US6028606A
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Camera simulation system
Assignee: Leland Stanford Junior University
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Filing: 1997-08-01
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Granted: 2000-02-22
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Expires: 2017-08-01
Abstract
Abstract A physical camera is modeled to render an image in a computer graphics system. When given the manufacturer's specifications of the physical camera's lenses, including the dimensions and indices of refraction of its lenses, stops, and shutter characteristics, the location of the film surface relative to the lens system, and the orientation of the camera within the scene, the invention accurately and efficiently mimics the physical principles of image formation creating an image which approximates an image produced by the physical camera. The procedure comprises four main elements: (1) the geometric relationships between the lens system, object, and film plane are modeled by precise placement and movement of lens elements, (2) image geometry is computed by using principles of geometric optics, (3) an exit pupil is calculated in order to define a region for efficiently sampling rays, (4) the image irradiance, or exposure at a pixel, is computed according to radiometric principles.
Inventors
- 👤 Craig E. Kolb
- 👤 Patrick M. Hanrahan
- 👤 Donald P. Mitchell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:51
CPC Classifications
G; G06; G06T; G06T15/00; G06T15/50; G06T15/06
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
128 words
A computer implemented method for rendering a three dimensional scene to generate a two dimensional image, the method comprising the steps of: (a) computing an exit pupil of a lens system; (b) selecting a ray that passes through the exit pupil to an image point on an image plane; (c) tracing the ray from the three dimensional scene through the lens system to the image point; (d) calculating a radiance value for the ray; wherein the calculation of the radiance value for the ray in step (d) comprises setting the radiance value to zero if the ray is vignetted; (e) repeating steps (b)-(d) to obtain a plurality of radiance values; and (f) combining the plurality of radiance values to generate the two dimensional image on the image plane.
Claim 2
Dependent Claim
128 words
A computer implemented method for rendering a three dimensional scene to generate a two dimensional image, the method comprising the steps of: (a) computing an exit pupil of a lens system; (b) selecting a ray that passes through the exit pupil to an image point on an image plane; (c) tracing the ray from the three dimensional scene through the lens system to the image point; (d) calculating a radiance value for the ray; wherein the calculation of the radiance value for the ray in step (d) comprises setting the radiance value to zero if the ray is vignetted; (e) repeating steps (b)-(d) to obtain a plurality of radiance values; and (f) combining the plurality of radiance values to generate the two dimensional image on the image plane.
Claim 3
Dependent Claim
29 words
The method of claim 1 wherein the calculation of the radiance value for the ray in step (d) comprises calculating an attenuation due to losses in the lens system.
Claim 4
Dependent Claim
30 words
The method of claim 1 wherein the ray tracing in step (c) comprises the calculation of a 4×4 projective transformation corresponding to a thick lens approximation of the lens system.
Claim 5
Dependent Claim
31 words
The method of claim 1 wherein steps (c) and (d) are performed in dependence upon a wavelength of the ray, whereby rays of differing wavelength may be selected in step (b).
Claim 6
Dependent Claim
32 words
The method of claim 1 wherein the combining of the radiance values in step (f) comprises evaluating, for each image point, an approximation to an integral of radiances over the exit pupil.
Claim 7
Dependent Claim
29 words
The method of claim 1 wherein the selecting of the ray in step (b) is performed in accordance with a measure preserving mapping of a square to a disk.
Claim 8
Dependent Claim
157 words
A computer implemented method for rendering a synthetic two dimensional image of a three dimensional scene in a manner that accurately simulates a physical lens system, the method comprising the steps of: (a) computing an exit pupil of the lens system; (b) selecting a ray that passes through the exit pupil from a point on the image surface; (c) tracing the ray through the lens system to determine an ultimate direction of the ray in object space; (d) repeating steps (b)-(c) to obtain a first plurality of directions for a first plurality of rays; (e) computing from the first plurality of rays and the first plurality of directions a selected second plurality of rays and a second plurality of directions; wherein step (e) includes the use of a thick lens approximation; (f) calculating radiance values for the second plurality of rays; and (g) combining the plurality of radiance values to compute an image value at each pixel.
