Camera Projections Before describing the forward projection Image - - PowerPoint PPT Presentation

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Camera Projections Before describing the forward projection Image - - PowerPoint PPT Presentation

Nov 13, 2022 177 likes •682 views

Camera Projections Before describing the forward projection Image formation How are objects in the world captured in an image? Image formation Lets design a camera Idea 1: put a piece of film in front of an object Do we

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Camera Projections

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Before describing the forward projection…

Image formation

  • How are objects in the world captured in an

image?

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Image formation

  • Let’s design a camera

– Idea 1: put a piece of film in front of an object – Do we get a reasonable image?

Slide by St

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Pinhole camera

Slide by Steve Seitz

  • Add a barrier to block off most of the rays

– This reduces blurring – The opening is known as the aperture – How does this transform the image?

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  • Add a barrier to block off most of the rays

– This reduces blurring – The opening is known as the aperture – How does this transform the image?

If we treat pinhole as a point, only one ray from any given point can enter the camera.

Slide by Steve Seitz

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  • Pinhole camera is a simple model to approximate

imaging process, perspective projection.

Fig from Forsyth and Ponce

If we treat pinhole as a point, only one ray from any given point can enter the camera.

Virtual image pinhole Image plane

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Camera obscura

"Reinerus Gemma-Frisius, observed an eclipse of the sun at Louvain on January 24, 1544, and later he used this illustration of the event in his book De Radio Astronomica et Geometrica, 1545. It is thought to be the first published illustration of a camera obscura..." Hammond, John H., The Camera Obscura, A Chronicle

http://www.acmi.net.au/AIC/CAMERA_OBSCURA.html

In Latin, means ‘dark room’

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Camera obscura

Jetty at Margate England, 1898.

Adapted from R. Duraiswami http://brightbytes.com/cosite/collection2.html

Around 1870s

An attraction in the late 19th century

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We will start here in the middle, since it relates to the image formation process we just discussed.

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