scott wrote:
> Assuming the scene file author has specifically written in the camera 
> block that the aspect ratio should not be changed, then POV should give 
> the person starting the render the choice of what to do from your choice 
> - and an additional choice of changing the actual image resolution to 
> match the aspect ratio fixed in the scene file.

First, POV is highly automated.  That is, it is perfectly possible to 
start a render, walk away, and get the finished result.  Interrupting 
this process to ask a question would be a change in style (not 
necessarily bad, just needs to be pointed out).

As far as "specifically [writing] in the camera block" goes, scene 
authors already do that.  They use the "up" and "right" vectors, as well 
as the "angle" keyword, to define very specific viewports into their scenes.

Omitting these parameters is not the same as saying you don't care; it 
is still saying that you want a very specific set of parameters, just 
that these parameters happen to be the default ones.

-- 
Chambers

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> with the algorithm requiring that the top edge of the shot is still below 
> the
> horizon.

In that case it seems ok to require that the author add some command in the 
camera block fixing or limiting the aspect ratio (or in this case the 
vertical FOV).  For the default behaviour though...

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> It is unnecessary.  If you just want to put the image on your desktop, all 
> you have to do is right-click, and choose "Use as desktop."  Problem 
> solved, POV isn't even necessary.

You're right, rescaling existing images has nothing to with POV.  Shall we 
get back to rendering with POV now?

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> First, POV is highly automated.  That is, it is perfectly possible to 
> start a render, walk away, and get the finished result.  Interrupting this 
> process to ask a question would be a change in style (not necessarily bad, 
> just needs to be pointed out).

Yes, I hadn't thought about that, if a scene takes a long time to parse and 
the camera block is defined right at the end, then it could be a long time 
before POV realises there is a mismatch.  Perhaps it could be one of those 
"10 seconds to decide then I'll do it for you" boxes? IDK what the ideal 
solution would be, maybe some global setting if this seems to be a personal 
preference?

> As far as "specifically [writing] in the camera block" goes, scene authors 
> already do that.  They use the "up" and "right" vectors, as well as the 
> "angle" keyword, to define very specific viewports into their scenes.
>
> Omitting these parameters is not the same as saying you don't care; it is 
> still saying that you want a very specific set of parameters, just that 
> these parameters happen to be the default ones.

Sure, but any defaults (not just inside camera) should be based on what most 
people use most of the time, so that logically most people can avoid having 
to write those statements too often.

The discussion should be about what is the most common requirement from 
scene authors and scene renderers on the camera in terms of aspect ratio. 
IMO it is *not* the most common requirement that an image is rendered with 
non-square pixels, so it seems silly to have this as the default behaviour. 
That's all.

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Chambers <Ben### [at] gmailcom_no_underscores> wrote:
> > How do you work out what to type in for +w and +h to start with?  YOu
> > need to go and find the correct camera block for the render, which is
> > often not trivial for complex scenes due to multiple cameras being
> > defined in different files.  Then you need to wait for the render, and
> > start up a separate image editing program.  Is all that really necessary
> > when you just want to put the image on your desktop?  It certainly seems
> > unnecessary to me.
>
> It is unnecessary.  If you just want to put the image on your desktop,
> all you have to do is right-click, and choose "Use as desktop."  Problem
> solved, POV isn't even necessary.

Yeah, sure - you don't even need to render the POV-Ray scene. Rrrrright...

Pray tell, did you really *think* about the post you were answering to??

Sorry Chambers, just picking you from several who seem to have stopped (or never
even started) discussing constructively about the aspect ratio / resolution
issue, and just seem to stubbornly try to defend their position in the argument
(or is it just contradiction? I feel like giving some "being hit on the head"
lessons :P), possibly even to the extent that they deliberately misunderstand
posts, so they don't have to give in to its point.

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Chambers <Ben### [at] gmailcom_no_underscores> wrote:
> Omitting these parameters is not the same as saying you don't care; it
> is still saying that you want a very specific set of parameters, just
> that these parameters happen to be the default ones.

That's wrong.

Because it *may* indeed be saying that you want the default values - yet it
*may* also be saying that you *really* don't care. Nobody can tell. Neither
POV-Ray, nor a casual user browsing the scene code.

At any rate, from all statements you can possibly make, not specifying
parameters explicity is the very closest you can come to stating that you don't
care.

So if a scene author *definitely* wants (or even just suggests) a certain value
that *happens* to be the default, then he'd better explicitly specify that
value. If only to indicate his choice to someone reading the code.

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Alright, let's get back to the issue then.

Scenes are explicitly designed by these people called "scene designers." 
  They make their scenes to look a certain way.

If someone comes along and changes the aspect ratio, then the image no 
longer matches what the "scene designer" explicitly created.  You either 
have to show sections that weren't intended to be shown, or cut off 
sections that WERE intended to be shown.  In either case, your results 
are very likely going to be worse than the original, not to mention a 
piss in the face of said "scene designer."

