This document discusses techniques for generating textures for expressive rock drawings in maps. It presents a programmable approach using a "recipe" to combine patterns through operators to design complex textures. This approach allows for fine control over the rendering style. It also discusses using control fields to generate spatially-varying textures with varying density and orientation based on terrain features. The techniques are applied to generate hatching arrangements and stylized curves for rendering rocky mountain areas while enhancing relief perception.

1. Texture generation for expressive rock drawing
Sidonie Christophe, Hugo Loi, Mathieu Brédif, François Lecordix, Thomas Hurtut, Romain Vergne and Joëlle Thollot
Univ. Paris-Est, LASTIG, IGN, ENSG, F-94160 Saint-Mande, France
Univ. Grenoble Alpes, CNRS, Inria, France
Polytechnique Montréal, Canada

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IGN

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IGN➔ How to design such complex textures?
➔ How to finely control the rendering style?

4. • Generic approach
• Specific approach for rocky mountain
Approach to design 2D arrangements (Loi et al. 2017)
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5. • Texture specification and design:
A ‘recipe’: combination of patterns, via operators
Programmable approach (Loi et al. 2017)
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6. • Generation of complex patterns
Programmable approach (Loi et al. 2017)
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7. • Generation of complex patterns
Programmable approach (Loi et al. 2017)
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8. • Generation of complex patterns
Programmable approach (Loi et al. 2017)
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(Loi et al. 2017)

10. • How to move from an abstract texture to a textured
area in a map?
▫ To identify rules and constraints in made-by-hand maps
▫ To develop a suitable transfer function between input parameters and
the output image.
And for the mountain?
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11. • 2 types of hatches
• one-dimensional terrain features
(ridges and valleys)
• surface information through global properties: density,
orientation and randomness.
=> Spatially-varying textures: density and orientation
=> Control fields and related control mappers
Constraints
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Input data used for rendering rocky areas

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(Loi 2015)

14. Proposition: hatching arrangements
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1 filling layer + 1 ‘ink accumulation effect’ layer Initial hand-drawn hatching
(Loi 2015) IGN
➔ Variation of heights, separation of mountain faces, multi-faces

15. Stylization step: a set of curves to be stylized
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(Christophe et al. 2016)

16. Stylization step
➔ Enhancing relief perception without seeing textures 16

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(Loi 2015, Loi et al. 2017)
Random or regular distributions for map design
➔ A set of curves: a vector layer in a cartographic pipeline

18. • Programmable approach:
-> Specification of the targeted style
-> Control over the hatching arrangement
-> Iterative design of complex structures
• Generation of cartographic data, followed by stylization step
• Relief perception: heights, edges, passes, multi-faces
Conclusion
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19. Perspectives
How to control the perception of the rendering style?
• Geometries generation and stylization
-> Shared influence on the quality of the distribution.
-> Iterative steps to adapt 2D arrangements.
• User control on the generation and stylization
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Talk Expressive Map Design: THU 6, 11:30-11:50 (Coolidge)

20. Thank you for your attention!
http://mapstyle.ign.fr
sidonie.christophe@ign.fr
Thanks to the French National Research Agency (ANR)
MapStyle project [ANR-12-CORD-0025]
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Talk Expressive Map Design: THU 6, 11:30-11:50 (Coolidge)

21. References
Christophe, S., Duménieu, B., Turbet, J., Hoarau, C., Mellado, N., Ory, J., Loi, H., Masse, A., Arbelot, B., Vergne, R.,
Brédif, M., Hurtut, T., Thollot, J., Vanderhaeghe, D. (2016). Map Style Formalization: Rendering Techniques
Extension for Cartography, Pierre Bénard; Holger Winnemöller. Expressive 2016 The Joint Symposium on
Computational Aesthetics and Sketch-Based Interfaces and Modeling and Non-Photorealistic Animation and
Rendering, May 2016, Lisbonne, Portugal. The Eurographics Association, Non-Photorealistic Animation and
Rendering.
Loi, H., Hurtut, T., Vergne, R., Thollot, J. (2017). Programmable 2D Arrangements for Element Texture Design. ACM
Transactions on Graphics Volume 36 Issue 3, June 2017. Article No. 27 DOI: 10.1145/2983617
Loi, H. Programmable Synthesis of Element Textures and Application to Cartography. (2015). PhD in Computer
Graphics. Université de Grenoble, 2015. English.
Loi, H., Hurtut T., Vergne R., Thollot J. (2013) Discrete Texture Design Using a Programmable Approach, SIGGRAPH
Talks, 2013.
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