01 - Introduction and Overviewpanozzo/cg18/Slides/01 - Introduction, Images.pdf · CSCI-GA.2270-001...

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

01 - Introduction and Overview


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!


SIGGRAPH


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

https://github.com/danielepanozzo/cg

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 encouraged 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 video 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 :)


Break

• What do you prefer?

• Let me know after this 10 minutes break!


Basic Math• Sets

• Functions/Maps

• Intervals

• Logarithm

• Solving Quadratic Equations

• Trigonometry

• Basic Linear Algebra

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

01 - Introduction and Overviewpanozzo/cg18/Slides/01 - Introduction, Images.pdf · CSCI-GA.2270-001...

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