Presentaci

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Tutorial Visual Perception

1. Towards Computer Vision
2. Steps in 3D Object Modelling
3. Camera Modelling and Calibration
4. StereoVision Epipolar Geometry
5. Fundamental Matrix Estimation
6. Coded Structured Light

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• Human Vision
• Identify objects
• Locate its 3D position.

Image acquisition
Image interpretation
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The Human Eye ?

• Eye shape
• Cornea Transparent surface.
• Sclera Outer cover composed of a fibrous coat
  that surrounds the choroid.
• Choroid a layer of blood capillaries.
• Retina layer inside the choroid composed of two
  types of receptors (rods and cones) and a netword
  of nerves.
• Optic nerve Retinal nerves leave the eye to the
  brain trough the optic nerve bundle.

• Image enhancement
• Cornea Transparent surface.
• Lens Focuses the light to the retina surface to
  perform proper focus of near and distant objects.
• Iris Acts as a diaphragm to control the amount
  of light entering the eye.

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How an eye is working ?

• Image acquisition
• Retina Composed of
• 100 M. Rods Long slender receptors.
• Sensitive at low levels of light.
• 6.5 M. Cones. Shorter and thicker receptors.
• Sensitive at high levels of light.
• Greatest presence at the Fovea region (sharpest
  vision).
• Three types of cones with different wavelength
  absorption with peaks in the blue, green and red
  light spectrum
• Light stimulus activate a rod or cone producing
  a nerve impulse which is transmitted through the
  optic nerve.

More information at http//www.vision.ca/eye/lobb
y.html
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Computer Vision Object Recognition. Object
Localisation. Advantage Automatisation. Constrai
nt Difficult to transmit the human intelligence
and skills to a computer. Applications Shape
Inspection for quality control Rapid
Prototyping Computer assisted surgery Film making
effects Object picking Robot Navigation
Image acquisition
?
?
Image interpretation
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3D Information
System selection
Modelling
Calibration
Correspondence
Get 3D Cloud
Data Fusion
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System Selection

• Combination of computational and optical
  techniques aimed at estimating or making explicit
  geometric (3D shape) properties of objects or
  scenes from their digital images.
• stereovision
• pattern projection
• laser scanning
• shape from X (motion, texture, shading, focus,
  zoom)
• Computation for all or some pixels of the
  distance between a known reference frame and the
  scene point that is imaged in those pixels. The
  output is a range image (depth map) or a cloud of
  points (xi, yi, zi), i1..N.
• The fusion of several range images or point
  clouds corresponding to partially different views
  of an object may yield its full 3D digitization.

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Main processes in 3D digitization
solid(triangles)
graphicsurface
N 3D point clouds
Range sensing
Geometric fusion
Objectmodeling
object
solid (splines)
System Selection
best nextview
Sensorplanning

• Stereovision
• Pattern projection
• Laser scanning
• Shape from X
• (motion, texture, shading, focus, zoom)

Texturemapping
coloured solid
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Geometric fusion
24 aligned 3D scans ready for merging
set of six 3D scans acquired from different
viewpoints and their alignment (center)
24 meshes merged into a surface triangulation.
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Applications
Dense reconstruction Visual
inspection Object localization Camera
localization