1. Sponsored by Depth-Aware Coherent Line Drawings Marc Spicker 1, Julian Kratt 1, Diana Arellano 2, Oliver Deussen 1 1 University of Konstanz, Germany 2 Filmakademie Baden-Württemberg, Germany

2. Sponsored by SA2015.SIGGRAPH.ORG Line drawing to depict form and structure Well suited but sometimes problematic: Information about spatial arrangement is lost! Motivation

3. Sponsored by SA2015.SIGGRAPH.ORG Line drawing to depict form and structure We propose: Improved depth perception and object differentiation! Motivation

4. Sponsored by SA2015.SIGGRAPH.ORG Related Work Image space line drawings: [Canny 1986] [Kang et al. 2007] [Winnemöller et al. 2006] [Winnemöller et al. 2012] [Rosin and Lai 2010]

5. Sponsored by SA2015.SIGGRAPH.ORG Related Work Depth information in NPR: [Deussen and Strothotte 2000] [Everts et al. 2009] [Luft et al. 2006] [Tan et al. 2005] [Saito and Takahashi 1990]

6. Sponsored by SA2015.SIGGRAPH.ORG Contributions More control over line drawings Line width: Small Details: Few Line width: Large Details: Many Focus: Weak Focus: Strong

7. Sponsored by SA2015.SIGGRAPH.ORG Our Method Input [Kang et al. 2007] Ours (Style 2) Ours (Style 1)

8. Sponsored by SA2015.SIGGRAPH.ORG Overview Input Color Adaptive Edge Tangent Flow Gaussian Smoothing Flow-based DoG Line Drawing Noise Suppression Line Parameters Smooth Radius Input Depth

9. Sponsored by SA2015.SIGGRAPH.ORG Flow-based Difference-of-Gaussians Input(1)(2)(3) Algorithm from [Kang et al. 2007]: 1.Edge tangent flow (ETF) 2.Difference-of-Gaussians 3.Gaussian weighting along flow (FDoG)

10. Sponsored by SA2015.SIGGRAPH.ORG Adaptive Edge Tangent Flow Extension to ETF construction: Average angular deviation InputOriginalOurs

11. Sponsored by SA2015.SIGGRAPH.ORG Flow-based Difference-of-Gaussians Filter response forms an area: Gradient ascend orthogonal to ETF for finding maximum response.

12. Sponsored by SA2015.SIGGRAPH.ORG Line Drawing Input Depth Distance to Maximum Line Width Noise Suppression Details

13. Sponsored by SA2015.SIGGRAPH.ORG Line Drawing Styles Line ParametersThick lines in close regions. Thin line in close regions; Thick and faded out at the back. ReasoningFocus user attention to close objects. Details in front. Analogue to painterly rendering. Line ParametersThick lines in close regions. ReasoningFocus user attention to close objects. Style 1Style 2

14. Sponsored by SA2015.SIGGRAPH.ORG Line Drawing Styles - Applications Importance map (inst. of depth) for highlighting. Focus on eyes and mouth regions with our line drawing styles.

15. Sponsored by SA2015.SIGGRAPH.ORG Line Drawing Styles - Future Work Application: Individuals with Autism Spectrum Disorder Focus on facial regions that convey emotions Abstract other details of the face

16. Sponsored by SA2015.SIGGRAPH.ORG User study ClaimOur line drawings improve depth perception. TaskOrder objects from front to back. ResultsImproved orderings (~0.88) vs. uniform lines (~0.55) Not as strong as shadows (~0.95)

17. Sponsored by SA2015.SIGGRAPH.ORG User study ClaimOur line drawings allow to set the focus. TaskMark the area in focus. ResultsAll subjects able to determine focal area with depth-of-field 76% of subjects in our line drawing

18. Sponsored by SA2015.SIGGRAPH.ORG Results Input [Kang et al. 2007] Ours (Style 2) Ours (Style 1)

19. Sponsored by SA2015.SIGGRAPH.ORG Results Input [Kang et al. 2007] Ours (Style 2) Ours (Style 1)

20. Sponsored by SA2015.SIGGRAPH.ORG Limitations ETF vector-based representation: Problems as described in [Zhang et al. 2007] Parameters (e.g. kernel size) scale dependent Coherence limited

21. Sponsored by SA2015.SIGGRAPH.ORG Conclusion Improved Edge Tangent Flow construction method Flow-based morphological filter Two line drawing styles for better depth perception and object differentiation

22. Sponsored by SA2015.SIGGRAPH.ORG Thank you! Contact : marc.spicker@uni-konstanz.de