camera simulation · 2019-04-23 · cs348b lecture 7 pat hanrahan / matt pharr, spring 2019 camera...
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CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Camera Simulation
ReferencesPhotography, B. London and J. UptonOptics in Photography, R. KingslakeThe Camera, The Negative, The Print, A. Adams
Pat Hanrahan / Matt Pharr, Spring 2019
Effect Cause
Field of view Film size, focal length Depth of field Aperture, focal lengthExposure Film speed, aperture, shutterMotion blur Shutter
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Cameras (5D integral)
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Cook, Porter, Carpenter, 1984 Mitchell, 1991
Depth of FieldMotion Blur
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Topics
Lenses
Depth of field
Exposure
Light field cameras
Pat Hanrahan / Matt Pharr, Spring 2019
Lenses
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Pinhole Camera
Pat Hanrahan / Matt Pharr, Spring 2019
From Pharr et al. Physically Based Rendering (3rd Edition)
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Lenses Focus!
Rays from a point in object space intersect at a point in image space
These are conjugate points
Points at infinity converge at the focal point or focus
Points on different object planes focus on different image planes
The position of the point of focus can be changed by moving the lens
Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Gauss’ Ray Tracing Construction
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Parallel Ray
Focal Ray Chief Ray
Object Image
Focal Point
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Snell’s Law
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Law of Refraction
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Total internal reflection:
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Optical Manhole
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
From Livingston and Lynch
Total internal reflection
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Refraction at a Spherical Lens
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
n : index of refraction
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Snell’s Law
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Angle of Incidence
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
The sum of the interior angles is equal to the exterior angle.
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Angle of Refraction
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Opposite angles are equals
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Snell’s Law
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Paraxial Approximation: Small Angles
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Rays deviate only slightly from the axis
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Paraxial Approximation: Small Angles
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Angles to Slopes
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Gauss’ Formula
Paraxial approximation to Snell’s Law
Ray coordinates
Pat Hanrahan / Matt Pharr, Spring 2019
Holds for any height, any ray!
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Perspective Transformation
How does z transform?
Represent lens transformation as a 4x4 matrix
Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Ray Tracing: Finite Aperture
1. Pick a point on image plane x’
2. Pick a point on the lens u
3. Map x’ to x on the focal plane; form ray (u,x-u)
Pat Hanrahan / Matt Pharr, Spring 2019
Focal Plane Image PlaneAperture Plane
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Real Lens
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Cutaway section of a Vivitar Series 1 90mm f/2.5 lensCover photo, Kingslake, Optics in Photography
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Double Gauss
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Data from W. Smith, Modern Lens Design, p 312
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Ray Tracing Through Lenses
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
From Kolb, Mitchell and Hanrahan (1995)
200 mm telephoto
50 mm double-gauss
35 mm wide-angle
16 mm fisheye
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Ray Tracing Through Lenses
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
From Kolb, Mitchell and Hanrahan (1995)
Depth of Field
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Depth of Field
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
From London and Upton
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Circle of Confusion
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Circle of confusion proportional to the size of the aperture
Focal Plane Back Plane
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Resolving Power
Diffraction limit
35mm film (Leica standard)
CCD/CMOS pixel aperture
Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Bokeh
Pat Hanrahan / Matt Pharr, Spring 2019
Exposure
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Image Irradiance
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Relative Aperture or F-Stop
F-Number and exposure:
Fstops: 1.4 2 2.8 4.0 5.6 8 11 16 22 32 45 64
1 stop doubles exposure
Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019CS348b Lecture 7
Camera Exposure
Exposure
Exposure overdetermined
Aperture: f-stop - 1 stop doubles HDecreases depth of field
Shutter: Doubling the open time doubles HIncreases motion blur
Pat Hanrahan / Matt Pharr, Spring 2019
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
Aperture vs Shutter
CS348b Lecture 7 Pat Hanrahan / Matt Pharr, Spring 2019
From London and Upton
f/161/8s
f/41/125s
f/21/500s
Constant Exposure
Light Field Cameras
https://www.wired.com/2011/10/cross-section-shows-lytro-light-field-cameras-insides/
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