POV-Ray : Newsgroups : povray.general : About camera reference frame Server Time: 28 Jan 2021 06:11:05 GMT
 About camera reference frame (Message 1 to 4 of 4)
 From: Francescodario Cuzzocrea Subject: About camera reference frame Date: 13 Feb 2020 13:40:00 Message:
```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?

```
 From: jr Subject: Re: About camera reference frame Date: 13 Feb 2020 14:35:00 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.
```
 From: Alain Martel Subject: Re: About camera reference frame Date: 14 Feb 2020 00:00:39 Message: <5e45e327\$1@news.povray.org>
```Le 2020-02-13 Ã  08:37, Francescodario Cuzzocrea a Ã©critÂ :
>
> 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?
>
>
>
>
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.
```
 From: Bald Eagle Subject: Re: About camera reference frame Date: 14 Feb 2020 02:05:01 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?
>
>

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.