Let me explain my situation first, OK ?

I don't know much about raytracing, and I feel like I 'll always be a
beginner, but I do admire some of the art that you can create with it.
For years I have dreamt of rendering those images at very high
resolution, have a photographer print them and then put them in a frame
on my wall.
And I don't mean to see this as a commercial thing.

So more than ten years later, technology has evolved, and local
photographers now allow you to send a JPG file to them, so that they can
print it at say, 20x30cm.

This is where the trouble starts.
Classical photography uses a 3:2 aspect ratio, whereas most images I can
find come in the 4:3 aspect ratio format, which you need for a full
screen picture.

Some of the scenes (like PACMAN.POV) can easily be changed by changing
the UP and RIGHT lines, sometimes you can add those lines to produce the
format you need.

But when I take a look at the IRTC, in many cases other camera types are
used, and I am unable to render them at another aspect ratio.

This, for instance is the camera part from CHAINREA.POV.
Could anyone tell me how I could recalculate this image to make it a
different aspect ratio (for example 16:9).
I choose 16:9, because then you can easily see if the image gets
deformed (rerender at 800x450, for example).

camera
{
 location  <30.0 , 24.0 , 24.0>
 look_at   <0.0 , 1.5 , 0.0>
 angle 25
 focal_point <0.0, 1.5, 0.0>
 aperture 0.4
 blur_samples 4
}

Any idea how I could change this camera so I get a 16:9 image or a 3:2
image ?
It 's just an example, but if there is a mathematical method I can use,
I could apply it to the other images as well.
I have already rerendered the Old Cinema image at 3000x2000 (aspect
ratio 3:2) and it looks very pretty.
I think other images would look great as well.

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Just look in the pov-docu:

Up and Right Vectors
The primary purpose of the up and right vectors is to tell POV-Ray the relative
height and width of the view screen. The default values are:

 right 4/3*x
 up y

So just change them to the values you like.

Christoph

--
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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On Wed, 23 Aug 2000 21:30:28 +0200, Filiep Geeraert wrote:
>This, for instance is the camera part from CHAINREA.POV.
>Could anyone tell me how I could recalculate this image to make it a
>different aspect ratio (for example 16:9).

You may have trouble with this image; it was rendered with a custom,
unreleased version of POV-Ray.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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Thanks, Christoph.
With this information I was able to rerender it at 16:9.
I always test it with this aspect ratio, because you can more easily
tell if the image has been skewed.
This is the camera part, how I changed it for a 16:9 image.
Now the image at 800x450 looks correct.
Hope this will do the trick for some other images as well.
Some of them are really nice.


camera
{
  location  <30.0 , 24.0 , 24.0>
  right 16/9*x
  up y
  look_at   <0.0 , 1.5 , 0.0>
  angle 25
  focal_point <0.0, 1.5, 0.0>
  aperture 0.4
  blur_samples 4
}

Christoph Hormann wrote:
> 
> Just look in the pov-docu:
> 
> Up and Right Vectors
> The primary purpose of the up and right vectors is to tell POV-Ray the relative
> height and width of the view screen. The default values are:
> 
>  right 4/3*x
>  up y
> 
> So just change them to the values you like.
> 
> Christoph
> 
> --
> Christoph Hormann <chr### [at] gmxde>
> Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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The camera below and some editing of your quickres.ini file should solve
your problem.

#declare A=2.5;    // viewing angle
camera{
  //orthographic // for orthographic mode
  location  <50,50,50>
  sky       y
  direction y
  right     y*A
  up        (image_height/image_width)*A*y
  angle     A
  look_at   <0,0,0>
}

The up value is defined by the height and width of the image declared in
your Quickres.ini file(tools/Edit secondary INI file), so at whatever size
you specify to render the aspect ratio should be preset.  Now, in order to
render, say, a 300x200 image, just enter the following code in your
Quickres.

[300x200 AA 0.3]
Width=300
Height=200
Antialias=On
Antialias_Threshold=0.3

That should so it.

-Chris-

Filiep Geeraert <fil### [at] poboxescom> wrote in message
news:39A42654.E51F643E@poboxes.com...
> Any idea how I could change this camera so I get a 16:9 image or a 3:2
> image ?
> It 's just an example, but if there is a mathematical method I can use,
> I could apply it to the other images as well.
> I have already rerendered the Old Cinema image at 3000x2000 (aspect
> ratio 3:2) and it looks very pretty.
> I think other images would look great as well.

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You 're right, although it renders, the image is different from the one
entered into the competition.
There is no motion blur on the balls.
Seems like the author wrote a program to create 40 different frames and
then combine them into one.
Another file that I can't rerender : (
It 's a pity that so many files seem to give problems when you try to
rerender them.
Either the author has left out some vital include files or image maps or
it was created with a very special version of Povray.


Ron Parker wrote:
> 
> On Wed, 23 Aug 2000 21:30:28 +0200, Filiep Geeraert wrote:
> >This, for instance is the camera part from CHAINREA.POV.
> >Could anyone tell me how I could recalculate this image to make it a
> >different aspect ratio (for example 16:9).
> 
> You may have trouble with this image; it was rendered with a custom,
> unreleased version of POV-Ray.
> 
> --
> Ron Parker   http://www2.fwi.com/~parkerr/traces.html
> My opinions.  Mine.  Not anyone else's.

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For this image it doesn't seem to work (the Copperfish) :

camera {  //  Camera Camera01
  location  <21.254, -60.354, 5.000>
  direction <0.0,     0.0,  2.4880>
  sky       <0.0,     0.0,  1.0>  // Use right handed-system!
  up        <0.0,     0.0,  1.0>  // Where Z is up
  right     <1.33333333,  0.0,  0.0>
  look_at   <0.000, 0.000, 0.000>
}

Why is it that if I change the 1.333333333 to 1.5 and render at 600x400
(aspect ratio 3:2) the whole scene gets deformed ?
Isn't this the same as some of those other drawings ?

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Assuming square pixels, aspect ratio for any image size
can be specified entirely in the "right" command in the camera
object (as long as you keep the "up" command at value of one).

 ... for example ...

#declare horizontal_aspect = 16;
#declare vertical_aspect = 9;

camera {
  location <0, 0, 0>
  direction <0, 0, 1>  // off-topic note: increase this to "zoom" in
  right <horizontal_aspect / vertical_aspect, 0, 0>
  up <0, 1, 0>
  // put look_at or rotate & translate statements here
}


        You can always just use the size of the image, as
in ....

  right <640 / 480 , 0, 0>
  up <0, 1, 0>

        Also: I find it easier to use the output image dimensions
for the horizontal_aspect and vertical_aspect values.  Since we
are dealing with a ratio, we can choose our units of measurement
arbitrarily.
        For example, one time I was rendering an image at to be
printed on an 11" x 8.5" peice of paper.  With margins, that ended
up as an image size of 10.5" x 8".  So:

  right <10.5 / 8, 0, 0>


        For non-square pixels (as in an Amiga at an ntsc display
mode), simply multiply by the actual aspect of a pixel.  Since
an Amiga ntsc pixel is 10:11, do this for a 640 x 400 image:

  right <(640 / 400) * (10/11), 0, 0>

        took me YEARS to figure that last bit out.

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