Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
> Is there any location, where "this" and "dens_cloud" are defined? I
> feel, I am missing some previous code here. :-)
>
> ---

> http://www.avg.com

"dens_cloud" is mine. It outputs the shape of the cloud from a function, I
usually use function to control the pattern. You can use your own density
pattern instead.

#include "functions.inc"

#declare f_test =
function(x,y,z) {
0.32*sum(i, 0, 4, pow(abs(f_noise3d(x*pow(2, i)/0.4, y*pow(2, i)/0.4, z*pow(2,
i)/0.4)), 2.5)/pow(2.0, i) )
}



#declare f_cloud_base =
function(x,y,z) {
0.5 - f_test(x,y,z)*3*3*z*exp(-3*z) - 0.32*3*3*z*exp(-3*z)
}


#declare dens_cloud =
density{
    function{0.5 - 0.2*f_cloud_base(x,y,z)}
    color_map{
        [0   rgb 0]
        [0.5 rgb 0]
        [0.56 rgb 1]
        [1   rgb 1]
    }
}

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Sunset:

this image I just assigned scattering media for the cloud. You can see the cloud
is too dark.
Even I set the extinction smaller than 1.0(this is equal emission some lights)


// cloud
box{
<-5.01, -5.01, 0>, <5.01, 5.01, 1>
hollow
    material{
        texture{
            pigment{rgbt<0,0,0,1>}
            finish{ambient 0 diffuse 0}
        }
        interior {
            media{
                samples 8

                scattering{
                3, rgb< 1.00, 0.784, 0.746 >*8.0 //8.0
                extinction 0.8
                }
                density {
                dens_cloud
                }
            }
        }
    }
scale 2
translate <0,0,0.4>
}

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Attachments:
Download 'mountain scene2 1 sunset only scattering.png' (164 KB)

Preview of image 'mountain scene2 1 sunset only scattering.png'

"And" <49341109@ntnu.edu.tw> wrote:
> Sunset:
>
> this image I just assigned scattering media for the cloud. You can see the cloud
> is too dark.
> Even I set the extinction smaller than 1.0(this is equal emission some lights)
>

Too dark is caused by lacking of multiple scattering, so I fill-in some light
with emission for it.



    material{
        texture{
            pigment{rgbt<0,0,0,1>}
            finish{ambient 0 diffuse 0}
        }
        interior {

            media{
                samples 8

               emission rgb<3.73, 2.92*0.75*0.161, 2.78*0.65*0.01 >*0.15

                density {
                dens_cloud2
                }
            }
            media{
                samples 8
                emission rgb<1.00, 0.784*0.75*0.161, 0.746*0.65*0.01 >*1.0
                         // notice this is
                         // vdot(<1.00, 0.784*0.75, 0.746*0.65>,
                         //      <1.00, 0.161, 0.01>)
                         //      ^^^^^^^^^^^^^^^^^^^  this is my sun color

                scattering{
                3, rgb< 1.00, 0.784, 0.746 >*8.0 //this is the same, not change
                extinction 0.8
                }
                density {
                dens_cloud
                }
            }
        }
    }


for the sunset I use rgb<1.00,0.161,0.01>*strength for my parallel light as sun
light. It is from a sunset photo, I measured the color.

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Attachments:
Download 'mountain scene2 1 sunset.png' (181 KB)

Preview of image 'mountain scene2 1 sunset.png'

"And" <49341109@ntnu.edu.tw> wrote:
> "And" <49341109@ntnu.edu.tw> wrote:
> > Sunset:
> >
> > this image I just assigned scattering media for the cloud. You can see the cloud
> > is too dark.
> > Even I set the extinction smaller than 1.0(this is equal emission some lights)
> >
>
> Too dark is caused by lacking of multiple scattering, so I fill-in some light
> with emission for it.


