POV-Ray : Newsgroups : povray.newusers : sky_sphere gradient coarsened on reflective curved surface Server Time
29 Jul 2024 08:22:24 EDT (-0400)
  sky_sphere gradient coarsened on reflective curved surface (Message 1 to 2 of 2)  
From: huskeypm
Subject: sky_sphere gradient coarsened on reflective curved surface
Date: 10 Jun 2006 13:45:00
Message: <web.448b040d82d3d50c3457e9340@news.povray.org>
Hi
I have a simple scene primarily consisting of a molecule with reflective
spheres and a sky_sphere.  From the camera's perspective, the color
gradient for the sky_sphere seems smooth; however, the reflection in the
spheres (of whats behind tyhe camera) shows a much coarser gradient (4
shades of blue).

My questions are the following
1.  my sky_sphere is only supposed to be 'light' at one end - why is it that
my set up has light spots on both sides (ie whats behind the camera)?
2.  despite this, why is the reflected gradient not smooth like the sky?

I have provided http links to the image as well as the source files.  I have
included the entire pov file in case the problem relates to global
conditionans and not my finish.  BTW: i rendered this with the +Q11 +A0.3
flags.

thanks in advance for your help!
pete


// files
http://pkh.caltech.edu/public_files/999o.jpg
http://pkh.caltech.edu/public_files/999osimp.pov
http://pkh.caltech.edu/public_files/test.inc

// 999osimp.pov
#version 3.5;   // this scene uses POVRAY 3.5 syntax

#include "colors.inc"
#include "glass.inc"
#include "textures.inc"
#include "functions.inc"

global_settings {
  assumed_gamma 2.0   //TURNS SCREEN BLUE
  max_trace_level 8
    photons {
      spacing 0.02                 // specify the density of photons
    }

  radiosity {
    count 750                      // higher -> higher quality (1..1600)
[35]
    nearest_count 10              // higher -> higher quality (1..10) [5]
    recursion_limit 10            // how much interreflections are
calculated (1..5+) [3]
  }
}

// ------ COLORS ---------
#declare WAT_TEXT = texture{
                Green_Glass
                pigment { rgb <0.5, 0.5, 0.6> }

                finish {
                        ambient 0.05 diffuse 0.55
                        brilliance 3.0 phong 0.8 phong_size 120
                        reflection 0.3
                        specular 0.8
                        roughness 0.013
   //reflection { 0.03, 1 }
                }
}

#declare ATM_FINISH = finish {
 // should total about 1.0
 reflection {0.6, metallic}
 ambient 0.01
 diffuse 0.3
 specular 0.9
 roughness 0.001
 conserve_energy
}

#declare SURF_FINISH = finish {specular 0.9 roughness 0.001 ambient rgb
<0.3,0.3,0.3>}
#declare H_tex = texture { pigment { color rgbf <0.776,0.886,1.000,0.000> }
finish{ ATM_FINISH }}
#declare C_tex = texture { pigment { color rgbf <0.580,0.580,0.580,0.000> }
finish{ ATM_FINISH }}
#declare N_tex = texture { pigment { color rgbf<0.090, 0.172, 0.811, 0.0> }
finish{ ATM_FINISH }}
#declare O_tex = texture { pigment { color rgbf<0.662, 0.122, 0.047, 0.0> }
finish{ ATM_FINISH }}
#declare P_tex = texture { pigment { color rgbf<1.000, 0.659, 0.086, 0.0> }
finish{ ATM_FINISH }}
#declare S_tex = texture { pigment { color rgbf<0.298, 0.800, 1.000, 0.0> }
finish{ ATM_FINISH }}
#declare X_tex = texture { pigment { color rgbf<0.624, 0.624, 0.624, 0.0> }
finish{ ATM_FINISH }}
#declare bnd_tex = texture { pigment { color rgbf<0.624, 0.624, 0.624, 0.0>
} finish{ BOND_FINISH}}

