Introduction

3D Computer Visionand Video Computing Introduction

Instructor: Zhigang ZhuCity College of New [email protected]

CSc I6716Spring 2011

3D Computer Vision

Introduction

3D Computer Visionand Video Computing Course Information

n Basic Information:l Course participationl Books, notes, etc.l Web page – check often!

n Homework, Assignment, Examl Homework and examsl Grading

n Goall What I expect from youl What you can expect from mel Resources

3D Computer Visionand Video Computing Book

n Textbookl “Introductory Techniques for 3-D Computer Vision” Trucco

and Verri, 1998n Additional readings when necessary

l “Computer Vision – A Modern Approach” Forsyth and Ponce, 2003

l “Three-Dimensional Computer Vision: A Geometric Viewpoint” O. Faugeras, 1998

l “Image Processing, Analysis and Machine VIsion” Sonika, Hlavac and Boyle, 1999

n On-Line References

3D Computer Visionand Video Computing Prequisites

n Linear Algebran A little Probability and Statisticsn Programming Experience n Reading Literature (A little)n An Inquisitive Nature (Curiosity)n No Fear

3D Computer Visionand Video Computing Course Web Page

n Lectures available in Powerpoint formatn All homework assignments will be distributed over the webn Additional materials and pointers to other web sitesn Course bulletin board contains last minute items, changes

to assignments, etc.l CHECK IT OFTEN!l You are responsible for material posted there

http://www-cs.engr.ccny.cuny.edu/~zhu/CSCI6716-2011s/VisionCourse-Spring-2011.html

http://www-cs.engr.ccny.cuny.edu/~zhu/CSCI6716-2009/VisionCourse-Fall-2009.html

http://www-cs.engr.ccny.cuny.edu/~zhu/CSCI6716-2009/VisionCourse-Fall-2009.html

3D Computer Visionand Video Computing Course Outline

n Complete syllabus on the web pages (14 meets)n Rough Outline ( 3D Computer Vision):

Part 1. Vision Basics (Total 4) 1. Introduction (1) 2. Image Formation and Processing (1) (hw 1, matlab) 3-4. Features and Feature Extraction (2) ( hw 2)

Part 2. 3D Vision (Total 7) 5. Camera Models (1) 6. Camera Calibration (2)(hw 3) 7. Stereo Vision (2) (project assignments)

8. Visual Motion (2) (hw 4)

Part 3. Exam and Projects (Total 3) 9. Project topics and exam review/discussion (1) 10. Midterm exam (1) 11. Student Project presentations (1)

3D Computer Visionand Video Computing Grading

n Homework (4): 40%n Exam (midterm): 40%n Course Project + Presentation: 20%

l Groups (2-3 students) for discussionsl Experiments – independently + collaborativelyl Written Report - independently + collaboratively

n All homework must be yours….but you can work together until the final submission

n Teaching Assistant: l Mr. Wai L. Khoo <[email protected]>

3D Computer Visionand Video Computing C++ and Matlab

n C++ l For some simple computation, you may use C++

n Matlabl An interactive environment for numerical computationl Available on Computer Labs machines (both Unix and Windows)

u Matlab primer available on line (web page)u Pointers to on-line manuals also available

l Good rapid prototyping environment

n Use C++ and/or Matlab for your homework assignments and project(s); However Java will also be fine

3D Computer Visionand Video Computing Course Goals and Questions

n What makes (3D) Computer Vision interesting ?

l Image Modeling/Analysis/Interpretationu Interpretation is an Artificial Intelligence Problem

Sources of Knowledge in Vision Levels of Abstraction

u Interpretation often goes from 2D images to 3D structures since we live in a 3D world

l Image Rendering/Synthesis/Compositionu Image Rendering is a Computer Graphics problemu Rendering is from 3D model to 2D images

2D images

3D world

CVCG

3D Computer Visionand Video Computing Related Fields

n Image Processing: image to imagen Computer Vision: Image to modeln Computer Graphics: model to image

n Pattern Recognition: image to classl image data mining/ video mining

n Artificial Intelligence: machine smartsl Machine perception

n Photogrammetry: camera geometry, 3D reconstructionn Medical Imaging: CAT, MRI, 3D reconstruction (2nd meaning)n Video Coding: encoding/decoding, compression, transmission

n Physics & Mathematics: basicsn Neuroscience: wetware to concept

n Computer Science: programming tools and skills?

All three are interrelated!

