Computer Vision Lecture #1
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Transcript of Computer Vision Lecture #1
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Computer VisionComputer VisionLecture #1Lecture #1
Hossam Abdelmunim1 & Aly A. Farag2
1Computer & Systems Engineering Department, Ain Shams University, Cairo, Egypt
2Electerical and Computer Engineering Department, University of Louisville, Louisville, KY, USA
ECE619/645 – Spring 2011
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Course OutlineCourse Outline
• Computer Vision– Focus is on basic computer vision skills– Tools for research
• Mathematical Background– Basic material
– Numerical/computational Skills
• Matlab– Quick prototyping– tool for checking out ideas
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Text BooksText Books
1. A Guided Tour of Computer Vision, by V. S. Nalwa,Addison-Wesley, 1993.2. Introductory Techniques for 3-D Computer Vision, by Emanuele Trucco, Alessandro Verri, Prentice-Hall, 1998.3. Multiple View Geometry, by Richard Hartley, Andrew Zisserman, Cambridge University Press, 2000, 2003.4. Numerical Recipes in C, by William Press et al., Cambridge Univ. Press, 1992.5. Pattern Classification and Scene Analysis, by Richard O. Duda, Peter E. Hart, John Wiley & Sons, 1973.
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Computer VisionComputer Vision
Computer vision basics– Image creation– Cameras, Eyes, Calibration– Features, correspondence– 3D vision– Optical Flow– Tracking– Compression, vision for content delivery
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MathematicsMathematics
Basic Mathematical tools– Linear systems, matrix decompositions– Vector space, Basis, eigenvalues, eigenvectors– Calculus: gradients, Taylor series, maxima
• Projective geometry– Homographies, projectivities, constraints– Fundamental matrix– Trifocal tensor
• Probability, Random Variables, Classification
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Numerical MethodsNumerical Methods
• Solving linear systems of equations• Matrix decompositions
– LU, Eigenvalue, SVD,• Optimization• Use Matlab as a tool to quickly try ideas• Familiarity with image types• “Practical computer vision”
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Problems we should be able to solveProblems we should be able to solve• Calibrate a camera• Rectify an image• Create a three dimensional reconstruction• Insert model into image• Track objects• Track people• Read papers on these topics and do thesis research
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Application Example-1Application Example-1
Detect ground plane in video andintroduce pictures on them
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Application Example-2Application Example-2
morphing: blending between two photographs
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Application Example-3Application Example-3
morphing: blending between two photographs
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Application Example-4Application Example-4
turning a collection of photographs into a 3D model
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Application Example-5Application Example-5
Tracking
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What is Vision?What is Vision?Recognize objects
– people we know– things we own
• Locate objects in space– to pick them up
• Track objects in motion– catching a baseball– avoiding collisions with cars on the road
• Recognize actions– walking, running, pushing
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Vision isVision is
• Deceivingly easy• Deceptive• Computationally demanding• Critical to many applications
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Vision is Deceivingly EasyVision is Deceivingly EasyWe see effortlessly
– seeing seems simpler than “thinking”– we can all “see” but only select gifted people can solve“hard” problems like chess– we use nearly 70% of our brains for visual perception!
• All “creatures” see– frogs “see”– birds “see”– snakes “see”
but they do not see alike
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Vision is DeceptiveVision is DeceptiveVision is an exceptionally strong sensation
– vision is immediate– we perceive the visual world as external to ourselves,
but it is a reconstruction within our brains– we regard how we see as reflecting the world “as it
is;” but human vision is• subject to illusions• quantitatively imprecise• limited to a narrow range of frequencies of radiation• passive
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Some IllusionSome Illusion
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Some IllusionSome Illusion
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Some IllusionSome Illusion
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Some IllusionSome Illusion
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Human Vision is PassiveHuman Vision is Passive• It relies on external energy sources(sunlight, light bulbs, fires) providing lightthat reflects off of objects to our eyes
• Vision systems can be “active” - carry theirown energy sources
– Radars– Bat acoustic imaging systems
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Spectral Limitation of Human VisionSpectral Limitation of Human Vision
• We “see” only a small part of the energyspectrum of sunlight
– we don’t see ultraviolet or lower frequencies of light– we don’t see infrared or higher frequencies of light– we see less than .1% of the energy that reaches our eyes
• But objects in the world reflect and emit energy in these and other parts of the spectrum