Hi, guys,

Nowadays I have rendered a scene of raindrops on a leaf surface with Pov-Ray for
windows. And now I get a rendering result which you can see as following.

Generally speacking, this result of raindrop rendering has a long distance from
the realistical appearence. You can see the raindrops on the leaf has an ugly
reflection and they are not transparent enough. However many papermeters of drop
material have been modified several times, but I can't get a satisfying result.

Therefore, here I ask for your help for how to render this scene for a
realistical result? How to set the papemeters for drops meterial?


--------------------------------------------------------------------------------
The following is my parameter setting for drop:

material {
      texture{
           pigment{Clear}
           finish{
                reflection {0.1,0.3}
                conserve_energy
                ambient 0 diffuse 0
                specular 0.8 roughness 1/1000
                  }
       }
       interior {
        ior 1.33
     }
  }

--------------------------------------------------------------------------------

Expect your answer sincerely.

Thank you.

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Attachments:
Download 'raindrops265.png' (405 KB)

Preview of image 'raindrops265.png'

Hello,

Maybe you need to simplify your material definition to very basics (just a clear
pigment) then add features back one at a time to see what's causing the strange
coloration. For example, try using transmit instead of filter (or filter instead
of transmit) then add ior, conserve_energy, etc. Also, you can add photons for
more realism.

Good luck, it looks like the start of a very nice image!

Regards,
Dave Blandston

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On 5/27/2010 6:05 AM, Dream wrote:
> Therefore, here I ask for your help for how to render this scene for a
> realistical result? How to set the papemeters for drops meterial?

Try increasing max_trace_level... (I think it goes in global settings, I 
can't remember off-hand, so look it up in the docs)

-- 
~Mike

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Am 27.05.2010 13:05, schrieb Dream:

> Therefore, here I ask for your help for how to render this scene for a
> realistical result? How to set the papemeters for drops meterial?

For highest realism, you'd want to use

   finish {
     reflection { 0.0, 1.0 fresnel on }
     conserve_energy // not really necessary in this case
     ambient 0 diffuse 0
     specular ... // try it out
   }

At least that's the theory.

You need to make sure, however, that you do /not/ get reflections at the 
interface between the drop and the leaf, so you need to make the objects 
overlap a little bit. I guess that's your main problem ATM.

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clipka <ano### [at] anonymousorg> wrote:
> Am 27.05.2010 13:05, schrieb Dream:
>
> > Therefore, here I ask for your help for how to render this scene for a
> > realistical result? How to set the papemeters for drops meterial?
>
> For highest realism, you'd want to use
>
>    finish {
>      reflection { 0.0, 1.0 fresnel on }
>      conserve_energy // not really necessary in this case
>      ambient 0 diffuse 0
>      specular ... // try it out
>    }
>
> At least that's the theory.
>
> You need to make sure, however, that you do /not/ get reflections at the
> interface between the drop and the leaf, so you need to make the objects
> overlap a little bit. I guess that's your main problem ATM.



Thank you all for your answers.

According to what you all suggested above, I think the most possible problem is
caused by interface between raindrop nether surface and leaf upper surface. The
result image attached above is generated in the situation that the raindrop
nether surface is lower than the leaf upper surface, that is to say, the leaf
surface traverses the raindrop body.

What I want to ask now is that when the two objects (raindrop and leaf) have the
exact coincident interface (between raindrop nether surface and leaf upper
surface), which surface should be upper? The raindrop nether surface is upper or
lower than leaf upper surface?

Considering the fact, the raindrop is on the leaf surface, therefore I believe
the raindrop nether surface is upper than the leaf upper surface, am I
right？

Thank you!

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Mike Raiford <"m[raiford]!at"@gmail.com> wrote:
> On 5/27/2010 6:05 AM, Dream wrote:
> > Therefore, here I ask for your help for how to render this scene for a
> > realistical result? How to set the papemeters for drops meterial?
>
> Try increasing max_trace_level... (I think it goes in global settings, I
> can't remember off-hand, so look it up in the docs)
>
> --
> ~Mike

Hi, the max trace level  is 50, and the "reflection" and "refraction" are both
"on".

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Thank you all for your kindly reply.

The problem has been fixed by mainly two adjustment:

1. Make the raindrop nether surface a bit higher than leaf upper surface. Before
this operation I had made a mistake for an opposite direction.

2. Remove the shadow of raindrop.

Thank you all again.

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On 5/27/2010 6:49 AM, Dream wrote:
> clipka<ano### [at] anonymousorg>  wrote:
>> Am 27.05.2010 13:05, schrieb Dream:
>>
>>> Therefore, here I ask for your help for how to render this scene for a
>>> realistical result? How to set the papemeters for drops meterial?
>>
>> For highest realism, you'd want to use
>>
>>     finish {
>>       reflection { 0.0, 1.0 fresnel on }
>>       conserve_energy // not really necessary in this case
>>       ambient 0 diffuse 0
>>       specular ... // try it out
>>     }
>>
>> At least that's the theory.
>>
>> You need to make sure, however, that you do /not/ get reflections at the
>> interface between the drop and the leaf, so you need to make the objects
>> overlap a little bit. I guess that's your main problem ATM.
>
>
>
> Thank you all for your answers.
>
> According to what you all suggested above, I think the most possible problem is
> caused by interface between raindrop nether surface and leaf upper surface. The
> result image attached above is generated in the situation that the raindrop
> nether surface is lower than the leaf upper surface, that is to say, the leaf
> surface traverses the raindrop body.
>
> What I want to ask now is that when the two objects (raindrop and leaf) have the
> exact coincident interface (between raindrop nether surface and leaf upper
> surface), which surface should be upper? The raindrop nether surface is upper or
> lower than leaf upper surface?
>
> Considering the fact, the raindrop is on the leaf surface, therefore I believe
> the raindrop nether surface is upper than the leaf upper surface, am I
> right？
>
> Thank you!
>
Its random. Imho, this is, in some respects, a flaw in how the algorithm 
works. There is no "sorting" of the surfaces, to determine which one 
"should be" on top, or anything, you just have, "In this one case the 
math says surface A is on top, due to limits of precision, but the next 
pixel, it says its surface B." I am not even sure if you could do 
something like a bsp tree sort, to resolve those sorts of issues, but I 
wish someone would come up with something, because there are a lot of 
cases where an overlap, or a semi-exact surface to surface touch is 
closest to reality, but raytracing just won't allow it to happen. 
Anything in a glass, being a good example. lol

-- 
void main () {

     if version = "Vista" {
       call slow_by_half();
       call DRM_everything();
     }
     call functional_code();
   }
   else
     call crash_windows();
}

<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models, 
3D Content, and 3D Software at DAZ3D!</A>

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Do your raindrops have hollow and double_illuminate on? If not, it might  
make a difference.

-Nekar Xenos-

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> Do your raindrops have hollow and double_illuminate on? If not, it might
> make a difference.
>
> -Nekar Xenos-

hollow have absolutely nothing to do here. It's one and only function is 
to allow an object to contain a media.

As the drops are transparent (rgbt 1), double_illuminate will have no 
effect at all.

So, no, having those on can't make any difference.


Alain

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