Eero Ahonen wrote:
> Warp wrote:
>>
>>   Please read the caveats of that "trick" here:
>>
>> http://tag.povray.org/povQandT/languageQandT.html#aspectratio
>>
>
> Good points (except 1, which is poo, because rendering the scene with
> unoriginal/unintended aspect ratio always disturbs it, except with
> case 3 ;)), thou they haven't disturbed me yet (4. seems to be one
> that will). I usually render my scenes several times with multiple
> aspect ratios to get more view, which makes the automation handy.

As a side note, if you want an automatic adjustment for image ratio that 
doesn't prioritize either horizontal or vertical angle, you can use:

up y*sqrt(image_height/image_width)
right x*sqrt(image_width/image_height)

This will for example have the effect that if you switch the width and 
height of the image, it will be like if you rotated a real camera 90 
degrees: the area will be the same.

Remember though that the effect will be overruled if the angle keyword is 
used.

Rune
-- 
http://runevision.com

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Eero Ahonen wrote:
> Warp wrote:
>>
>>   Please read the caveats of that "trick" here:
>>
>> http://tag.povray.org/povQandT/languageQandT.html#aspectratio
>>
>
> Good points (except 1, which is poo, because rendering the scene with
> unoriginal/unintended aspect ratio always disturbs it, except with
> case 3 ;)), thou they haven't disturbed me yet (4. seems to be one
> that will). I usually render my scenes several times with multiple
> aspect ratios to get more view, which makes the automation handy.

Hmm these explanations have always seemed to me as giving reasons why the 
default behaviour of POV is wrong.

How about having a camera block where you specify the vertical FOV, and the 
default horizontal FOV is automatically calculated to give square pixels. 
But you can override it if you want.

That way would fix #2 about "panoramic" shots keeping the vertical FOV while 
you expand them.  It would also fix #3 because people could still render 
non-square if they really wanted.

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scott <sco### [at] spamcoom> wrote:
> How about having a camera block where you specify the vertical FOV, and the 
> default horizontal FOV is automatically calculated to give square pixels. 
> But you can override it if you want.

  How would you override the default pixel aspect ratio if so needed?

  Perhaps there could be an aspect ratio command-line parameter similar
to the one in mplayer.
  mplayer assumes by default that pixels are square and that the input
video is non-anamorphic. However, if it so happens that the input video
is anamorphic and it does not have this info in itself (as sometimes
happens when converting between video formats) you can specify the
aspect ratio of the input with the -aspect parameter (for example,
if the input has 4:3 video but which is actually a 16:9 video squeezed
into 4:3, thus making it anamorphic, you can specify "-aspect 16:9" to
mplayer and it will unsqueeze it to that aspect ratio).

-- 
                                                          - Warp

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>> How about having a camera block where you specify the vertical FOV,
>> and the default horizontal FOV is automatically calculated to give
>> square pixels. But you can override it if you want.
>
>  How would you override the default pixel aspect ratio if so needed?

By setting the horizontal FOV manually inside the camera block.  As I said, 
the default would be whatever angle is needed to make square pixels (so the 
majority of the time you wouldn't use it), but it is there if you want to 
set it yourself.

>  Perhaps there could be an aspect ratio command-line parameter similar
> to the one in mplayer.

Yes, that would also work.

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scott <sco### [at] spamcoom> wrote:
> >  How would you override the default pixel aspect ratio if so needed?

> By setting the horizontal FOV manually inside the camera block.

  No, I think it's a bad idea to force someone to modify the scene file
in order to render with non-square pixels.

  In some cases this may even be very unfeasible, such as when some
program has created some thousands of individual pov files to be rendered
(and form an animation). It would be very laborious to edit all of them
so that one could render with non-square pixels.
  But even if it's just one file, I still think it's not a good idea.

-- 
                                                          - Warp

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Warp wrote:
> scott <sco### [at] spamcoom> wrote:
>>>  How would you override the default pixel aspect ratio if so needed?
>
>> By setting the horizontal FOV manually inside the camera block.
>
>  No, I think it's a bad idea to force someone to modify the scene file
> in order to render with non-square pixels.
>
>  In some cases this may even be very unfeasible, such as when some
> program has created some thousands of individual pov files to be
> rendered (and form an animation). It would be very laborious to edit
> all of them so that one could render with non-square pixels.
>  But even if it's just one file, I still think it's not a good idea.

Well have the command line/ini option as well then to overide.  That way, if 
someone wants the "image aspect ratio" to be an important part of their 
scene, they can set it in the camera block.  If not, they just leave it out.

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scott <sco### [at] spamcoom> wrote:
> Well have the command line/ini option as well then to overide.  That way, if 
> someone wants the "image aspect ratio" to be an important part of their 
> scene, they can set it in the camera block.  If not, they just leave it out.

  The problem with such a thing as automatic aspect ratio (IOW the
resolution of the image to be rendered affects the camera settings)
is that it breaks the boundary between the frontend and backend engines.
It is not guaranteed that a future version of POV-Ray, where the barrier
between these two things might be very pronounced (due to things like
distributed rendering), can support that.

-- 
                                                          - Warp

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>> Well have the command line/ini option as well then to overide.  That
>> way, if someone wants the "image aspect ratio" to be an important
>> part of their scene, they can set it in the camera block.  If not,
>> they just leave it out.
>
>  The problem with such a thing as automatic aspect ratio (IOW the
> resolution of the image to be rendered affects the camera settings)
> is that it breaks the boundary between the frontend and backend
> engines. It is not guaranteed that a future version of POV-Ray, where
> the barrier between these two things might be very pronounced (due to
> things like distributed rendering), can support that.

Oh ok, so what you are saying is that in future, the frontend may not be 
able to change (or affect) any camera settings?  What about the resolution 
to be rendered, would the frontend still be capable of telling the backend 
this with the "pronounced barrier"?  If so, then I don't see why the backend 
wouldn't be capable of working out the aspect ratio and adjusting the 
camera.

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scott <sco### [at] spamcoom> wrote:
> Oh ok, so what you are saying is that in future, the frontend may not be 
> able to change (or affect) any camera settings?

  That is a possibility. (It might never realize itself, but it is a
possibility.)

>  What about the resolution 
> to be rendered, would the frontend still be capable of telling the backend 
> this with the "pronounced barrier"?

  That is exactly the info that might not be reliable/available in the
scene file in esoteric environments. (IOW even if the resolution was
available, making the scene depend on it *might* break the resulting
image.)

-- 
                                                          - Warp

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FYI - those with PS3 may want to try Super C
to sequence frames to a MPEG4 - full size 1920x1080
play back fairly quick.  put that cell processor to work.

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