Dear all,
How are you!
I want to know the position of project plane in the context of
perspective projection. Where can find that in source codes? Or how can
I specify some parameters to simulate the effect of changing the focus
diatance when using rpict or rtrace?
Thank you in advance!
Qing
From: Qing Xu <[email protected]>
Date: Tue Oct 22, 2002 6:41:54 AM US/PacificFor this moment, I want to know the position of project plane in the
context of
perspective projection. I looked for inside the codes, but I did not
find. Where can I find that in source codes? Actually, we want to
simulate the effect for changing the focus distance with the fixed view
point. How to do that? Is the view point the perspective projection
center in Radiance? What is the real meaning for focus distance in
Radiance?
The Radiance image projection code is in "ray/src/common/image.c". A guide to the source tree may be found on the website under "Documents":
http://radsite.lbl.gov/radiance/refer/index.html
The "view center" as it's often called does not really exist in Radiance per se. In fact, one could argue that there is no such thing for a pinhole camera, which is what rpict simulates. In order to have depth of field, you have to have a sampled aperture and a focus distance, neither of which are present in the default Radiance view model. Instead, you give rpict a view origin (-vp Ox Oy Oz) and direction vector (-vd Dx Dy Dz), which says where the camera is looking from and the direction it is looking in.
To get motion blur, you need to sample over an aperature with a particular view center, and I wrote a script called "pdfblur" that does just this. You can pass the views produced by pdfblur to rpict or (preferably) pinterp to get a depth-of-field blurred image. See the pdfblur(1) man page for details. I will send you an example image generated with pdfblur and pinterp.
-Greg