Depth of Field Simulation

radiance-general
1

Hi, can anyone point me to an example of how to create a DOF effect with Radiance?
I tried reading the pdf/pinterp docs but am still not clear as to how the process works.

Thanks

2

You start with a view file with a single view in it, whose -vd direction vector length is the focus distance of the subject. You then pass this “viewfile” to pdfblur and pinterp like so:

pdfblur 0.05 50 viewfile | pinterp -vf viewfile -x xres -y yres -B render.hdr render.zbf > blurred.hdr

In this example, I am using a lens aperture of “0.05” in world units, whatever they are. You can also generate a depth-of-field blur using rpict directly:

rpict -vf viewfile -pd 0.05 -x 3000 -y 3000 [other options] scene.oct | pfilt -1 -x /3 -y /3 -r .6 > blurred.hdr

Rendering at a higher resolution and downsampling with pfilt greatly improves the quality of the results. You can also combine these methods, putting a little bit of noisy depth-of-field blur in with rpict then applying the faster pinterp method for the rest:

rpict -vf viewfile -pd 0.02 -x 2000 -y 2000 [other options] -o slightblur.hdr -z slightblur.zbf scene.oct
pdfblur 0.03 50 viewfile | pinterp -vf viewfile -x 2000 -y 2000 -B slightblur.hdr slightblur.zbf | pfilt -1 -x /2 -y /2 -r .6 > blurred.hdr

An important note about computing the aperture used by Radiance is given in the ranimate(1) manpage, which can perform the above operations as part of managing an animation:

To simulate a particular camera
aperture, divide the focal length of the lens by  the  f-number, 
then  convert  to  the  corresponding  world coordinate
units.  For example, if you wish to simulate a 50mm  lens  at
f/2.0  in  a scene modeled in meters, then you divide 50mm by
2.0 to get 25mm, which corresponds to an  effective  aperture
of  0.025  meters.

-Greg

3

What should I do if my image is created using rtrace, so there’s no defined view file? The reason is I’m also trying to simulate realistic lens distortion effect.

4

The view parameters can be approximate. You will need to add them to your rtrace output using getinfo -a, e.g.:

getinfo -a "VIEW= -vtv -vh 90 -vv 50 -vp 10 19 25 -vd -5 -3 -1.5" < rtrace_out.hdr > withview.hdr
5

Thanks for you answer.

I’m concerned about how well of an approximation that will be, but I’ll try it out.

I think it might be a nice feature to be able to interpolate by directly feeding rays into pinterp rather than view files, in order to allow arbitrary views.

Thanks