In case anyone else will look, a 1995 paper by Kolb, Mitchel, Hanrahan - A Realistic Camera Model for Computer Graphics
describes a lens model of thickness t
and how to control the depth of the field itself.
ray tracing: "size" of the field of depth
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03-08-2022 - |
Question
How do I actually define the depth of the field, that is, the range of z-values where my objects would be in focus. That is, I want objects with z
-coords in [f-w,f+w]
to be in focus (camera coords), where f
is the focal length and w
is some predefined constant.
The way I do it now is I find a primary ray from lens center to P
(point on the focal plane, z=-f
), then shoot rays from random points L
on the lens to P
.
What I am seeing is that the implicit value w
is very small, so there is a very visible band where things are in focus, and everything near it and further is blurred. Now, I could play with d
(distance from lens to image plane) and aperture values to make a specific scene look OK, but I wanted to see some maths on how to solve this issue properly.
I've looked at several ray tracing books and they all skirt this issue.
La solution