I have yet to see one good argument refuting the above in this entire 
thread; most of it seems to be, "Scene designers don't REALLY mean to 
use the aspect ratio they use, they just kind of do it by accident, so 
let's go ahead and change it!" which seems both uninformed and 
disrespectful to me.

-- 
Chambers

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Chambers <Ben### [at] gmailcom_no_underscores> wrote:
> I have yet to see one good argument refuting the above in this entire 
> thread; most of it seems to be, "Scene designers don't REALLY mean to 
> use the aspect ratio they use, they just kind of do it by accident, so 
> let's go ahead and change it!" which seems both uninformed and 
> disrespectful to me.

  Hey, if 2.4:1 movies are being clipped to fit inside a 4:3 screen,
regardless of what is left out, then we can certainly do that to someone's
povray image, don't we? ;)

-- 
                                                          - Warp

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Chambers <Ben### [at] gmailcom_no_underscores> wrote:
> Alright, let's get back to the issue then.
>
> Scenes are explicitly designed by these people called "scene designers."
>   They make their scenes to look a certain way.

I do *not* think that this is "the issue".

I rather think that "the issue" is that

(a) Yes, there are scene designers that pick their scenes' aspect ratio with
care (I do, for instance);

(b) However, there are also scene designers that don't, and

(c) There are "end users" (i.e. people taking other peoples' scenes and
rendering them) who for some reason find the scene designer's decision (or
non-decision) questionable (if only because the original aspect ratio doesn't
happen to fit their desktop background image size).

The question to be solved here, in my more-or-less-humble but strong opinion, is
*not* the political one who is right in this issue and who is wrong, but the
*technical* question of how to do *all* parties justice.

I think the relevant ingredients have been mentioned already: Give the scene
author a way to *explicitly* express how he intends the scene to be rendered
regarding aspect ratio; give the "end user" a way to *explicitly* express *his*
intentions about this; and devise rules to consolidate the one with the other.

If the scene author fails to express his intentions, ignore them by default
(because how could they be respected if they are not known?); if he does
express them, respect them by default. If the end user disrespectfully requests
to override them, do so.


As for the political side: If an artist - such as a book author - publishes a
work, he loses all rights what *individuals* for their *own private* purposes
do with the work. They can tear off the cover, bury it alive, have their dog
dig it up again, burn it, pee on the ashes - whatever they like, with all due
disrespect. So why should there be any protection for POV-Ray scenes if an "end
user" *explicitly* requests to ignore the scene author's intentions?

He *may* have a valid reason to do so. That's the only thing that counts for me
as a software developer: Make things possible.

BTW, the "end user" *may* even *be* the scene author. Would you want to stop
*him* from overriding his *own* proposals?


Your argument relies on the assumption that *all* scene designers put thought
into the aspect ratio issue, and that *all* reasons an "end user" may have to
try and override the author's suggestion are disrespectful in nature.

My argument is that this assumption is wrong not because the contrary would be
true, but because your argument is categorical. Reality isn't all black and
white.


So given that software technology provides us with a means to (a) have the
author explicitly state his wishes, (b) have these wishes respected by default,
and (c) have these wishes overridden by the "end user" if he explicitly desires
to do so - why argue about it? Let's just implement all these options. Let the
author decide whether he enforces a certain aspect ratio or not, and let the
"end user" decide whether he pisses in the author's face or not.


Again, let me restate this: The "end user" may have a valid reason - which is
sufficient to invalidate your argument. Or he may not - which doesn't hurt
mine.

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> If someone comes along and changes the aspect ratio, then the image no 
> longer matches what the "scene designer" explicitly created.  You either 
> have to show sections that weren't intended to be shown, or cut off 
> sections that WERE intended to be shown.  In either case, your results are 
> very likely going to be worse than the original, not to mention a piss in 
> the face of said "scene designer."

Are you also campaigning in photoshop newsgroups to get the crop feature 
removed? :-)

Seriously, anyone can do whatever they want to scene files and images once 
the author decides to "go public" with them, you're not going to stop that 
by trying to prevent certain features being added to POV.

It was merely a suggestion because I know a lot of people go through the 
needlessly painful process of trying to get a desktop-sized render from a 
scene file.

And what about the common situation when the scene file author and the 
renderer are the same person?  I want to be able to select 1920x1200, 
1600x1200, 1680x1050, 240x320, whatever and my image to render full-screen 
with square pixels as the *default* behaviour without needing some special 
code to set this.  By not writing any special code I think I am saying "I 
don't care about aspect ratio in my scene", but POV interprets this as "I 
will fix your aspect ratio for you and give you rectangular pixels" which is 
totally backwards.

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