Thorsten Froehlich <tho### [at] trfde> wrote:
> alex wrote:
> > Could it be that the focal blur ignores the director vector's direction?
>
> That is how it is documented ;-)
> http://www.povray.org/documentation/view/3.6.1/248/
>
>  Thorsten

I think that you cannot specify a non-perpendicular direction vector using
look_at *and* direction (I don't have sources handy to check that), but using
transform you do and that's why I didn't get different result varying the
direction vector.

The camera specification I was using was:
camera {
        perspective //keyword is facultative in this case
        location <50,10,30>
        direction vnormalize(Direction)
        look_at <0,10,0>
        blur_samples 120 //add samples if you got a fast computer
        aperture 10
        focal_point <5,10,5>
}
(from focalblur.pov)

whatever Direction is, the plane of focus does not change.

But if I use this specification:
#declare S_angle=(CamLook.y-CamLoc.y)/CamLoc.z;

#declare Shear= transform {
   matrix <  1,  0,  0,
             0,  1,  -S_angle,
             0,  0,  1,
             0,  0,  0 >
}
camera {
        perspective //keyword is facultative in this case
        location CamLoc
        angle 90
        transform Shear // comment out to see 'falling buildings'
        rotate <0,45,0>
        look_at CamLook

        blur_samples 120 //add samples if you got a fast computer
        aperture 10
        focal_point CamLook
        }
(from shear.pov)

the focal plane is *not* parallel to the image plane.
Just add focal blur to the shear.pov example scene and see for yourself.

I think that the focal plane is (correctly) parallel to the image plane only
when the camera vectors are perpendicular.

Exactly what I was looking for. :)

Now, all I need is a ton of help in working out the transormations needed to
emulate a tilt/shift lens....any volunteers?

--alex

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