Lecture 3D Geometry Processing
Introduction
Prof. Dr. David Bommes
Computer Graphics Group

People

David
Heng

Acknowledgements

Mario Botsch
Mark Pauly

  • Collaboration on future extensions and improvements of the course

Acknowledgements

  • Many more people contributed directly or indirectly
    • Pierre Alliez, Keenan Crane, Marcel Campen, Bruno Levy, Misha Kazhdan, Leif Kobbelt, Sylvain Levebvre, Niloy Mitra, Szymon Rusinkiewicz, Justin Solomon, …

General Information

  • Time and location
    • Lecture: Thursday, 09:15 - 11:00, Room 001, Engehaldenstr. 8
    • Exercises: Thursday 11:15 - 12:00, Room 001, Engehaldenstr. 8
    • Supervised C++ Programming (optional): TBD
  • 5 ECTS Credits
  • ILIAS
    • slides, exercises, submissions, online forum, etc.
  • Take advantage of the online forum to get advice!

Literature

  • Botsch, Kobbelt, Pauly, Alliez, Levy: Polygon Mesh Processing, AK Peters, 2010

pmp-book.org

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Quiz Setup

Quiz Example

Which of the following is true for you?
Bachelor Student
Master Student
PhD Student
University of Bern
University of Neuchâtel
University of Fribourg

A Real Quiz

Is the following statement true?

The sphere is the only 3D shape of constant width.

Yes
No there are others
No
For example the Reuleaux tetrahedron is of constant width too

Geometry - γεωμετρία

  • geo = earth

Geometry - γεωμετρία

Geometry - γεωμετρία

  • metria = measure

A little bit of History

  • Earliest recorded beginnings of geometry:
    • 3000 B.C. by Indus Valley civilization (north India) and Babylonina People
  • Practical motivation
    • surveying
    • construction
    • astronomy

Surveying Team (Wikipedia)

A little bit of History

Fragment of Euclid’s Elements
“widely considered the most influential textbook of all times”
300 B.C. (Wikipedia)

Table of Geometry from the 1728 Cyclopaedia (Wikipedia)

A little bit of History

  • Classic Geometry was based on compass-and-straightedge construction

(Wikipedia)

Construction of a square (Wikipedia)

A little bit of History

  • Our Goal: complex geometry

A little bit of History

  • Modern Geometry joins classic geometry and algebra/calculus
  • Analytic Geometry = Geometry with Coordinates and equations
  • Ability to compute!
    • $ x^2 + y^2 = r^2$

René Descartes (1596-1650) (Wikipedia)

What is Geometry?

  • “science of shape”
  • measurements
    • length
    • area
    • volume
    • angle
    • curvature
    • deformation
  • analytic and/or constructive
  • visual nature often allows for intuitive arguments!
    • typically first a picture then a formal algebraic proof

Application Domains

  • Cultural Heritage

David
1G sample points
St. Matthew
4G sample points

© Digital Michelangelo Project

Application Domains

  • Automotive Industry

Real model
Scanner point cloud
Reconstructed surface
Flow simulation

Application Domains

  • Digital Avatars

Camera-based scanner
Acquired data

© ICT

Application Domains

  • Digital Avatars

Full body scanner
Virtual Character

Application Domains

  • Surgery Simulation

Images: Virtamed

Application Domains

  • Urban Modeling

Google street view scanner
Google Earth

Application Domains

  • Digital Fabrication

Digital Fabrication

  • A revolution in materials and fabrication
    • 3D printing, laser cutting, CNC machining, robotic fabrication, etc.
    • digital & smart materials
  • An opportunity for graphics research
    • new and complex materials & geometries
    • rapid prototyping and industrial production of custom models
    • intuitive user interfaces for computational, material-aware design
    • data-driven modeling and machine learning
    • control strategies robotic fabrication and assembly
    • fully digital workflow, from design, visualization, simulation, to fabrication

Digital Fabrication

  • Additive Manufacturing

Digital Fabrication

3dprint.com

Digital Fabrication

Digital Fabrication

3D Content Creation Pipeline

3D Geometry Processing Course

  • Core Questions
    • What is geometry and where is it used?
    • How can we represent geometry?
    • Which structural properties do we need in practice? (raw geometry vs. practically useful)
    • What kind of basic operations can we perform to process geometry?
    • How can we go from physical to digital?
    • How can we go from digital to physical?
    • What advanced operations can be perform to manipulate geometry?
    • How can we efficiently implement geometry processing algorithms?

