POV-Ray : Newsgroups : povray.beta-test : Camera vectors are not perpendicular Server Time: 23 May 2017 01:09:03 GMT
  Camera vectors are not perpendicular (Message 1 to 3 of 3)  
From: ThH
Subject: Camera vectors are not perpendicular
Date: 4 Mar 2016 03:18:18
Message: <56d8fe7a$1@news.povray.org>
scenes/camera/shear.pov

I'm wondering what's going on here...

==== [Parsing...] ==========================================================
File 'shear.pov' line 48: Parse Warning: Camera vectors are not 
perpendicular.
  Making look_at the last statement may help.

Snippet from shear.pov:

8< snip >8
camera {
         perspective //keyword is facultative in this case
         location CamLoc
         right     x*image_width/image_height
         angle 90
         transform Shear // comment out to see 'falling buildings'
         rotate <0,45,0>
         look_at CamLook
         }
8< snip >8

Command was:
thh@quadro:~/POVRAY_MASTER/share/povray-3.7/scenes/camera$ povray 
shear.pov +p -w320 -h240 -uv

Look_at _is_ last statement of the camera definition and -uv _is_ used.

Is the warning mentioned above really necessary?

-- 
Thorsten aka ThH


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From: clipka
Subject: Re: Camera vectors are not perpendicular
Date: 4 Mar 2016 07:23:14
Message: <56d937e2$1@news.povray.org>
Am 04.03.2016 um 04:19 schrieb ThH:
> scenes/camera/shear.pov
> 
> I'm wondering what's going on here...
> 
> ==== [Parsing...]
> ==========================================================
> File 'shear.pov' line 48: Parse Warning: Camera vectors are not
> perpendicular.
>  Making look_at the last statement may help.
...

In the vast majority of cases, camera vectors are intended to be
perpendicular, but there are ways to accidently screw this up, so
POV-Ray warns about this situation. Judging from the warning's wording,
the most common way people would screw this up in the past was to place
look_at before the up, right and/or direction vector.

In this particular case, the camera vectors are non-perpendicular by
intention, to demonstrate a way to implement a tilt-shift camera.


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From: ThH
Subject: Re: Camera vectors are not perpendicular
Date: 4 Mar 2016 08:40:11
Message: <56d949eb$1@news.povray.org>
Am 04.03.2016 um 08:23 schrieb clipka:

> In the vast majority of cases, camera vectors are intended to be
> perpendicular, but there are ways to accidently screw this up, so
> POV-Ray warns about this situation. Judging from the warning's wording,
> the most common way people would screw this up in the past was to place
> look_at before the up, right and/or direction vector.
>
> In this particular case, the camera vectors are non-perpendicular by
> intention, to demonstrate a way to implement a tilt-shift camera.

Thanks for your explanation clipka. Really don't want to mess around 
with anybody's intentions ;))


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