scott wrote:
> I can't even remember the number of times I have had to search 
> through and put in some "image_width/image_height" statement.

Then you're abusing other peoples' images.  Maybe you should accept the 
fact that particular images are not going to fit your monitor 
full-screen, but will instead have to be either cropped or letterboxed.

 From what you've been saying, it sounds like you'd prefer cropping.

Anyway, I firmly believe that input should be separate from output, and 
that any image should be renderable at any resolution.

-- 
Chambers

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>> Of course not, but using eg "hfov" instead of "angle" means you don't 
>> even
>> need to open the documentation to realise what it is setting.
>
>  And exactly how would you even know about the "hfov" keyword without
> reading the documentation?

Because it comes in the default camera block? (Insert -> Camera -> ...) or 
has been already written in a scene you are looking at?  The benefit then is 
that you can be pretty sure what it means straight away without needing to 
look it up in the documentation.  That's why we use meaningful keywords, so 
you don't have to look up everything.  Otherwise we could just use random 
sequences of letters!

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>  If the author didn't put such a statement in their camera block, then
> maybe the author didn't even intend for the image to be rendered in other
> aspect ratios?

Or maybe they just used the default, couldn't be bothered, or didn't even 
realise?  I still think if you want to enforce some fixed aspect ratio you 
should have to add it specifically, as it is not the usual behaviour needed 
when rendering.

>  And if you really want to censor part of the image so that it will fit
> your screen, then how about rendering it with the intended aspect ratio
> and the width of your screen, and then clip it with image editing 
> software?

So what, I have to search for the correct camera block, figure out what 
aspect ratio is used, compare it to my monitor aspect ratio, work out the 
dimensions so that it will fill my monitor (either width of height is the 
same, the other dimension is calculated), render the image, then load it 
into an image program and crop it to exactly the monitor dimensions?  Sure 
it's possible, but a sensible default behaviour would make it easier...

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scott <sco### [at] scottcom> wrote:
> Sure 
> it's possible, but a sensible default behaviour would make it easier...

  And what, in your opinion, should the "sensible default behavior" be
if the author wanted, for example, for his image to be rendered in a very
widescreen format like, let's say, 2.4:1 (typical movie aspect ratio), and
this because he composed his image so that it will work the best with that
aspect ratio?

  I somehow get the feeling that you are making the assumption that all
scenes are designed for a 4:3 aspect ratio because that's the default,
and that you are arguing what happens when you want to render it for a
16:9 (or sometimes 16:10) monitor.

  However, often when an author uses a very different aspect ratio, eg.
a very widescreen one, or perhaps the other extreme, a square one (or
even one which is taller than wide, for artistic composition purposes)
it's because he really intends for the image to be rendered with that
aspect ratio. Imagine that someone composes a scene which has an aspect
ratio of 1:2 (twice as tall as wide), eg. for a postcard. He *definitely*
composed the scene for that precise aspect ratio, not anything else.

  So what would be, in your opinion, the "sensible default behavior"
when you then try to render that 1:2 image into a 16:9 one? Maybe render
a 16:9 part in the middle of the original 1:2 image?

  I'm sorry, but I just disagree with you. The original image composition
should be preferred over anything else, unless the author *specifically*
allows other aspect ratios to be used (which he can in the current POV-Ray).

-- 
                                                          - Warp

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scott <sco### [at] scottcom> wrote:
> >  And exactly how would you even know about the "hfov" keyword without
> > reading the documentation?

> Because it comes in the default camera block? (Insert -> Camera -> ...)

  You assume everyone uses winpov, and the insert menu?

> or has been already written in a scene you are looking at?

  So you are simply delegating reading the documentation to someone else?
And how's that different from someone else having read the documentation
about the 'angle' keyword and explaining it to you?

-- 
                                                          - Warp

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>  I somehow get the feeling that you are making the assumption that all
> scenes are designed for a 4:3 aspect ratio because that's the default,
> and that you are arguing what happens when you want to render it for a
> 16:9 (or sometimes 16:10) monitor.

