Describe the pinhole camera model.
- Real object
- Virtual image
- Pinhole
- Image plane
Main elements of the camera model.
- Optical center
- Image plane
- Optical axis
- Principal point
- Focal length
- Refrence systems (camera and real world)
Draw the model!
Why the projection matrix is useful? Derive the first form of the projection matrix.
The projection matrix describes how the 3D world is mapped onto the image plane.
- Consider the 2D plane and the virtual image
- Define some ratios: x = f*X/Z
- Compute Z*[X Y 1]
How to map points projected onto the image in pixels.
- Define conversion factors
2. u = π’0 + π₯π/w
Camera matrix.
…
What are the intrinsic parameters?
ππ’, ππ£, π’0, π£0, f
What are the extrinsic parameters?
β 3 for translations
β 3 for rotations
Define the relation between camera and world
Describe the thin lens model with a sketch.
Give the thin lens equation.
1/d0 + 1/d1 = 1/f
What is the effect of adding a barrier in front of the lens?
Reduce the circle of confusion.
Define the field of view.
Angle perceived by the camera.
π = arctan(π/2f) <- doubled
Problems of real lenses
Distortion:
β Radial: barrel, pincushion
β Tangential
Chromatic aberration
- Color fringes near the image edges
Definition of depth of field.
The depth in which we can neglect the presence of the circle of confusion.
