Sketch-based Modelling and Conceptual …“Sketch-Based Modeling and Visualization of Geological Deposition ”, Computers & Geosciences, 2014. - [C] Mattia Natali, Julius Parulek,

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

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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

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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

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Target Domain

[John Koonz]

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● 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]

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● 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

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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]

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Conformal Map Texturing

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Results – Paper A

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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

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● … 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

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Fluvial Systems

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[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

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Fault Cases

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Fault Structure

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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.