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Le 18-06-18 à 05:59, CrisDamian a écrit :
>
> I am trying to use a pair of datasets generated with POV-Ray(links below) in
> order to test a depth from defocus cue algorithm but I know almost nothing about
> POV-Ray and I can't figure out the parameters for the camera. What I need is:
>
> - The aperture diameter of the camera (it says on the site that it is 40 but
> that seems physically inaccurate).
That's NOT a diameter but that's about the horizontal field of view, in
degree, of the default camera.
> - The focal length of the lens.
> - The sampling period of the pixels.
>
> I have experimented a bit with the dataset, the code is on:
> https://github.com/CrisDamian/BlurEqualisationTechnique
>
> There is also an issue on this:
> https://github.com/CrisDamian/BlurEqualisationTechnique/issues/1
>
> Datasets:
> http://devernay.free.fr/vision/focus/patio/
> http://devernay.free.fr/vision/focus/office/
>
>
In POV-Ray, there is no real diameter for the camera and no real focal
length. Unless defined otherwise, it's an ideal pinhole camera.
When you want to enable focal blur, you need to define an arbitrary
aperture and set a focal point. The effective focal plane is
perpendicular to the line going from the camera to the focal point.
There is no concept of f stops.
The area of sharpness depend on the ratio between the aperture and the
distance from the camera location to the focal point
Sample camera with focal blur :
camera{location -20*z
up y // default
direction z // default
right 4/3*x // default if version <= 3.7
aperture 0.25
focal_point <0,0,0> // default
blur_samples 100// maximum number of samples to take.
confidence 0.99 //Must be less than 1
variance 1/256 //must NOT be zero
}
This setup result in a camera that is close to a camera at f80 with an
horizontal field of view of about 40°.
The samples are taken in a roughly circular pattern.
You can set a minimum number of samples by using two values for
blur_samples :
blur_samples 12, 100
The samples are simply averaged to get the final value for the current
pixel been rendered.
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