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From: Sven Littkowski
Subject: Transparent PNGs
Date: 9 Oct 2017 10:56:16
Message: <59db55d0$1@news.povray.org>
Hi

is it possible to create a scene where the rendered items are visible
but the entire empty background becomes transparent, if the output image
is a PNG?

---
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From: Stephen
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 11:33:29
Message: <59db5e89$1@news.povray.org>
On 09/10/2017 11:56, Sven Littkowski wrote:
> Hi
> 
> is it possible to create a scene where the rendered items are visible
> but the entire empty background becomes transparent, if the output image
> is a PNG?
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 

Set Alpha output to on. And IIRC the background should be black.


http://www.povray.org/documentation/view/3.6.0/219/


-- 

Regards
     Stephen


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From: Thomas de Groot
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 11:38:04
Message: <59db5f9c$1@news.povray.org>
On 9-10-2017 12:56, Sven Littkowski wrote:
> Hi
> 
> is it possible to create a scene where the rendered items are visible
> but the entire empty background becomes transparent, if the output image
> is a PNG?

Yes. Creating a Billboard.

Rapidly, from memory, you need to comment out every object in your scene 
(including backgrounds) except the object you want rendered, and render, 
adding +ua in order to switch the alpha channel on.

As far as I remember, you may need to check the alpha channel of the png 
image in a paint application (I recommend IC for that) after you finish 
the render. It might be better to render as tga and later convert to png 
if necessary.

-- 
Thomas


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From: Bald Eagle
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 11:40:00
Message: <web.59db5fd4c5de9ff4c437ac910@news.povray.org>
Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
> Hi
>
> is it possible to create a scene where the rendered items are visible
> but the entire empty background becomes transparent, if the output image
> is a PNG?

Of course.  This question has been asked loads of times, probably even by
myself.

TdG recommends:
background { colour srgbt <0.0, 0.0, 0.0, 1.0> }

http://news.povray.org/povray.newusers/thread/%3Cweb.58acb474275844131c311e660%40news.povray.org%3E/


Warp recommends activating alpha in the command line (+ua), and using no
background whatsoever:

http://news.povray.org/povray.newusers/thread/%3Cweb.4890c3a87699c0d4749f26950@news.povray.org%3E/?ttop=344503&toff=150


http://news.povray.org/povray.newusers/thread/%3C45033d21@news.povray.org%3E/


Whatever works for you.


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From: Bald Eagle
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 11:45:01
Message: <web.59db612ec5de9ff4c437ac910@news.povray.org>
Fine everybody just pile on at once....  :|


Here's some advice on making a composite image, if you want shadows and a
transparent background (link to .pov file too :)  )

http://news.povray.org/povray.newusers/thread/%3C45033d21@news.povray.org%3E/


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From: Lars R 
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 11:57:55
Message: <59db6443$1@news.povray.org>
Am 09.10.2017 um 12:56 schrieb Sven Littkowski:
> Hi
> 
> is it possible to create a scene where the rendered items are visible
> but the entire empty background becomes transparent, if the output image
> is a PNG?

I guess you didn't know the command line parameter +ua (or
Output_Alpha=On in the INI file), did you?

Lars R.


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From: Stephen
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 12:00:20
Message: <59db64d4$1@news.povray.org>
On 09/10/2017 12:38, Thomas de Groot wrote:
> It might be better to render as tga and later convert to png if necessary.

Is that one of those "Plant thy Mandrake when the moon is in Taurus and 
waning gibbous.", things? :-P


-- 

Regards
     Stephen


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From: clipka
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 12:41:12
Message: <59db6e68$1@news.povray.org>
Am 09.10.2017 um 13:39 schrieb Bald Eagle:

>> is it possible to create a scene where the rendered items are visible
>> but the entire empty background becomes transparent, if the output image
>> is a PNG?
> 
> Of course.  This question has been asked loads of times, probably even by
> myself.
> 
> TdG recommends:
> background { colour srgbt <0.0, 0.0, 0.0, 1.0> }

That.

> Warp recommends activating alpha in the command line (+ua), and using no
> background whatsoever:

Those posts date back to the days of v3.6. The handling of transparency
has been overhauled since then, so don't expect that advice to work in v3.7.


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From: Sven Littkowski
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 13:15:13
Message: <59db7661$1@news.povray.org>
On 09.10.2017 06:56, Sven Littkowski wrote:
> Hi
> 
> is it possible to create a scene where the rendered items are visible
> but the entire empty background becomes transparent, if the output image
> is a PNG?
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 
Biiiig thanks to everyone here! You all helped me a lot, and my problem
seems to be solved now.

No, I had indeed not know the +ua switch. Never had a need for such. But
I am reconstructing ancient Roman ships, and just their oars I want to
do in render technology. Which brings me to the next problem, how to
recreate one of the Roman-style galley oars. it is too easy just to use
a long cylinder with a flattened (thin-scaled) oval cylinder at the end.
The transition between shaft and brad area was kinda smooth.


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From: Sven Littkowski
Subject: Re: Transparent PNGs
Date: 9 Oct 2017 13:23:55
Message: <59db786b@news.povray.org>
On 09.10.2017 09:15, Sven Littkowski wrote:
> On 09.10.2017 06:56, Sven Littkowski wrote:
>> Hi
>>
>> is it possible to create a scene where the rendered items are visible
>> but the entire empty background becomes transparent, if the output image
>> is a PNG?
>>
>> ---
>> Diese E-Mail wurde von AVG auf Viren geprüft.
>> http://www.avg.com
>>
> Biiiig thanks to everyone here! You all helped me a lot, and my problem
> seems to be solved now.
> 
> No, I had indeed not know the +ua switch. Never had a need for such. But
> I am reconstructing ancient Roman ships, and just their oars I want to
> do in render technology. Which brings me to the next problem, how to
> recreate one of the Roman-style galley oars. it is too easy just to use
> a long cylinder with a flattened (thin-scaled) oval cylinder at the end.
> The transition between shaft and brad area was kinda smooth.
> 
Ships like these, in high-res. Some US book publications already showing
parts of my work in the field of maritime archaeology. But I have
something in mind about the oars, that will make them looking even more
realistic.


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