POV-Ray : Newsgroups : povray.documentation.inbuilt : Emission Server Time: 18 Jan 2019 01:01:45 GMT
  Emission (Message 1 to 8 of 8)  
From: Mike Horvath
Subject: Emission
Date: 19 Nov 2016 18:23:13
Message: <58309891$1@news.povray.org>
Per this thread:

http://forums.ldraw.org/showthread.php?tid=21710&pid=23882&mode=threaded

The wording of the docs may not be entirely clear. Not sure what to 
replace it with, however.

Mike


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From: Jim Holsenback
Subject: Re: Emission
Date: 20 Nov 2016 12:45:04
Message: <58319ad0$1@news.povray.org>
On 11/19/2016 1:23 PM, Mike Horvath wrote:
> Per this thread:
>
> http://forums.ldraw.org/showthread.php?tid=21710&pid=23882&mode=threaded
>
> The wording of the docs may not be entirely clear. Not sure what to
> replace it with, however.


hmmm ... not sure if I'm following. With regards to emission passage all 
I'm seeing is a bit of change to the wiki/html markup. Since it was a 
/change/ in behavior at 3.7 I'd emphasize that with the wiki {{Change}} 
template at the beginning of the 1st paragraph. In the 2nd paragraph I'd 
tag the word /except/ with 'em' and it's neighboring /emission/ with 
'code' so it appears green like the other keywords


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From: Mike Horvath
Subject: Re: Emission
Date: 21 Nov 2016 15:16:50
Message: <58330fe2$1@news.povray.org>
On 11/20/2016 7:45 AM, Jim Holsenback wrote:
> On 11/19/2016 1:23 PM, Mike Horvath wrote:
>> Per this thread:
>>
>> http://forums.ldraw.org/showthread.php?tid=21710&pid=23882&mode=threaded
>>
>> The wording of the docs may not be entirely clear. Not sure what to
>> replace it with, however.
>
>
> hmmm ... not sure if I'm following. With regards to emission passage all
> I'm seeing is a bit of change to the wiki/html markup. Since it was a
> /change/ in behavior at 3.7 I'd emphasize that with the wiki {{Change}}
> template at the beginning of the 1st paragraph. In the 2nd paragraph I'd
> tag the word /except/ with 'em' and it's neighboring /emission/ with
> 'code' so it appears green like the other keywords

The docs say, "The intention is to simplify the use of materials 
designed for non-radiosity scenes in scenes with radiosity, or the 
design of scenes that can be rendered with or without radiosity."

I don't think this is the primary reason to use emission. I think that 
emission is supposed to be used for glowing objects. The wording makes 
it seem like it is just a hack to retain old behavior from POV 3.6. This 
is what threw the developer off in the thread I linked to.


Mike


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From: Jim Holsenback
Subject: Re: Emission
Date: 21 Nov 2016 17:19:09
Message: <58332c8d$1@news.povray.org>
On 11/21/2016 10:16 AM, Mike Horvath wrote:
> I don't think this is the primary reason to use emission. I think that
> emission is supposed to be used for glowing objects. The wording makes
> it seem like it is just a hack to retain old behavior from POV 3.6. This
> is what threw the developer off in the thread I linked to.

to quote myself from an earlier post in different NG ... mo betta?

http://wiki.povray.org/content/Reference:Finish#Emission


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From: clipka
Subject: Re: Emission
Date: 21 Nov 2016 18:37:44
Message: <58333ef8$1@news.povray.org>
Am 21.11.2016 um 18:19 schrieb Jim Holsenback:
> On 11/21/2016 10:16 AM, Mike Horvath wrote:
>> I don't think this is the primary reason to use emission. I think that
>> emission is supposed to be used for glowing objects. The wording makes
>> it seem like it is just a hack to retain old behavior from POV 3.6. This
>> is what threw the developer off in the thread I linked to.
> 
> to quote myself from an earlier post in different NG ... mo betta?
> 
> http://wiki.povray.org/content/Reference:Finish#Emission

Actually, no -- sorry ;)

"There has been a Change as of version 3.7 that allows you to add the
emission keyword to the finish block. One intention is to simplify the
use of materials designed for non-radiosity scenes that are in scenes
with radiosity, or the design of scenes that can be rendered with or
without radiosity. However, emission can also be used with objects that
are intended to glow."

