Friday 19 September 2014
Sketch-based Modelling and Conceptual Visualization of
Geomorphological Processes for Interactive Scientific Communication
Mattia Natali
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Introduction
● Ph.D. studies as part of GeoIllustrator project● Since 1st February 2011● Visualization group (UiB)
Mattia Natali
Papers:
- [A] Mattia Natali, Ivan Viola, Daniel Patel. “Rapid Visualization of Geological Concepts”, proceedings of SIBGRAPI 2012.
- [B] Mattia Natali, Tore Grane Klausen, Daniel Patel. “Sketch-Based Modeling and Visualization of Geological Deposition”, Computers & Geosciences, 2014.
- [C] Mattia Natali, Julius Parulek, Daniel Patel. “Rapid Modelling ofInteractive Geological Illustrations with Faults and Compaction”. In pro-ceedings of Spring Conference on Computer Graphics (SCCG), 2014.
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Objective
● "GeoIllustrator: Methods and tools for illustrative visualization of earth models"
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Problem Statement
● Importance of communicating abstract ideas ('visual thinking')
● Express and explain processes involved in the subsurface● Simple and quick approach● No data (create illustration from scratch)● Free-form drawing, without geometric constrains● Intuitive for non-experts (geologists who are not illustrator)
Mattia Natali
[A.Negro]
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Geologic Illustration
G. Thompson and J. Turk [1]
Haakon Fossen [2]
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Related Work
● Mostly top surface / terrain modelling● Surface interpolation if existing data● Triangulations, heightmaps, volumes
[Hnaidi et al. 2010]
[de Carpentier andBidarra 2009]
[Wang et al. 2011]
● Subsurface ==> complicated tools, (too) detailed models
Mattia Natali
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Data-free Modelling
● Procedural: fractal, erosion (lack of control)
● Geometric: by example, sketch-based
[Stava et al. 2008] [Brazil et al. 2010]
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Sketching Geology
?geology
architecture
Mattia Natali
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Motivation
● Need for a rapid modelling tool in geology● Sketch-based tools in their first stage● Few methods applied to geological field● Interactive illustrations for inter/cross-disciplinary
communication
Mattia Natali
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Target Domain
[John Koonz]
Mattia Natali
● Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories [Wikipedia]
● Illustrative visualization in geology:— discussions between experts— teaching purposes— industrial strategic decisions
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Geologic Processes
● Fold: deformation of an originally flat layer (usually produced by a sedimentation process), that has been bent by forces acting in the
crust of the earth
● Fault: originates when forces that act on a specific layer are so strong
that they overcome the rock’s elasticity and yield a fracture
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2D Sketches
[USGS]
Mattia Natali
● Reduce quantitative details in favour of simplicity and rapidity
● Replace parameters with free-form user strokes
[James Geikie]
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Sketched Illustration
G. Thompson and J. Turk [1]
3D illustrative model
Sketch-based approach Geological illustration
Mattia Natali
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Approach – Paper A
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Pipeline - Paper A
● Sketch on cross-sectional view
● Each curve defines a horizon (extruded surface)
● Two adjacent horizons identify a layer (rock type)
● Construction of a layer-cake model
● Texturing (adapted or guided, depending on geological process)
● Context and notation additions
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● Angle preservation minimizing changes from image space to 3D surface
● Illustrative texture maintains expressiveness and meaning
Courtesy of Graham R. Thompson [1]
Mattia Natali
Conformal Map Texturing
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Results – Paper A
Mattia Natali
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Time ComparisonModel definition and
non-optimized renderingIllustrator's estimation
(using Adobe Illustrator)
~ 2 min
~ 1 min
~ 1 min
~ full day
~ 1-2 hours
~ 1 hour
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Static Illustrartion
Mattia Natali
● … of a time-dependent process
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Key-frame Animations
● Introduction of temporal variable● Animated 3D synthesized illustrations
(show animation)
Initial configuration
Final configuration
Interpolation
Mattia Natali
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Fluvial Systems
Mattia Natali
[Tore Klausen]
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Approach – Paper B
Relative – Absolute
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Video
(tutorial video)
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Results – Paper B
[Tore Klausen]
● Delta deposition example
● Customizable colour-map to convey grain size distribution
[3D mimic]
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Internal Inspection
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Faulting and Compaction
● Support for:— Stratification (deposition and erosion)— Folding processes— Fluvial systems with their depositional history— Faulting processes— Compaction of layers
Mattia Natali
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Fault Cases
Mattia Natali
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Fault Structure
Mattia Natali
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Approach – Compaction
H1 = c(h2 + h3) * h1
c: R → (0,1]
h1
h2
h3
H1
h2
h3H1 := h1 compacted
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Compaction
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No Compaction - No Fault
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Compaction without Fault
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Compaction and Fault
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Methodology
● Layer-cake model, showing internal stratigraphy● Illustrative visualization of structural geology● Novel compact representation● Rendering algorithm (from our representation to volume
visualization)● Animation of 3D synthesized models
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Domain Application● Support for:
— Stratification (deposition and erosion)— Folding processes— Faulting processes (normal, reverse, blind, non-planar)— Conformal map texturing of deformed rock layers— Texture shape modification, according to user guidance— Fluvial systems with their depositional history— Compaction of layers
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● Layer-cake visualization, showing internal stratigraphy● Combine 3D sketching tools and geology● Illustrative visualizations of structural geology● Fast and intuitive modelling approach● Discontinuities given by faults
Conclusions
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Thank you for your attention!
References: - [1] G. Thompson and J. Turk, Introduction to physical geology, ser. Saunders Golden Sunburst Series. Saunders College Pub., 1998. - [2] H. Fossen, Geologi. Stein, mineraler, fossiler og olje. Fagbokforlaget, 2008.