POV-Ray : Newsgroups : povray.pov4.discussion.general : camera calibration : Re: camera calibration Server Time 4 Dec 2023 02:11:33 EST (-0500)
 Re: camera calibration
 From: clipka Date: 14 Mar 2013 07:02:48 Message: <5141ae58\$1@news.povray.org>
Am 13.03.2013 22:43, schrieb StudentPHD:

> My problem is about the matrix K of internal parameters(3 by 3). It means the
> focal, size of pixel(is square or not?),...
>
> And Finally, I need the model used by povray to project the 3D point. I know
> that I use a perspective type of projetion but . There many manner to calculate
> the matrix of camera. like P=  k*[R T] , P=K*[R -R*T]. I need to know which
> model the pov ray software uses ?

The standard camera model used by POV-Ray is a simple pinhole camera,
with the pinhole being located exactly at the camera's nominal location.

The way you specified the camera (with an explicit angle), the camera is
presumed to have a distane between the "film" and the "lens" of 1
POV-Ray unit, and the "film" is supposed to have a size of tan(angle) by
tan(angle)*|up|/|right| POV-Ray units, divided into image_width by
image_height pixels.

If using focal blur, the camera is presumed to have a simple lens
instead of a pinhole, focusing the plane at a distance of
|focal_point-location| onto the "film" plane, but having otherwise
identical characteristics as the pinhole. The aperture is presumed to
have a (virtual) diameter of "aperture" POV-Ray units.

I /think/ that should give you all information required to compute the
K-matrix parameters - provided you know what the individual K-matrix
parameters actually mean, which I really absolutely don't.