1. RAYS (Render As You See)
Vision-Realistic Rendering Using Hartmann-Shack Wavefront Aberrations
Brian A. Barsky Daniel D. Garcia Stanley A. Klein Woojin M. Yu Billy P. Chen Sarang S. Dalal
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2. Motivation
CWhatUC
ray tracing approach similar to Kolb, but with corneal topography
3 Major Limitations
computation time
small light sources
artifacts from the model
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3. The Algorithm (our goal)
color image with depth values
fixation point and wavefront data
generate an image with depth of field and visual artifacts consistent with the wavefront
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4. Hartmann-Shack Device
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5. Hartmann-Shack Device
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6. Hartmann-Shack Device
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8. Resampling Hartmann-Shack wavefront data
encodes gradient/slope of wavefront
however, sampling is very sparse!
Solution: fit a Zernike polynomial to these samples
resample at higher rate
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9. Point Spread Function 2D Retinal energy histogram
PSF as a blur filter and subsequent convolution with image
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10. Object-Space Point Spread Function (OSPSF)
analog to the traditional PSF used for wavefronts
image-space PSF vs. object-space OSPSF
array of OSPSF’s at each depth plane
OSPSF as a generalization of PSF
lens to pick fixation point
at each depth plane, a tuned diverging lens converts a wavefront converging at that depth to a plane wave
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11. Depth Planes
A person with 20/20 vision can perceive a subtended angle of one minute
 = pD
Assuming a typical pupil diameter of 2.4mm
D = 0.12 diopters
We use D = 0.25 diopters, but the maximum error is half the chosen precision
Consider a point 1.6 meters away from the lens
optometrists typically use 0.25 diopter increments for corrective lenses
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12. Depth Planes The range of sharp human vision is 10cm to infinity
At 0.25 diopter increments, we use 41 depth planes spaced from 0D (infinitely far) to 40D (10 cm)
Depth planes are placed densely closer to the observer, and more sparsely as it approaches infinity
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13. Rendering Image
PRMan
RGBZ values
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14. Stratification
image pixels are separated according to depth values into “depth strata”
continuous depth values are quantized into discrete values
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15. Convolution and Accumulation
OSPSF’s are convolved with each appropriate depth strata
Blurred images corresponding depth planes are accumulated together
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16. Example Images
Cubes
Road to Pt. RAYS
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18. Conclusion Vision-realistic Rendering Render As You See (RAYS)
Example images
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