Gilles Tran <tra### [at] inapginrafr> wrote:
> Unless it's one single colour, a squeezed/stretched image is *** always ***
> bad.

  What do you mean always?
  If I'm making a 320x400 windows startup image, I *want* the image to
still have 4:3 aspect ratio even though the resolution is not. The image
will look stretched when viewed normally, but it's exactly what I want.
  You can't say "always".

> There's zero point in rendering it, period. So, at its
> worst, the automatic trick is the lesser of two evils.

  I wouldn't be so sure that automatic aspect ratio setting is the lesser
of two evils.
  When you render with the wrong aspect ratio, you can at least clearly
*see* that there's something wrong with the image. This is specially
the case when you try to render a scene with a wider aspect ratio
in a default 4:3 resolution (some of the POV-Ray example scenes are
good examples of this): You will *see* that there's something wrong
with it.
  However, if the scenes had automatic aspect ratio correction, there's
a big chance you won't notice that you did something wrong when you
make a 4:3 render of it. You might wonder why there are some oddities
at the top and the bottom of the image (if the author didn't bother
to properly model those parts) but you would simply assume it's a
mistake of the author, not your mistake. However, you will be rendering
the image in a way the original author didn't intend.

  I personally find this specially bothering because the automatic
aspect ratio setting modifies the viewing area *vertically*, which
is the less usual image area change (usually images are made to
be viewed in widescreen, if anything). You may eg. model a landscape
which looks ok no matter where you look at it by rotating the camera
horizontally, but you don't care how the landscape looks below the
camera because it's outside the image... except if someone happens
to render the image with a different aspect ratio than you.

  So my strong opinion is that *no* automatic aspect ratio setting in
POV-Ray by default, and people should really give the "trick" with
a warning of its side-effects. (Something like "be aware that if
you render using a resolution with a different aspect ratio, the
viewing area will be modified in the vertical direction, thus giving
or removing image area from the top and bottom of the image".)

  I would like the trick more if it modified the viewing area horizontally,
but it doesn't.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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