Notes
Slide Show
Outline
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What’s going on in Computer Vision at the University of Maryland
  • David Jacobs
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What I’m going to talk about
  • What computer vision is.
    • What vision is.
    • Computer vision.
  • Landscape of research at Maryland.
  • What it’s like to do vision research.
    • Tools used.
    • Research groups.
    • Future careers.
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Vision
  • ``to know what is where, by looking.’’ (Marr).
  • Where
  • What


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Why is Vision Interesting?
  • Psychology
    • ~ 50% of cerebral cortex is for vision.
    • Vision is how we experience the world.
  • Engineering
    • Want machines to interact with world.
    • Digital images are everywhere.
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Vision is inferential: Light
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Vision is Inferential: Geometry
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Vision is Inferential
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Vision is Inferential: Prior Knowledge
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Computer Vision
  • Inference à Computation
  • Building machines that see
  • Modeling biological perception


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Vision at Maryland
  • Laboratory founded by Azriel Rosenfeld in 1965
    • One of (maybe the) oldest computer vision labs.
    • Many alumni throughout world.
  • Very big.
    • ~ Four teaching faculty, ~ Nine research faculty, ~40-50 grad students.
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Research Themes
  • Very diverse.
    • Understanding images of people.
      • Tracking: where are people? In what position?
      • Recognition: Activity; expression; identity.
    • Structure-from-motion.
      • 3D from video.
      • New cameras.
    • Document/video understanding
    • Recognition: lighting, shape.


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Visual Surveillance-Goals
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Background Subtraction
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Tracking and Activity Classification
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Reconstruction
  • Video
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Tracking – Commercial Application
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Tracking
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Tracking
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Tracking
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Tracking
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Motion – Commercial Application
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Recognition - Shading
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Classification
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Expression recognition
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What is it like to do computer vision?
  • A very diverse field
    • Important work comes from people belonging to many different fields: Computer Science; Electrical Engineering; pure math; applied math; physics; neuroscience; psychology.
    • Common language is math
    • Diversity of goals: building useful systems; understanding biological vision; fundamentals of vision; testbed for learning or optimization.
    • Diversity of tools: math; optimization; system building (including real time systems); AI; learning…
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Modes of Operation: Possible steps in doing a vision thesis
  • Starting points
    • A practical problem: activity recognition; leaf recognition; real-time tracking.
    • An unresolved issue in a fundamental problem: role of occlusions in stereo; effect of motion on pose and shading.
    • A technique: fast multipole methods; Kalman filtering; belief propagation.
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"First steps"
  • First steps:
    • Implement benchmark algorithms.
    • Find a simple, toy domain to solve mathematically
    • Look for flaws in current algorithms and try to improve them.
  • Influential work:
    • Solve a fundamental math problem, especially one that gives rise to new algorithm.
    • Show importance of technique from other field.
    • Create a new problem.
    • Build impressive system that demonstrates new ideas or potential effectiveness of existing ones.
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What makes a good vision researcher?
  • Core competency in many areas: programming, math, knowledge of other fields.
  • But can excel in many ways:
    • System building
    • Math/Algorithms
    • Vision and …(graphics, hci, psychology, learning).
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Where is Computer Vision Going?
  • More Data, Faster Machines =>
  • More Interaction with Other Fields.
  • Fundamental Problems Remain


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Optimization
  • Partly push of video meant bigger optimization problems.
  • Early 90s, SVD, Gradient Descent, Filtering.
  • More recently, Graph Algorithms, Particle Filtering, Mean-shift, Multi-grid, Fast Multipole Methods ….
  • Techniques from theoretical CS, applied math, physics, learning, ….
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Learning
  • Recognition using supervised learning.
    • Given examples of an object
    • Use classifiers: eg, SVMs, Winnow, Boosting.
  • Grouping using unsupervised learning.
    • Eg., E-M
  • Probabilistic Modeling
    • Eg., Graphical models, texture, ….
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Graphics
  • Common interest in modeling reflection, light, 3D shape.
  • Image-Based Rendering.
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"input"




  • input depth image novel view
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Biomedical Engineering
  • Segmentation
    • Identify organs to measure them.
    • Find tumors.
  • Tracking
    • Is a heart beating properly?  Is there dead tissue?
  • Registration/Matching.
    • Positions of Tumors in Surgery.
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Big Data Sets
  • Image Data Bases
    • Kodak, commercial data bases w/ tens of thousands of images.
    • Internet, with millions?
  • Satellite imagery (Petabytes).
    • Monitoring effects of climate change.
  • Custom Data Sets
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