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31 Jul 2024 06:12:32 EDT (-0400)
  Rain problem (Message 1 to 10 of 10)  
From: JS
Subject: Rain problem
Date: 9 Oct 2007 18:05:00
Message: <web.470bfadf30614f68b46d05ed0@news.povray.org>
Hi.

At the moment I'm working on a scene where there's rain but can't work out a
way to get it done right without the scene taking forever to render. Using a
loop takes to long to place a drop of rain everywhere, and modifying the
camera texture to overlay rain is close but doesn't look quite right since
I want the rain drops everywhere (i.e. behind and in front of objects).

Also, what is the right way to do wet skin for my mannequins? The simple way
is to layer a transparent and reflective texture over the skin texture but
if there was a better way, I'd like to hear it please. Some of the skin
textures have patterns which can't be layered with the non-patterned water
texture, so that's another proble.

Thanks for your help.

You know you've been raytracing too long...when you go to change the real
world's texture and realize you can't.


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From: Bryan Valencia
Subject: Re: Rain problem
Date: 9 Oct 2007 19:00:26
Message: <470c080a$1@news.povray.org>
In general you would want to use media, not individual raindrop objects.

Look here for inspiration on an easier way though.

http://www.dangermouse.net/povray/thecity/

-- 
---
Bryan Valencia

- I'd rather live with false hope than with false despair.


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From: Alain
Subject: Re: Rain problem
Date: 9 Oct 2007 20:15:25
Message: <470c199d$1@news.povray.org>
JS nous apporta ses lumieres en ce 2007/10/09 18:04:
> Hi.
> 
> At the moment I'm working on a scene where there's rain but can't work out a
> way to get it done right without the scene taking forever to render. Using a
> loop takes to long to place a drop of rain everywhere, and modifying the
> camera texture to overlay rain is close but doesn't look quite right since
> I want the rain drops everywhere (i.e. behind and in front of objects).
The camera normal trick is good to simulate drops sticking on the camera's 
objective, not for the overall rain. You can use that in conjunction with other 
techniques.
> 
> Also, what is the right way to do wet skin for my mannequins? The simple way
> is to layer a transparent and reflective texture over the skin texture but
> if there was a better way, I'd like to hear it please. Some of the skin
> textures have patterns which can't be layered with the non-patterned water
> texture, so that's another problem.
You may add some finish to the whole texture:
texture{Objects_Texture finish {specular 0.2 roughness 0.1}}
This will override any specular that may be present it that texture.
You can replace specular and roughness with phong and phong_size if you prefer.

Do you have access to those texture? If so, try to edit it's finish or add some 
layer.
> 
> Thanks for your help.
> 
> You know you've been raytracing too long...when you go to change the real
> world's texture and realize you can't.
> 
> 
> 
Only use individual drops for those close enough to the camera to actualy be 
distinctly seen, probably less than 100.
For the rest, using some media and fog is the favored way. For example, you can 
use a crackle pattern with a density_map that is mostly zero and that spikes to 
a large value over a small range of values. Optionaly stretch it to simulate 
motion bluring of the drops. Place that media in a container to prevent it to 
ocupy the space beyhond where you can actualy see the specks it provide, gaining 
speed.
For the rest, use fog, unless you need your rain to interact with your light.

-- 
Alain
-------------------------------------------------
f u cn rd ths, u cn gt a gd jb n cmptr prgrmmng.


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From: JS
Subject: Re: Rain problem
Date: 9 Oct 2007 20:40:01
Message: <web.470c1e8d53d001e7b46d05ed0@news.povray.org>
Hi.

Thanks for your help, I will try out those ideas. However, I can't just edit
the textures even though they're my own because I won't always need wet
effects. That is, the textures need to be 'normal' in a dry scene and wet
for another.

James S.


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From: Rune
Subject: Re: Rain problem
Date: 10 Oct 2007 07:29:54
Message: <470cb7b2$1@news.povray.org>
"JS" wrote:
> At the moment I'm working on a scene where there's rain but can't work out 
> a
> way to get it done right without the scene taking forever to render. Using 
> a
> loop takes to long to place a drop of rain everywhere

Perhaps have a look at my post "Flying though space" in 
povray.binaries.images.

Though the effect was made with particles in space in mind, it should work 
well for rain drops too. What is does is to create particles only in the 
area around the camera. This would probably work well to create all the 
visible rain drops. You can then combine it with media as the others here 
have mentioned (or other tricks) to also simulate the overall rainy 
atmosphere at long distance.

By the way - note that Gilles Tran's famous rainy city image "The Wet Bird" 
was made without having any rain drops in the scene at all - it's all made 
with wet looking textures combined with the right atmosphere.

Rune


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From: Thomas de Groot
Subject: Re: Rain problem
Date: 10 Oct 2007 07:45:30
Message: <470cbb5a$1@news.povray.org>
Look also at this, from Jaime Vives Piqueres:
http://www.ignorancia.org:80/uploads/images/raining/wips/townstreet-night-070102-2.jpg

Unfortunately, I believe, he lost the code for this, as stated in the thread 
"lost rain" in p.b.i. (april 19th, 2007)
However he said there that
<quote>
The rain is just
cylinders and tori with tricky textures and repeated randomly. The
splashes are traced against the objects in the scene for placement.
<unquote>

Thomas


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From: Alain
Subject: Re: Rain problem
Date: 10 Oct 2007 11:26:42
Message: <470cef32$1@news.povray.org>
JS nous apporta ses lumieres en ce 2007/10/09 20:36:
> Hi.
> 
> Thanks for your help, I will try out those ideas. However, I can't just edit
> the textures even though they're my own because I won't always need wet
> effects. That is, the textures need to be 'normal' in a dry scene and wet
> for another.
> 
> James S.
> 
> 
In that case, you can edit the original textures and rename them as texture_Wet, 
keeping the original intact.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you spend $2000 on upgrading your 
computer so that POV-Ray runs faster, and you scoff at Rhino for costing so much.


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From: Jaime Vives Piqueres
Subject: Re: Rain problem
Date: 10 Oct 2007 17:37:10
Message: <470d4606$1@news.povray.org>
Thomas de Groot wrote:
> Look also at this, from Jaime Vives Piqueres:
>
http://www.ignorancia.org:80/uploads/images/raining/wips/townstreet-night-070102-2.jpg
> 
> Unfortunately, I believe, he lost the code for this, 

   Yes, but I've almost finished rewriting it. I'm just waiting to have the 
time to clean and comment it, as with many other projects... :(

   Indeed, JS, for the rain drops in the air I just used cylinders with a 
vertical gradient texture: exactly 100000 cylinders (not counting the 
streaks and other splashes). I didn't find it that slow, but I've a fast 
machine...

--
Jaime


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From: Thomas de Groot
Subject: Re: Rain problem
Date: 11 Oct 2007 03:09:38
Message: <470dcc32@news.povray.org>
"Jaime Vives Piqueres" <jai### [at] ignoranciaorg> schreef in bericht 
news:470d4606$1@news.povray.org...
>
>   Yes, but I've almost finished rewriting it. I'm just waiting to have the 
> time to clean and comment it, as with many other projects... :(
>

Oh! That's good Jaime!

Thomas


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From: Christian Froeschlin
Subject: Re: Rain problem
Date: 11 Oct 2007 14:09:31
Message: <470e66db$1@news.povray.org>
Jaime Vives Piqueres wrote:

>   Indeed, JS, for the rain drops in the air I just used cylinders with a 
> vertical gradient texture: exactly 100000 cylinders (not counting the 
> streaks and other splashes).

A blob object might also be suitable for this
and it should render considerably faster.


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