01 - introduction and overviewpanozzo/cg/01 - introduction, images.pdf · csci-ga.2270-001 -...

CSCI-GA.2270-001 - Computer Graphics - Fall 16 - Daniele Panozzo

01 - Introduction and Overview


Staff

http://cs.nyu.edu/~panozzo/

Daniele Panozzo

Lecturer

Zhenyi He

Assistant

https://snowymo.github.io/zhenyi-he/[email protected]@nyu.edu

http://cs.nyu.edu/~panozzo/

https://snowymo.github.io/zhenyi-he/

mailto:[email protected]?subject=

mailto:[email protected]


Who Am I?• Assistant Professor of Computer Science since February 2016


Graphics @ Courant

Denis Zorin Kenneth Perlin Daniele Panozzo

Geometry ProcessingDigital Fabrication

Architectural Geometry

Virtual RealityComputer/Human Interface

Animation

Fluid and Solid SimulationMicrostructures

Scientific Computing


What is Computer Graphics?

• In a broad sense is the use of a computer to create and manipulate images

• It involves a combination of hardware (input, processing, output) and software

• It can be 2D or 3D

• It is used in most electronic devices


Graphic Areas

Modelinghttps://www.youtube.com/watch?v=Udno6EA5lXY

https://www.youtube.com/watch?v=Udno6EA5lXY


Graphic Areas

Rendering


Graphic Areas

Animation


Graphic Areas

User Interaction

Copyright: Andrew Guyton


Graphic Areas

Virtual Reality

Copyright: Maurizio Pesce


Graphic Areas

Visualization


Graphic Areas

Image ProcessingBy IkamusumeFan - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=41790217


Graphic Areas

Geometry Acquisition

By Creative Tools from Halmdstad, Sweden - CreativeTools.se - VIUscan - Laser-scanned - ZPrinter - 3D printed - Viking Belt Buckle 24, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=12419129

http://www.agisoft.com

https://commons.wikimedia.org/w/index.php?curid=12419129

http://www.agisoft.com


Applications

Video Games

Copyright: Nintendo

Cartoons/Visual Effects/Films

Copyright: Blender Foundation


Applications

CAD/CAM Simulation

By Andreas Babucke - self made with EAS3, original upload at http://de.wikipedia.org/wiki/Bild:Lambda2_scherschicht.png, CC BY 3.0 de, https://commons.wikimedia.org/w/

index.php?curid=2999003


ApplicationsMedical Imaging Information Visualization

By Etan J. Tal - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?

curid=12743250

By Mcstol - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18553353


Two major approachesPer-pixel - “Raytracing”

By Henrik - Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=3869326

Per-object - “Rasterization”


Per-pixel

By Henrik - Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=3869326

• Easy to parallelize but hard to map to hardware

• Expensive!

• It can be extended to model many physical phenomena such as internal scattering, diffraction, reflections, etc.

• Used to obtain high quality images


Per-object

• Easy to map to hardware

• While it cannot model directly complex effects, we can approximate them

• Used in interactive applications (mostly)


Course Goals

• Study the fundamental mathematical concepts used in image synthesis algorithms

• Implement a basic rendering system based on ray tracing

• Implement two interactive applications based on object-order rendering (rasterization), one in 2D and one in 3D

• Apply these techniques in a final coding project


Final Coding Project

• Individual project, we will publish the rules later but you are essentially free to do whatever you want, as long as it requires computer graphics

• The project will be presented in a fast-forward session at the end of semester (3-5 minutes per project)

• The winner will be awarded with a paid trip to SIGGRAPH 2017!


SIGGRAPH 2017


Prerequisites• Linear Algebra

• We will quickly review the concepts that you need, if you are not familiar with basis, points, vectors, matrices and linear systems, please review it on the textbook (Chapter 2, 5)

• C++

• We will review the basic concepts of C++ next week, comparing them with Java. Keep this reference at hand http://www.cppreference.com

• Why C++?

• Git

• It will be used to distribute material and to deliver homework

http://www.cppreference.com


Organization• Communication through the course repository/website: https://

github.com/danielepanozzo/cg

• Mailing list (if you did not receive the test email, let me know)

• Weekly lecture: Mondays 7.10-9 PM

• Office hours:

• Daniele: Mondays 5PM-6PM - 715 Broadway, 12th floor

• Zhenyi: Thursdays 5PM-7PM - Room 412 Warren Weaver Hall

https://github.com/danielepanozzo/cg


Lectures

• I will upload the slides on the website before the class, so that you can directly annotate them

• For every class, I will always add references in the end to the textbook and/or external resources

• At the end of every lecture, I will quickly introduce the topic of the next lecture and give you pointers — you are encourage to take a look at the material before I present it in class


Lectures

• Please interrupt me at any time to ask questions


Material

Fundamentals of Computer Graphics, Fourth Edition 4th Edition by Steve Marschner, Peter Shirley

https://open.gl

https://www.wikipedia.org

https://www.amazon.com/s/ref=dp_byline_sr_book_1?ie=UTF8&text=Steve+Marschner&search-alias=books&field-author=Steve+Marschner&sort=relevancerank

https://www.amazon.com/Peter-Shirley/e/B00IZTGJ9O/ref=dp_byline_cont_book_2


GradingAssignment Topic Grade

1 Ray Tracing 17.52 Raster 2D 17.53 Raster 3D 17.54 Final Project 27.5

Total Exercises: 80%• Final Oral Exam: 20% (you must get at least 10% in the final to pass)