Yes, that is my assumption for the default behaviour, that the author just 
uses the default aspect ratio without a second thought for anyone else who 
might want to render it.  This is quite typical of the images you see posted 
on this server, which often then people then want to render as a desktop 
wallpaper.

>  However, often when an author uses a very different aspect ratio, eg.
> a very widescreen one, or perhaps the other extreme, a square one (or
> even one which is taller than wide, for artistic composition purposes)
> it's because he really intends for the image to be rendered with that
> aspect ratio.

Sure, and in that case the author should have to force the aspect ratio in 
his scene file - but it shouldn't be the default behaviour.

>  I'm sorry, but I just disagree with you. The original image composition
> should be preferred over anything else, unless the author *specifically*
> allows other aspect ratios to be used (which he can in the current 
> POV-Ray).

I see what you're saying, but my point is that in most cases (just look at 
the last 20 or images from p.b.i) the author has not set any specifc aspect 
ratio or any particular scene geometry that wouldn't work with a different 
aspect ratio.  I see it that your example is the exception to the norm, the 
author chooses some carefully calculated aspect ratio and designs his scene 
specifically only to work with that exact aspect ratio.  In which case I see 
that as a silly choice for the default behaviour.

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>> Because it comes in the default camera block? (Insert -> Camera -> ...)
>
>  You assume everyone uses winpov, and the insert menu?

No, but it's a jolly useful time saver, I recommend it.

>> or has been already written in a scene you are looking at?
>
>  So you are simply delegating reading the documentation to someone else?

That is a silly argument, the "someone else" would need to read the 
documentation anyway, so what's the disadvantage of using more meaningful 
keywords.  No wonder POV is so slow to develop if you have to debate whether 
using more meaningful keywords is a good thing or not :-(  Oh well.

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I think that there's a fundamental problem that a 4:3 aspect ratio is built-in
to the current camera.  It's not just about taking other's code and abusing it
(albeit how many really *want* to wreck non 4:3 viewing). It's not about trying
to make something full screen-- there is the concept of making one's own "art"
for print with povray, and I've got one non-4:3 monitor anyway. And what about
making square avatars?!

Stepping back a moment, there is a problem with the docs, notably the diagram,
in that the aspect ratio is NOT part of the visual equation the reader is
invited to make.  The docs have all the truth in them, in that anyone who
complains can be pointed to a phrase where they didn't RTFM, but the doesn't
*teach*. The diagram also doesn't sufficiently tell the relation between angle
and distance. If you already know how it works, the diagram doesn't lie, but it
doesn't tell you how povray uses them or handles the hierarchy of the
potentially redundant variables.


Scott sums up my views with:

<< The current default behaviour means that if you want to render someone elses
scene for your desktop wallpaper or to print out, you have to search through
their code for the right camera block and make some changes, I can't even
remember the number of times I have had to search through and put in some
"image_width/image_height" statement.  Is this really the best thing for the
default behaviour?  IMO the default behaviour should mean the least work for
what is most common, ie if you actually *want* non-square pixels you should
have to go and fiddle with the code.>>


IMHO, the current camera object is something that a smart person *can* figure
out with some work. But with so many things in programming, eventually the
exercise in pure logic ends, and the question of "How did this person decide to
put it together?" starts.  It's not logical.

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Piling on:

How about making a one-pass anaglyph, doing image processing, or setting up a
captioning system for animation, submitting to an animation contest that wants
non-4:3 entries?  For doing "great things" in povray (as opposed to "petty
things" in povray like taking someone's code to make full-screen wallpaper),
you might have to know exactly where an object will be relative to the camera.

I submit that if you gave a bunch of intelligent people the docs, most of them
wouldn't be able to straight-up code a box that exactly fills the screen. You
could probably dig up phrases buried somewhere in the doc to embarrass them
however. That's a problem.

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scott <sco### [at] scottcom> wrote:
> In which case I see 
> that as a silly choice for the default behaviour.

  I asked what should, in your opinion, be the default behavior. You didn't
answer that question.

-- 
                                                          - Warp

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