That description implies that there would be two entirely different use
cases: one radiosity-related, and one related to glowing materials. The
truth is that they are one and the same.


Maybe something like this:

---------------------------------------------
The `emission` keyword, NEW in version 3.7, can be used to model glowing
materials, eliminating the need to co-opt `ambient` for this purpose.

The syntax and effect are virtually identical to `ambient`, except that
`emission` is unaffected by the global `ambient_light` parameter, and is
not turned off when using radiosity.
---------------------------------------------

Also, the "Ambient" section may need a bit of love and care as well; I
suggest replacing the last paragraph before the final note with
something like this:

---------------------------------------------
Ambient light affects both shadowed and non-shadowed areas, so if you
turn up the ambient value, you may want to turn down the diffuse and
reflection values.

There has been a CHANGE as of version 3.7 in that the `ambient`
mechanism is now automatically turned off when radiosity is enabled
(provided `#version` is set to 3.7 or higher), allowing you to use the
same material definitions for both radiosity and non-radiosity scenes.
As a consequence, the practice of co-opting `ambient` to model glowing
materials will no longer work in radiosity scenes and is therefore
strongly discouraged altogether; instead, the new `emission` keyword has
been added specifically for this purpose.
---------------------------------------------


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From: Mike Horvath
Subject: Re: Emission
Date: 21 Nov 2016 18:49:58
Message: <583341d6$1@news.povray.org>
On 11/21/2016 1:37 PM, clipka wrote:
> instead, the new `emission` keyword has
> been added specifically for this purpose.

"instead, the new emission keyword should be used to model glowing objects."

Mike


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From: Jim Holsenback
Subject: Re: Emission
Date: 21 Nov 2016 20:37:01
Message: <58335aed$1@news.povray.org>
On 11/21/2016 1:37 PM, clipka wrote:
> Am 21.11.2016 um 18:19 schrieb Jim Holsenback:
>> On 11/21/2016 10:16 AM, Mike Horvath wrote:
>>> I don't think this is the primary reason to use emission. I think that
>>> emission is supposed to be used for glowing objects. The wording makes
>>> it seem like it is just a hack to retain old behavior from POV 3.6. This
>>> is what threw the developer off in the thread I linked to.
>>
>> to quote myself from an earlier post in different NG ... mo betta?
>>
>> http://wiki.povray.org/content/Reference:Finish#Emission
>
> Actually, no -- sorry ;)

it's been fixed bwana ... along with several run-on sentences and bad 
grammar etc ... looked at the entire page


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From: Mike Horvath
Subject: Re: Emission
Date: 21 Nov 2016 21:05:21
Message: <58336191$1@news.povray.org>
On 11/21/2016 3:36 PM, Jim Holsenback wrote:
> On 11/21/2016 1:37 PM, clipka wrote:
>> Am 21.11.2016 um 18:19 schrieb Jim Holsenback:
>>> On 11/21/2016 10:16 AM, Mike Horvath wrote:
>>>> I don't think this is the primary reason to use emission. I think that
>>>> emission is supposed to be used for glowing objects. The wording makes
>>>> it seem like it is just a hack to retain old behavior from POV 3.6.
>>>> This
>>>> is what threw the developer off in the thread I linked to.
>>>
>>> to quote myself from an earlier post in different NG ... mo betta?
>>>
>>> http://wiki.povray.org/content/Reference:Finish#Emission
>>
>> Actually, no -- sorry ;)
>
> it's been fixed bwana ... along with several run-on sentences and bad
> grammar etc ... looked at the entire page
>

That is better but may be too terse.

Mike


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