surfaces create n! stratifications Can reduce to n2 strata (pattern/hue for order)

18 2 Surface Stratification

19 3 Surface Stratification

20 Implementation Domain-aligned surfaces = divide and conquer Break each surface into triangular primitives Triangle is basic 3D drawing primitive Developed with Java 1.4.2, JOGL, OpenGL

21 The Algorithm 1. Divide each surface into triangular primitives

22 Triangulation of Surfaces

23 Triangulation of Surfaces

24 The Algorithm, contd. 2. Place each set of aligned triangles into a separate cell 3. Sort each cell based on sort of scalar minimum

25 Detail of a Single Cell

26 The Algorithm, contd. 4. Perform initial stratification in each cell 5. Decompose triangles in each cell 6. Re-stratify the decomposed triangles in each cell

27 Decomposition and Stratification

28 The Algorithm, contd. 7. Transform and insert all triangles into a sorting array 8. Depth sort all triangles 9. Render each triangle backto-front using pre-assigned rendering attributes

29 Algorithm Comments Decomposition and stratification only needed when surfaces data changes (frame) Assumes a set of rendering attributes for each surface stratum Reduces triangle-triangle intersection errors Suited to a parallel approach

30 Experiment 1 3 surfaces: sine, cosine, and a parabolic equation 5 rendering attributes: texture pattern, texture stroke, hue, luminance, and opacity Texture stroke width and opacity are only varying attributes for strata

31 Strata 1 (bottom) Strata 2 (middle) Strata 3 (top) Cosine Texture: Grid Texture: Grid Texture: Grid Stroke: Thick Stroke: Thin Stroke: Thinner Hue: Green Hue: Green Hue: Green Luminance: High Luminance: High Luminance: High Opacity: High Opacity: Medium Opacity: Low Sine Texture: Circles Texture: Circles Texture: Circles Stroke: Thick Stroke: Thin Stroke: Thinner Hue: Red Hue: Red Hue: Red Luminance: Medium Luminance: Medium Luminance: Medium Opacity: High Opacity: Medium Opacity: Low Parabolic Texture: Diamonds Texture: Diamonds Texture: Diamonds Stroke: Thick Stroke: Thin Stroke: Thinner Hue: Blue Hue: Blue Hue: Blue Luminance: Low Luminance: Low Luminance: Low Opacity: High Opacity: Medium Opacity: Low Exp. 1 Rendering Attribute Assignment

32 Figure 6. The three test surfaces with texture stroke thickness as the only rendering attribute to vary per stratum. Figure 6. The three test surfaces with texture stroke thickness as the only rendering attribute to vary per stratum.

33 Experiment 2 Same 3 surfaces: sine, cosine, and a parabolic equation Varying texture stroke width, luminance, and opacity for strata

34 Strata 1 (bottom) Strata 2 (middle) Strata 3 (top) Cosine Texture: Grid Texture: Grid Texture: Grid Stroke: Thick Stroke: Thin Stroke: Thinner Hue: Green Hue: Green Hue: Green Luminance: Low Luminance: High Luminance: Low Opacity: High Opacity: Low Gel Opacity: Low Sine Texture: Circles Texture: Circles Texture: Circles Stroke: Thick Stroke: Thin Stroke: Thinner Hue: Red Hue: Red Hue: Red Luminance: Low Luminance: High Luminance: Low Opacity: High Opacity: Low Gel Opacity: Low Parabolic Texture: Diamonds Texture: Diamonds Texture: Diamonds Stroke: Thick Stroke: Thin Stroke: Thinner Hue: Blue Hue: Blue Hue: Blue Luminance: Low Luminance: High Luminance: Low Opacity: High Opacity: Low Gel Opacity: Low Exp. 2 Rendering Attribute Assignment

35 Figure 10. The three test surfaces with texture stroke thickness, luminance, and gel effect determined by the stratum value. Figure 10. The three test surfaces with texture stroke thickness, luminance, and gel effect determined by the stratum value.

36 Demonstration

37 Conclusions 3D visualizations are useful for perceiving shape and spatial relationships Rendering attributes can be tuned to improve perception Inter-surface occlusion and intersections inhibit perception Too early to tell...

38 Current and Future Work Formal user study Analysis of experimental results Procedural generation of textures Testing and more testing

39 User Study Invitation Comparing many permutations of rendering attributes Analyze user preferences of permutations All are welcome. Please inquire with Dr. Kay Robbins

40 Acknowledgments This work was partially supported by NIH (G12 RR13646), NSF (ACI ; EIA ) and ONR (N ). Many thanks to Dr. Kay Robbins for her insight, patience, and encouragement.