• You must pass the final to pass the class

• The oral exam will be recorded (if you don’t want to be recorded send me a private email before the end of the week)

• There will be optional tasks, that will allow you to recover points lost in the assignments


Policy

• You are encouraged to consult with your classmates/friends but collaboration in the assignments is NOT allowed

• You are not allowed to copy code online or use external libraries (except those provided in the class) for the first 3 assignments

• We will use plagiarism tools to validate all homework

• I am horrible with names but I would still like to make an effort, please help me :)


Course Schedule 1/2• 12 September: 01 - Intro, Basic Math Pointers, Images, Ray Tracing 1 (Chapters 1,2,3,4)

• 19 September: 02 - C++ and CMake quick intro (slides), primer linear algebra (Chapter 5)

• Assignment 1: Ray tracing (due in 3 weeks)

• 26 September: 03 - Ray tracing 2 and Shading (Chapers 4, 10)

• 3 October: 04 - Transformation matrices and affine spaces (Chapter 6)

• 17 October: 05 - Rasterization 1 (Chapter 8, 17)

• Assignment 2: 2D Vector graphics editor (due in three weeks)

• 24 October: 06 - Rasterization 2 (http://open.gl and Chapter 17)

• 31 October: 07 - Curves and Splines (Chapter 15)

• 7 November: 08 - Viewing Transformations (Chapter 7)

• Midterms grades

• Assignment 3: 3D Mesh viewer (due in two weeks)


Course Schedule 2/2• 14 November: 09 - Data structures and Implicit Modeling (Chapter 12, 22)

• Assignment 4: Final Project Discussion (due in 6 weeks)

• 21 November: 10 - Texturing 1: Textures and procedural noise (Chapter 11)

• 28 November: 11 - Animation and Quaternions (Chapter 16)

• 5 December: 12- Colors and Light (Chapter 18, 19, 20)

• 12 December: 13 - Texturing 2: UV Mapping and Bump mapping (Chapter 11)

• 13 December: 14 - Geometry Acquisition and Processing or Open Q&A for the projects

• 19 December: FINAL and project presentation


Break

• What do you prefer?

• Let me know after this 10 minutes break!


Basic Math• Sets

• Functions/Maps

• Interval

• Logarithm

• Solving quadratic equations

• Trigonometry

If you are not familiar with some of these topics, refresh them before the next class.


Images


Images

By The original uploader was Darth Stabro at English Wikipedia - Transferred from en.wikipedia to Commons by Pbroks13 using CommonsHelper., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15789788


Raster Devices

• Output

• 2D: Display (LCD,LED)

• 1D: Hardcopy (ink-jet, dye sublimation)

• Input

• 2D Array: digital camera

• 1D Array: scanner


Bayesian Color-Filter

By en:User:Cburnett - Own workThis vector image was created with Inkscape., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1496858


Pixel Coordinates - Raster Image

0,0

x=-0.5y=-0.5

0,3

3,0

Be Careful: Y is flipped

in some APIs


Pixel Values (Framebuffer format)

• 1-bit greyscale - text

• 8-bit RGB (24 bits) - web and email

• 8-bit RGBA (32 bits) - alpha channel, see next slide

• 16/24/32bits - high accuracy for photography and HDR


Monitors Intensity, Gamma Correction

• What is the minimal and maximal light intensity?

• The intermediate intensities are different for each person, and it is non-linear

• Monitors needs to be calibrated for a certain viewer, using a procedure called “Gamma Correction”

• The rule is simple: displayed intensity = (max intensity) * a�

Pixel Value


Gamma Correction

• Find the neutral gray:

• Compute

• The colors will not be uniform on normal screens, one of the major factor affecting the cost of screens is their ability to be consistent on all pixels!

By X-romix 10:00, 7 June 2008 (UTC), Updated by --Rubybrian (talk) 14:25, 14 September 2010 (UTC); Photographer: Toni Frissell - This file was derived from: Weeki Wachee spring 10079u.jpg, GFDL, https://commons.wikimedia.org/w/index.php?curid=4176109

0.5 = a�

� =ln 0.5

ln a


RGB vs CMYK colors• RGB is additive • CMYK is subtractive

By BenRG and cmglee - http://commons.wikimedia.org/wiki/File:CIE1931xy_blank.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=32158329

Calibration is very important!


Alpha Compositing

• A way to represent transparency

• The pixels of an image are blended linearly with the image below

c = ↵cnew

+ (1� ↵)cold

↵ = 1

↵ = 0

RGBA is very common, and you will use it often!


Image Formats• Lossy:

• jpeg - compact, introduces artifacts

• Lossless:

• png - common for web applications

• ppm - very simple, not compressed

• tiff - mostly scientific use


References

Fundamentals of Computer Graphics, Fourth Edition 4th Edition by Steve Marschner, Peter Shirley

Chapters 1,2,3

https://www.amazon.com/s/ref=dp_byline_sr_book_1?ie=UTF8&text=Steve+Marschner&search-alias=books&field-author=Steve+Marschner&sort=relevancerank

https://www.amazon.com/Peter-Shirley/e/B00IZTGJ9O/ref=dp_byline_cont_book_2

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