Hello !!

Today I was thinkering about camera reference frames and I had a little bit of
confusion.
Which three vectors define the frame of reference of the camera? I took as
granted that the z direction  was the one exiting from the camera, so the result
of the difference between the vectors "look_at" and "location". But in this way
the "right" and "up" directions (both defined or as default) are not
perpendicular to the z direction. So what is it? Are the right and up directions
(and the cross product of them) the reference frame of the camera (so the z
direction is not perpendicular to the image plane) or is it otherwise and the
right and up direction are not defining the camera reference frame?


Thanks in advance !!!!

Post a reply to this message

hi,

"Francescodario Cuzzocrea" <fra### [at] mailpolimiit> wrote:
> Today I was thinkering about camera reference frames and I had a little bit of
> confusion.
> Which three vectors define the frame of reference of the camera? ...

<http://wiki.povray.org/content/Reference:Camera#Placing_the_Camera>


regards, jr.

Post a reply to this message

Le 2020-02-13 à 08:37, Francescodario Cuzzocrea a écrit :
> 
> Hello !!
> 
> Today I was thinkering about camera reference frames and I had a little bit of
> confusion.
> Which three vectors define the frame of reference of the camera? I took as
> granted that the z direction  was the one exiting from the camera, so the result
> of the difference between the vectors "look_at" and "location". But in this way
> the "right" and "up" directions (both defined or as default) are not
> perpendicular to the z direction. So what is it? Are the right and up directions
> (and the cross product of them) the reference frame of the camera (so the z
> direction is not perpendicular to the image plane) or is it otherwise and the
> right and up direction are not defining the camera reference frame?
> 
> 
> Thanks in advance !!!!
> 
> 
In the default camera, up is +y and right is along the x axis, making 
them all perpendicular.

The frame of reference is the rectangle of size right by up situated at 
distance direction from the camera's location, unless you use the angle 
parameter. In that case, the size of the frame is adjusted as needed to 
ensure that right is correct relative to angle.

Post a reply to this message

"Francescodario Cuzzocrea" <fra### [at] mailpolimiit> wrote:
> Hello !!
>
> Today I was thinkering about camera reference frames and I had a little bit of
> confusion.
> Which three vectors define the frame of reference of the camera? I took as
> granted that the z direction  was the one exiting from the camera, so the result
> of the difference between the vectors "look_at" and "location". But in this way
> the "right" and "up" directions (both defined or as default) are not
> perpendicular to the z direction. So what is it? Are the right and up directions
> (and the cross product of them) the reference frame of the camera (so the z
> direction is not perpendicular to the image plane) or is it otherwise and the
> right and up direction are not defining the camera reference frame?
>
>
> Thanks in advance !!!!

http://news.povray.org/povray.binaries.images/thread/%3Cweb.5d881ea3763463c54eec112d0%40news.povray.org%3E/

http://news.povray.org/povray.binaries.images/thread/%3Cweb.5880b8311652a4dcc437ac910%40news.povray.org%3E/

The camera defaults are pretty straightforward, it's only once you start moving
things around that it can get tricky.

I would also take a look at the screen.inc file - as that has a lot of
definitions and transformations in it that can be instructive.

and links in this thread:
http://news.povray.org/povray.general/thread/%3Cweb.5b9ed475f76fb4baa47873e10%40news.povray.org%3E/?mtop=424446

and maybe you may find _something_ of use here:

http://news.povray.org/povray.binaries.images/thread/%3C5baddad1%40news.povray.org%3E/?mtop=424795

Post a reply to this message