POV-Ray : Newsgroups : povray.documentation.inbuilt : github #304. Inconsistent camera documentation given camera right vec 1.33 default. Server Time: 18 Jan 2019 00:59:37 GMT
  github #304. Inconsistent camera documentation given camera right vec 1.33 default. (Message 1 to 3 of 3)  
From: William F Pokorny
Subject: github #304. Inconsistent camera documentation given camera right vec 1.33 default.
Date: 6 Jul 2017 16:31:16
Message: <595e65d4$1@news.povray.org>
Please see github issue:

https://github.com/POV-Ray/povray/issues/304

Poster has a point about the documentation inconsistency I think.

Anyone know why the right vector perspective camera default is set to a 
hard coded 1.33 and not 4.0/3.0? Compatibility with old TV standards or 
something?

Bill P.


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From: clipka
Subject: Re: github #304. Inconsistent camera documentation given camera right vec1.33 default.
Date: 6 Jul 2017 18:55:21
Message: <595e8799$1@news.povray.org>
Am 06.07.2017 um 18:31 schrieb William F Pokorny:

> Anyone know why the right vector perspective camera default is set to a
> hard coded 1.33 and not 4.0/3.0? Compatibility with old TV standards or
> something?

My guess is that it simply was deemed precise enough back in the Amiga
days (320/1.33 = 240 plus change).

The quest for backward compatibility presumably did the rest.


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From: William F Pokorny
Subject: Re: github #304. Inconsistent camera documentation given camera rightvec1.33 default.
Date: 6 Jul 2017 19:36:32
Message: <595e9140$1@news.povray.org>
On 07/06/2017 02:55 PM, clipka wrote:
> Am 06.07.2017 um 18:31 schrieb William F Pokorny:
> 
>> Anyone know why the right vector perspective camera default is set to a
>> hard coded 1.33 and not 4.0/3.0? Compatibility with old TV standards or
>> something?
> 
> My guess is that it simply was deemed precise enough back in the Amiga
> days (320/1.33 = 240 plus change).
> 
> The quest for backward compatibility presumably did the rest.
> 
Thanks. The github user who recently noticed this, ubuntuslave, posted a 
link to the following newsgroup thread:

http://news.povray.org/povray.beta-test/thread/%3C3BCD6BC0.48ED3CCC@gmx.de%3E/

from 2001. I agree with Warp's post in that old thread recommending a 
change to 4.0/3.0 as the default. Any potential compatibility with past 
scenes can be addressed by hard coding a right vector to the current 
default value of 1.33.

The documentation update would then be making the default ratio 4/3 
everywhere.

Today there is a mix of defaults listed. Where all the camera defaults 
listed 1.33 is used. Below when talking about Up and Right vectors the 
default is specified as 4/3. In the Aspect ratio section it is 
right<1.33,0,0> but then claims a resulting aspect ratio of "4 to 3." 
when it is really 3.99 to 3.

Bill P.


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