Course Overview

  • Introduction
  • 3D Content Creation
  • Geometry Fundamentals
  • Basic Processing Algorithms
  • Solving Laplace Equations
  • Advanced Methods

Course Overview

  • Introduction
  • 3D Content Creation
    1. Scanning & Fabrication
  • Geometry Fundamentals
  • Basic Processing Algorithms
  • Solving Laplace Equations
  • Advanced Methods

photo
reconstruction
3D print

Course Overview

  • Introduction
  • 3D Content Creation
  • Geometry Fundamentals
    1. Geometry Representations
    2. Differential Geometry
    3. Discrete Operators
  • Basic Processing Algorithms
  • 3D Content Creation
  • Solving Laplace Equations
  • Advanced Methods



Course Overview

  • Introduction
  • 3D Content Creation
  • Geometry Fundamentals
  • Basic Processing Algorithms
    1. Surface Reconstruction
    2. Delaunay Mesh Generation
    3. Smoothing
    4. Remeshing
  • Solving Laplace Equations
  • Advanced Methods

original
low-pass
exaggerate

Course Overview

  • Introduction
  • 3D Content Creation
  • Geometry Fundamentals
  • Basic Processing Algorithms
  • Solving Laplace Equations
    1. Parametrization
    2. Fairing & Deformation
    3. Geodesic Distances
  • Advanced Methods

parameterization
deformation
geodesic distances

Course Overview

  • Introduction
  • 3D Content Creation
  • Geometry Fundamentals
  • Basic Processing Algorithms
  • Solving Laplace Equations
  • Advanced Methods
    1. Quad Mesh Generation & Cross Fields

cross fields
quad meshing

Learning Outcomes

  • At the end of the course you will be able to:
    • Explain and contrast fundamental geometry representations
    • Explain and apply concepts from discrete differential geometry
    • Analyze the 3D content creation pipeline and understand its limitations
    • Implement and evaluate basic geometry processing algorithms, such as smoothing, remeshing, deformation
    • Implement algorithms for advanced modeling
    • Create digital 3D models from photographs and process the acquired raw geometry to build physical prototypes
    • Coordinate a team during a software project

Practical Assignments

  • Programming and written exercises
    • implement fundamental algorithms for geometry analysis, smoothing, remeshing, editing
  • Must be done in groups of 3
  • All deadlines are strict!
    • Zero points when submitted after the deadline
    • Don’t wait until the last minute but submit version early. Can always be replaced by final version before deadline
    • Contact me early in case of military service, sick leave, etc.

Grading

  • Each assignment is worth 10 points
  • Admission to final exam requires 50% of total points
  • Final exam determines grade
  • Exams cover material from lectures and practical assignments
  • Zero tolerance for cheating!

At the end of the course you will …

At the end of the course you will …

… know how to express love with equations

At the end of the course you will …

… be able to untangle messy curves

At the end of the course you will …

… know why this can be made from a single sheet of paper

Eric Demaine

At the end of the course you will …

… know why this cannot be made from a single sheet of paper

At the end of the course you will …

… understand why at any time there is at least one point on the planet where there is no ground wind (and what that has to do with geometry)

wikimedia.org

At the end of the course you will …

… be able to figure out if the universe is flat (well, sort of)

wikipedia

At the end of the course you will …

… know how to properly eat pizza

wired.com

At the end of the course you will …

… know a lot more about soccer balls

At the end of the course you will …

… be able to play games with funky dice

wired.com

At the end of the course you will …

… know what the Fourier transform of a bunny looks like

At the end of the course you will …

… know how to skin a cow

At the end of the course you will …

… be able to make a Dino hatch from an egg

At the end of the course you will …

… have seen some very unique geometric objects

… and understand what they are good for

At the end of the course you will …

… understand why it’s hard to scan something

(but still scan some cool stuff)

At the end of the course you will …

… understand why it’s hard to 3D print something

(but still print some cool stuff)

At the end of the course you will …

… (hopefully) appreciate the beauty of geometry