Another view:

Post a reply to this message

Attachments:
Download 'mountain scene2 2.png' (78 KB)

Preview of image 'mountain scene2 2.png'

On 01.12.2017 06:34, And wrote:
> Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
>> On your last (high-attitude) cloud image, i would apply a tiny scale
>> attribute to your clouds. make them just a little bit flatter, maybe 10
>> to 20% only.
>>
> 
> Hmm really?
> 
>> Your low-attitude cloudy-mountains image shows clouds that are not dense
>> enough in their center, not hiding the mountains well enough yet. I
>> believe, if you increase the density inside the centers, you should be
>> finished with the cloud coding. :-)
>>
> 
> My approach will not allow me to rise the density much more, or it shows more
> artifact. That's one of what I said the limit of the media previous. It can
> simulate not so dense cloud, but more density it can't.
> 
> The two pictures that I last post is in the same cloud setting. Just change the
> camera position. I want to express that my approach can simulate cloud nearing
> the physical reality, not just an inconstant result.
>> ---

>> http://www.avg.com
> 
> 
> 
The images still look nice. Sad only, that I self have no understanding
of media, I wished I could help here. Sounds like you should propose a
new feature inside the BETA section of this newsgroup, or expanding
existing features to make it possible to increase the density further.

Post a reply to this message

On 01.12.2017 07:57, And wrote:
> "And" <49341109@ntnu.edu.tw> wrote:
>> "And" <49341109@ntnu.edu.tw> wrote:
>>> Sunset:
>>>
>>> this image I just assigned scattering media for the cloud. You can see 
the cloud
>>> is too dark.
>>> Even I set the extinction smaller than 1.0(this is equal emission some 
lights)
>>>
>>
>> Too dark is caused by lacking of multiple scattering, so I fill-in some 
light
>> with emission for it.
> 
> 
> Another view:
> 
I think I understand now: this is not about my scene, but about a scene
of yours. :-D

---

http://www.avg.com

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Am 01.12.2017 um 20:42 schrieb Sven Littkowski:
> The images still look nice. Sad only, that I self have no understanding
> of media, I wished I could help here. Sounds like you should propose a
> new feature inside the BETA section of this newsgroup, or expanding
> existing features to make it possible to increase the density further.

The issue isn't so much whether it is /possible/ to increase the
density, but rather whether doing so gives /realistic results/.

The problem is that the scattering media model is designed for cases
where the media's density is non-uniform, but low enough that the single
scattering contribution is dominant (i.e. a typical light ray will be
deflected from its initial direction at most once), and the multiple
scattering contribution (i.e. light that is deflected from its initial
direction more than once) is negligible.

Compare this to the subsurface light transport model, which is
specifically designed for cases where the density is pretty much
uniform, but high enough that the multiple scattering contribution is
dominant.


To extend the scattering media model in such a manner that it gives
reasonably realistic results for high-density media, a monte-carlo-ish
rendering approach would have to be used, where secondary rays would be
shot here and there along the light's path (even recursively). Expect
noisy results and/or high rendering times.

This is in fact on my wishlist, but other stuff takes priority.

Post a reply to this message

On 01.12.2017 15:17, clipka wrote:
> Am 01.12.2017 um 20:42 schrieb Sven Littkowski:
>> The images still look nice. Sad only, that I self have no understanding
>> of media, I wished I could help here. Sounds like you should propose a
>> new feature inside the BETA section of this newsgroup, or expanding
>> existing features to make it possible to increase the density further.
> 
> The issue isn't so much whether it is /possible/ to increase the
> density, but rather whether doing so gives /realistic results/.
> 
> The problem is that the scattering media model is designed for cases
> where the media's density is non-uniform, but low enough that the single
> scattering contribution is dominant (i.e. a typical light ray will be
> deflected from its initial direction at most once), and the multiple
> scattering contribution (i.e. light that is deflected from its initial
> direction more than once) is negligible.
> 
> Compare this to the subsurface light transport model, which is
> specifically designed for cases where the density is pretty much
> uniform, but high enough that the multiple scattering contribution is
> dominant.
> 
> 
> To extend the scattering media model in such a manner that it gives
> reasonably realistic results for high-density media, a monte-carlo-ish
> rendering approach would have to be used, where secondary rays would be
> shot here and there along the light's path (even recursively). Expect
> noisy results and/or high rendering times.
> 
> This is in fact on my wishlist, but other stuff takes priority.
> 

Thank you for this insight.

I think, looking to the list of persons actively involved in the
developing, POV-Ray needs again some more promotion. It is such a
unique, great, possibilities-loaded render engine, it deserves to be
connected to all school and university students. I think, we really need
many more developers who are into POV-Ray rendering. But that is just my
personal opinion.

