Camera Models and Imaging

Leow Wee Kheng CS4243 Computer Vision and Pattern Recognition Camera Models and Imaging CS4243 Camera Models and Imaging 1 Through our eyes…  ...
Author: Harriet Gibbs
166 downloads 0 Views 985KB Size
Leow Wee Kheng CS4243 Computer Vision and Pattern Recognition

Camera Models and Imaging

CS4243

Camera Models and Imaging

1

Through our eyes… 

CS4243

Through our eyes we see the world.

Camera Models and Imaging

2

cornea focus light lens retina captures image transmit image

optic nerves iris pupil control amount of light entering the eye

CS4243

Camera Models and Imaging

3

Through their eyes… 

CS4243

Camera is computer’s eye.

Camera Models and Imaging

4



Camera is structurally the same the eye. sensor | retina

lens lens | cornea CS4243

Camera Models and Imaging

5

lens

aperture | pupil

lens | cornea CS4243

Camera Models and Imaging

6

aperture plates | iris

aperture | pupil

CS4243

Camera Models and Imaging

7

Imaging 

Images are 2D projections of real world scene.



Images capture two kinds of information:  Geometric:

positions, points, lines, curves, etc.  Photometric: intensity, colour. 

Complex 3D-2D relationships.



Camera models approximate relationships.

CS4243

Camera Models and Imaging

8

Camera Models 

Pinhole camera model



Orthographic projection



Scaled orthographic projection



Paraperspective projection



Perspective projection

CS4243

Camera Models and Imaging

9

Pinhole Camera Model image plane

2D image

pinhole

virtual image plane

3D object

focal length

CS4243

Camera Models and Imaging

10



Math representation world frame / camera frame

camera centre CS4243

image frame

image centre Camera Models and Imaging

projection line

optical axis 11



CS4243

By default, use right-handed coordinate system.

Camera Models and Imaging

12



3D point P = (X, Y, Z)T projects to 2D image point p = (x, y)T .



By symmetry,

i.e.,



CS4243

Simplest form of perspective projection.

Camera Models and Imaging

13

Orthographic Projection

 3D

scene is at infinite distance from camera.  All projection lines are parallel to optical axis.  So,

CS4243

Camera Models and Imaging

14

Scaled Orthographic Projection

depth

Suggest Documents