AI

Applications

basics

3D Computer Visionand Video Computing Applications

n Visual Inspection (*) n Robotics (*)n Intelligent Image Toolsn Image Compression (MPEG 1/2/4/7)n Document Analysis (OCR)n Image and Video on the Webn Virtual Environment Construction (*)n Environment (*)n Media and Entertainmentn Medicinen Astronomyn Law Enforcement (*)

l surveillance, securityn Traffic and Transportation (*)n Tele-Conferencing and e-Learning (*)n Human Computer Interaction (HCI)

3D Computer Visionand Video Computing Job Markets

n Homeland Securityl Port security – cargo inspection, human ID, biometricsl Facility security – Embassy, Power plant, bank l Surveillance – military or civilian

n Media Productionl Cartoon / movie/ TVs/ photographyl Multimedia communication, video conferencing

n Research in image, vision, graphics, virtual realityl 2D image processingl 3D modeling, virtual walk-thorugh

n Consumer/ Medical Industriesl Video cameras, Camcorders, Video phonel Medical imaging 2D -> 3D

3D Computer Visionand Video Computing IP vs CV

n Image processing (mainly in 2D)l Image to Image transformationsl Image to Description transformationsl Image Analysis - extracting quantitative information from

images:u Size of a tumoru distance between objectsu facial expression

l Image restoration. Try to undo damageu needs a model of how the damage was made

l Image enhancement. Try to improve the quality of an image

l Image compression. How to convey the most amount of information with the least amount of data

3D Computer Visionand Video Computing What is Computer Vision?

Vision is the art of seeing things invisible.

-Jonathan Swift (1667-1745) "Thoughts on Various Subjects" Miscellanies in Prose and Verse (published with Alexander Pope), vol. 1, 1727

n Computer vision systems attempt to construct meaningful and explicit descriptions of the world depicted in an image.

n Determining from an image or image sequence:l The objects present in the scenel The relationship between the scene and the observerl The structure of the three dimensional (3D) space

3D Computer Visionand Video Computing Cues to Space and Time

n Spectral Characteristicsl Intensity, contrast, colors and theirl Spatial distributions

n 2D Shape of Contoursn Linear Perspectiven Highlights and Shadowsn Occlusionsn Organizationn Motion parallax and Optical Flown Stereopsis and sensor convergence

Directly Measurable in an Image

3D Computer Visionand Video Computing Cues to Space and Time

n Surface connectivityn 3D Volumen Hidden sides and partsn Identity (Semantic category)n Absolute Sizen Functional Propertiesn Goals, Purposes, and Intentsn Organizationn Trajectories

Inferred Properties

3D Computer Visionand Video Computing Cues to Depth

n Question:l How do we perceive the three-dimensional properties of

the world when the images on our retinas are only two-dimensional?

n Stereo is not the entire story!


n Monocular cues to the perception of depth in imagesl Interposition: occluding objects appear closer than occluded

objectsl Relative size: when objects have approximately the same

physical size, the larger object appears closerl Relative height: objects lower in the image appear closerl Linear Perspective: objects appear smaller as they recede into

the distanceu texture gradients

l Aerial Perspective: change in color and sharpness as object recede into the distance

l Illumination gradients: gradients and shadow lend a sense of depth

l Relative Motion: faster moving objects appear closer


n Physiological cues to depth:

l Focus (accomodation): change in curvature of the lens for objects at different depths

l Convergence: eyes turn more inward (nasal) for closer objects

l Retinal disparity: greater for objects further away

3D Computer Visionand Video Computing Interposition



3D Computer Visionand Video Computing Different viewpoint


Edgar Degas: Dance Class at the Opéra, 1872


Edgar Degas: Green Dancer,c.1880


Edgar Degas: Frieze of Dancers, c.1895

















3D Computer Visionand Video Computing Aerial Perspective

n Constable

3D Computer Visionand Video Computing Aerial Perspective

n Classic Chinese Paintings

3D Computer Visionand Video Computing Absolute Size

3D Computer Visionand Video Computing Relative Size


3D Computer Visionand Video Computing Absolute Size


3D Computer Visionand Video Computing Light and Surfaces






n C. H. Stoelting Company





3D Computer Visionand Video Computing The Effect of Perspective

3D Computer Visionand Video Computing Texture Gradient

Sunflowers in Fargo, NDPhoto by Bruce Fitz http://www.ars.usda.gov/is/graphics/photos/

3D Computer Visionand Video Computing Texture Gradients

3D Computer Visionand Video Computing Edges

3D Computer Visionand Video Computing Texture Edges

3D Computer Visionand Video Computing Who Knows

3D Computer Visionand Video Computing Next

Anyone who isn't confused really doesn't understand the situation.

--Edward R. Murrow

Next:Image Formation

Reading: Ch 1, Ch 2- Section 2.1, 2.2, 2.3, 2.5Questions: 2.1. 2.2, 2.3, 2.5Exercises: 2.1, 2.3, 2.4

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Introduction

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