---

http://www.avg.com

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For some strange reason, it seems I am unable to change the location of
the two colors inside my pigment_maps ("MyHull" texture and "MyInterior"
texture, both at the top of the code), even when changing the numeric
values. Strange.

Can anyone of you test and find out, if you encounter the same problem?

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

#declare MyHullOutsideBottom = texture
{
 pigment { color rgbt < 0.8039216,  0.5882353,  0.29411765, 0.00 > }
// 1.0, 0.0, 0.0
}

#declare MyHullOutsideTop = texture
{
 pigment { color rgbt < 0.4039216, 0.1882353, 0.09411765, 0.75 > }
}

#declare MyHull = texture
{
 gradient y
 texture_map
 {
  [ 0.00 MyHullOutsideBottom ] // Hull   Bronze_Metal /**/
  [ 0.45 MyHullOutsideBottom ] // Hull
/*  [ 0.25 MyHullOutsideTop    ] // Lower Deck Window Stripe
  [ 0.28 MyHullOutsideTop    ] // Lower Deck Window Stripe
  [ 0.28 MyHullOutsideBottom ] // Cupola Base
  [ 0.35 MyHullOutsideBottom ] // Cupola Base
  [ 0.35 MyHullOutsideTop    ] // Cupola
  [ 0.42 MyHullOutsideTop    ] // Cupola
  [ 0.42 MyHullOutsideBottom ] // Cupola Railing
  [ 0.52 MyHullOutsideBottom ] // Cupola Railing
*/  [ 0.45 MyHullOutsideTop    ] // Cupola
  [ 1.00 MyHullOutsideTop    ] // Cupola
 }
 translate < 0.0, -4.8812, 0.0 >
 scale -1.0*(4.8812*2.85)
}

#declare MyHullInsideBottom = texture
{
 pigment { color rgb < 0.7843137,  0.654902,  0.4156863 > }
}

#declare MyHullInsideTop = texture
{
 pigment { color rgbt < 0.4039216,  0.1882353,  0.09411765, 0.75 > }
}

#declare MyInterior = texture
{
 gradient y
 texture_map
 {
  [ 0.00 MyHullInsideBottom ] // Hull   Bronze_Metal /**/
  [ 0.45 MyHullInsideBottom ] // Hull
/*  [ 0.25 MyHullInsideTop    ] // Lower Deck Window Stripe
  [ 0.28 MyHullInsideTop    ] // Lower Deck Window Stripe
  [ 0.28 MyHullInsideBottom ] // Cupola Base
  [ 0.35 MyHullInsideBottom ] // Cupola Base
  [ 0.35 MyHullInsideTop    ] // Cupola
  [ 0.42 MyHullInsideTop    ] // Cupola
  [ 0.42 MyHullInsideBottom ] // Cupola Railing
  [ 0.52 MyHullInsideBottom ] // Cupola Railing
*/  [ 0.45 MyHullInsideTop    ] // Cupola
  [ 1.00 MyHullInsideTop    ] // Cupola
 }
 translate < 0.0, -4.8812, 0.0 >
 scale -1.0*(4.8812*2.85)
}

camera
{
 /*ultra_wide_angle*/ //angle 20
 location  < -25.0 , 0.0 , 0.0 >
 //right     x*image_width/image_height // not needed for v3.8
 look_at   < 0.0 , 0.0 , 0.0 >
}

light_source
{
 < -500.0, 100.0, 500.0 >
 color 1.0 * 1.3//< 1.0,  0.62353,  0.46667 >*2
}



#declare HomeBasic = blob
{
 threshold 0.35
 sphere { < 0.0, 0.0, 0.0 > 26.00 1.85 scale < 1.01, 0.25, 1.01 > } //
9.7624 meter tall (-4.8812 m to 4.8812 m) and exactly 19 meter usable
inside radius (38 meter diameter)
 cylinder { < 0.0, 0.0, 0.0 > < 19.0, 0.0, 0.0 > 4.5 0.85 rotate < 0.0,
000.0, 0.0 > }
 cylinder { < 0.0, 0.0, 0.0 > < 19.0, 0.0, 0.0 > 4.5 0.85 rotate < 0.0,
120.0, 0.0 > }
 cylinder { < 0.0, 0.0, 0.0 > < 19.0, 0.0, 0.0 > 4.5 0.85 rotate < 0.0,
240.0, 0.0 > }
}