Claim 9
Dependent Claim
157 words
A computer implemented method for rendering a synthetic two dimensional image of a three dimensional scene in a manner that accurately simulates a physical lens system, the method comprising the steps of: (a) computing an exit pupil of the lens system; (b) selecting a ray that passes through the exit pupil from a point on the image surface; (c) tracing the ray through the lens system to determine an ultimate direction of the ray in object space; (d) repeating steps (b)-(c) to obtain a first plurality of directions for a first plurality of rays; (e) computing from the first plurality of rays and the first plurality of directions a selected second plurality of rays and a second plurality of directions; wherein step (e) includes the use of a thick lens approximation; (f) calculating radiance values for the second plurality of rays; and (g) combining the plurality of radiance values to compute an image value at each pixel.
Claim 10
Dependent Claim
32 words
The method of claim 7, wherein step (f) comprises setting the radiance value to zero when a ray is vignetted by a shutter, aperture, stop, or other part of the camera system.
Claim 11
Dependent Claim
17 words
The method of claim 7, wherein attenuation in the lens system is accounted for in step (f).
Claim 12
Dependent Claim
24 words
The method of claim 7, wherein wavelength is accounted for in steps (c)-(g), whereby rays of different wavelengths may be selected in step (b).
Claim 13
Dependent Claim
19 words
The method of claim 7, wherein (g) comprises weighting the radiance values associated with rays in close proximity identically.
Claim 14
Dependent Claim
21 words
The method of claim 7, wherein (g) includes the use of the differential form factor from a point to a disk.
Claim 15
Dependent Claim
17 words
The method of claim 7, wherein (g) includes computing a separate weighting value for each radiance value.
Claim 16
Dependent Claim
18 words
The method of claim 7, wherein the two sets of rays and directions in step (e) are identical.
Claim 17
Dependent Claim
15 words
The method of claim 7, wherein step (e) includes the use of an approximating function.
Claim 18
Dependent Claim
21 words
The method of claim 7, wherein step (e) includes the use of a function that interpolates the plurality of ray directions.
Claim 19
Dependent Claim
15 words
The method of claim 7, wherein step (e) includes the use of a linear transformation.
Claim 20
Dependent Claim
15 words
The method of claim 7, wherein step (f) further comprises the interpolation of vignetting information.
Claim 21
Dependent Claim
13 words
The method of claim 7, wherein rays in are selected using pseudo-random sampling.
Claim 22
Dependent Claim
12 words
The method of claim 7, wherein rays are selected using stratified sampling.
Claim 23
Dependent Claim
17 words
The method of claim 7, wherein rays are selected by stratifying the pupil and image dimensions independently.
Claim 24
Dependent Claim
12 words
The method of claim 7, wherein rays are selected using quasirandom sampling.
Claim 25
Dependent Claim
20 words
The method of claim 7, wherein the mapping from a square domain to the domain of the pupil is measure-preserving.
Claim 26
Dependent Claim
12 words
The method of claim 7, wherein rays are selected using importance sampling.
Claim 27
Dependent Claim
124 words
A computer implemented method for rendering a three dimensional scene to generate a two dimensional image, the method comprising the steps of: (a) computing an exit pupil of a lens system, wherein the exit pupil defines a boundary between rays blocked by the lens system and rays passing through the lens system; (b) selecting a ray that passes through the exit pupil to an image point on an image plane; (c) tracing the ray from the three dimensional scene through the lens system to the image point; (d) calculating a radiance value for the ray; (e) repeating steps (b)-(d) to obtain a plurality of radiance values; and (f) combining the plurality of radiance values to generate the two dimensional image on the image plane.
Claim 28
Dependent Claim
124 words
A computer implemented method for rendering a three dimensional scene to generate a two dimensional image, the method comprising the steps of: (a) computing an exit pupil of a lens system, wherein the exit pupil defines a boundary between rays blocked by the lens system and rays passing through the lens system; (b) selecting a ray that passes through the exit pupil to an image point on an image plane; (c) tracing the ray from the three dimensional scene through the lens system to the image point; (d) calculating a radiance value for the ray; (e) repeating steps (b)-(d) to obtain a plurality of radiance values; and (f) combining the plurality of radiance values to generate the two dimensional image on the image plane.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-02-21 | 2003-08-23 | 2004-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-02-21 | 2007-08-23 | 2008-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-02-21 | 2011-08-23 | 2012-02-22 | $7700.00 | Window Closed / Lapsed |