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On 28/08/2014 17:32, Bald Eagle wrote:
> Thomas de Groot <tho### [at] degroot org> wrote:
> The diagram I saw of the perspective camera seemed to suggest that the direction
> vector is half the length of the camera to look_at length. True?
No. Look_at is only used for the alignment of the center of the image
with the line going from camera position to look_at position.
Direction can be used to provides some different angle values, as long
as angle is not specified.
See http://wiki.povray.org/content/Reference:Camera#Perspective_projection
> http://wiki.povray.org/content/Reference:Camera#Perspective_projection
When angle is specified, the up & right vectors are internally
recomputed from the direction vector (lengths are adjusted).
> The diagram didn't give a good explanation of right and up in relation to the
> image size.
up & right, in perspective camera, are irrelevant about the visible
field (but if the angle was not specified, the ratio between right &
direction will have an impact).
Ratio of up & right should matches the ratio of the image size time the
ratio of the pixel. (so with traditional square pixel, the ratio of up &
right should be identical to the height & width ratio )... time or
divide, I'm often confused, but square pixel have a nice 1, so it's
irrelevant most of the time for me.
Beware when comparing povray's camera's angle (of perspective camera)
and the photographic angle:
Povray's angle is the one between the horizontal picture dimension and
the opening of the prism, whereas the photographic is along the diagonal
(which means 1:2, 4:3 and 16:9 would have different angle to have the
same object on the left/right border)
>
> (I also have a Tina-CHeP question for you... how/where to do that?)
>
> Thanks a lot for the suggestions!
>
>
>
I have seen something like group irtc.general which talks about TC-RTC.
--
IQ of crossposters with FU: 100 / (number of groups)
IQ of crossposters without FU: 100 / (1 + number of groups)
IQ of multiposters: 100 / ( (number of groups) * (number of groups))
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