#declare HomeExact = difference
{
 object { HomeBasic }
 cylinder { < 20.0, 0.0, 0.0 > < 25.0, 0.0, 0.0 > 5.0 rotate < 0.0,
000.0, 0.0 > }
 cylinder { < 20.0, 0.0, 0.0 > < 25.0, 0.0, 0.0 > 5.0 rotate < 0.0,
120.0, 0.0 > }
 cylinder { < 20.0, 0.0, 0.0 > < 25.0, 0.0, 0.0 > 5.0 rotate < 0.0,
240.0, 0.0 > }
}

#declare HomeNegative = difference
{
 box { < -25.0, -10.0, -25.0 > < 25.0, 10.0, 25.0 > }
 object { HomeExact }
}

#declare MyInteriorWalls = difference
{
 //  cylinder { < 0.0,  4.8812, 0.0 > < 0.0,  4.9812, 0.0 > 05.0 pigment
{ color rgb < 0.5098039,  0.3137255,  0.2156863 > } } // Ceiling -
5.0812 m above main deck
 cylinder { < 0.0, -1.30, 0.0 > < 0.0, -1.20, 0.0 > 24.0 pigment { color
rgb < 0.5098039,  0.3137255,  0.2156863 > } } // Main Deck - usable
diameter: exactly 19 meters/units - deck thickness: 0.1 meters/units
 cylinder { < 0.0, -4.30, 0.0 > < 0.0, -4.20, 0.0 > 10.0 pigment { color
rgb < 0.5098039,  0.3137255,  0.2156863 > } } // Bottom Deck - usable
diameter: exactly 19 meters/units - ceiling height: exactly 3 meters /units

 union
 {
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 000.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 030.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 060.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 090.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 120.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 150.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 180.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 210.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 240.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 270.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 300.0,
0.0 > }
  box { < 10.0, -4.2, -0.05 >  < 25.0, -1.3, 0.05 > rotate < 0.0, 330.0,
0.0 > }
  texture { MyHullInsideBottom }
  rotate < 0.0, 15.0, 0.0 >
 }
 object { HomeNegative }
}

#declare HomeHollow = difference
{
 object { HomeExact texture { MyHull } }
 object { HomeExact scale < 0.999,0.996,0.999 > texture { MyInterior }
/*pigment { color rgbt < 0.8039216,  0.5882353,  0.29411765, 0.00 > }*/ }
}

#declare HomeWithInterior = union
{
 object { HomeHollow }
 object { MyInteriorWalls }
}

#declare LightsOrangeRings = union
{
 torus { 2.475 0.025 rotate < 0.0, 0.0, 90.0 > translate < 20.0, 0.0,
0.0 > rotate < 0.0, 000.0, 0.0 > }
 torus { 2.475 0.025 rotate < 0.0, 0.0, 90.0 > translate < 20.0, 0.0,
0.0 > rotate < 0.0, 120.0, 0.0 > }
 torus { 2.475 0.025 rotate < 0.0, 0.0, 90.0 > translate < 20.0, 0.0,
0.0 > rotate < 0.0, 240.0, 0.0 > }
 pigment { color rgb < 0.8784314,  0.2,  0.003921569 > }
 finish { emission 1.0  }
}

#declare HomeLights = union
{
 object { HomeWithInterior }
 object { LightsOrangeRings }
 light_source
 {
  < 0.0, 5.5, 0.0 >
  color rgb 0.2
 }
// cylinder { < 0.0, -1.3, 0.0 > < 0.0, -1.19, 0.0 > 19.0 pigment {
color rgb < 0.145098,  0.1921569,  0.05882353 > } } // measuring deck
diameter (do not use)
}

object { HomeLights scale 0.8 translate < 0.0, 0.0, 0.0 > rotate < 0.0,
000.0, 0.0 >}

---
Diese E-Mail wurde von AVG auf Viren geprüft.
http://www.avg.com

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See the image. I tried successlessly to raise the upper edge of the
sand-brown area in my pigment_map...


---
Diese E-Mail wurde von AVG auf Viren geprüft.
http://www.avg.com

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Attachments:
Download 'sl - cloud cities.png' (45 KB)

Preview of image 'sl - cloud cities.png'