Cameras ! ! First photograph due to Niepce ! ! First on record - - PowerPoint PPT Presentation

cameras
SMART_READER_LITE
LIVE PREVIEW

Cameras ! ! First photograph due to Niepce ! ! First on record - - PowerPoint PPT Presentation

Cameras ! ! First photograph due to Niepce ! ! First on record shown in the book - 1822 ! ! Basic abstraction is the pinhole camera ! ! lenses required to ensure image is not too dark ! ! various other abstractions can be


slide-1
SLIDE 1

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Cameras !

  • ! First photograph due to Niepce!
  • ! First on record shown in the book - 1822!
  • ! Basic abstraction is the pinhole camera!

–! lenses required to ensure image is not too dark! –! various other abstractions can be applied!

slide-2
SLIDE 2

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Image Formation !

  • ! Optics (geometry)!
  • ! Photometry (physics)!
slide-3
SLIDE 3

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

La “camera ottica” !

  • ! Conosciuta sin dall’antichita’ (Aristotele ne

accenna l’esistenza nel 330 a.C.), e’ l’antenato della moderna macchina fotografica!

slide-4
SLIDE 4

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Camere oscure negli USA !

slide-5
SLIDE 5

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Camera Obscura, Reinerus Gemma- Frisius, 1544 !

slide-6
SLIDE 6

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Camera Obscura, Athanasius Kircher, 1646 !

slide-7
SLIDE 7

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

  • ! Camera oscura a!
  • ! San Francisco!
slide-8
SLIDE 8

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

slide-9
SLIDE 9

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Camere oscure nel mondo … !

slide-10
SLIDE 10

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

… e in Italia (Rocca di Sanvitale, Fontanellato, Parma) !

slide-11
SLIDE 11

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Pinhole cameras !

  • ! Abstract camera model -

box with a small hole in it!

  • ! Pinhole cameras work in

practice!

slide-12
SLIDE 12

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

The equation of projection !

slide-13
SLIDE 13

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

The equation of projection !

  • ! Cartesian coordinates:!

–! We have, by similar triangles, that (x, y, z) -> (f x/z, f y/z, -f)! –! Ignore the third coordinate, and get!

slide-14
SLIDE 14

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Geometric properties of projection !

  • !

Points go to points!

  • !

Lines go to lines!

  • !

Planes go to whole image!

  • !

Polygons go to polygons!

  • ! Degenerate cases!

–! line through focal point to point! –! plane through focal point to line!

slide-15
SLIDE 15

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Polyhedra project to polygons !

  • ! (because lines project to

lines)!

slide-16
SLIDE 16

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Parallel lines converge !

slide-17
SLIDE 17

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Distant objects are smaller !

slide-18
SLIDE 18

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Orthographic projection !

slide-19
SLIDE 19

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Pinhole too big -! many directions are! averaged, blurring the! image! Pinhole too small-! diffraction effects blur! the image! Generally, pinhole ! cameras are dark, because! a very small set of rays! from a particular point! hits the screen.!

slide-20
SLIDE 20

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

The reason for lenses !

slide-21
SLIDE 21

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Thin lenses !

slide-22
SLIDE 22

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

slide-23
SLIDE 23

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Basic radiometry !

slide-24
SLIDE 24

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

slide-25
SLIDE 25

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Cameras !

slide-26
SLIDE 26

Computer Vision - A Modern Approach ! Set: Cameras ! Slides by D.A. Forsyth

!

Digital images !