#declare r_Atm = 0.200;   // atom radius
#declare r_Bnd = 0.200;   // bond radius
#declare r_HBnd = 0.075;   // H-bond radius
#declare CA_relativeSize = 1.000;   // enlargement factor for CA
#declare rDOT_SURF = 0.05; // radius for accessible surf. dots.
#declare VDW_factor = 0.200;   // changing this value will alter the radius
of "joining" atoms
#declare SMALL = 0.3; // for scalling atoms down

#declare rH = 1.00 * VDW_factor ;
#declare rH_ = 1.10 ;
#declare rHs_ = rH_ * SMALL;
#declare rC = 1.00 * VDW_factor ;
#declare rC_ = 1.70 ;
#declare rCs_ = rC_ * SMALL;
#declare rN = 1.00 * VDW_factor ;
#declare rN_ = 1.50 ;
#declare rNs_ = rN_ * SMALL;
#declare rO = 1.00 * VDW_factor ;
#declare rO_ = 1.40 ;
#declare rOs_ = rO_ * SMALL;
#declare rNa = 1.00 * VDW_factor ;
#declare rNa_ = 1.10 ;
#declare rSi = 1.00 * VDW_factor ;
#declare rSi_ = 1.10 ;
#declare rP = 1.00 * VDW_factor ;
#declare rP_ = 1.90 ;
#declare rPs_ = rP_ * SMALL;
#declare rS = 1.00 * VDW_factor ;
#declare rS_ = 1.85 ;
#declare rSs_ = rS_ * SMALL;
#declare rK = 1.00 * VDW_factor ;
#declare rK_ = 1.10 ;

//--------------------------------------------------------------------
//--------------------------------------------------------------------
//--------------------------------------------------------------------
//--------------------------------------------------------------------
//--------------------------------------------------------------------

//************ CAMERA *********

camera {
        location < -0.0, 0.25,13.5 >  // get closer to <0,0,0> to zoom in on
the model
        right <2000/1500, 0, 0>  // **NOTE:** do not forget to adjust this
value according to final Width/Height rendering
        look_at <0, 0.25, 0>
}

//************ OBJECTS *********
#include "test.inc"
object{
 A0_shape
        scale 1.2
        translate< -0.0,-0.3,-2.5>
        photons { collect off }
 photons{
    target
    reflection on
    refraction on
 }
}

light_source {
   <0, 0, 0> colour rgb 1 //red 1.0 green 0.7

   looks_like {
      sphere { <0.0, 0.0, 0.0>, 50.0
         pigment { colour rgb 0.7 }//red 0.7 green 0.0 blue 0.5 filter 0.95
}
         finish {
  ambient 1.5  // bright
  diffuse 0.0
 }
      }
   }
  photons {
    reflection off
    refraction on
  }

   translate <-552.5, 00.0, -1500.0>
}

light_source{
 < 0.000, 40.000,  40.000 > color rgb 1
  photons {
    reflection off
    refraction on
  }
}

// Now draw the sky
sky_sphere{
    pigment {
      gradient y
      color_map {
        [0.000 0.001 color rgb <1.0, 1.0, 0.8>
                     color rgb <1.0, 1.0, 1.0>]
        [0.001 0.006 color rgb <1.0, 1.0, 1.0>
                     color rgb <0.7, 0.7, 1.0>]
        [0.016 5.000 color rgb <0.7, 0.7, 1.0>
                     color rgb <0.0, 0.0, 0.4>]
      }
      scale 0.65
      translate -1
    }
    //rotate -135*x
    rotate 89*x
    rotate 20*y

}

// fog ---------------------------------------------------------------

fog{
     fog_type   2      distance   40
     color      rgb<0.9,.9,0.9>
     fog_offset 0.1
     fog_alt    0.7
     turbulence 0.2
}
// water
--------------------------------------------------------------------
// floor
plane{ <0,1,0>, 0  translate<0,-30.5,0>
       texture{pigment{ rgb <0.1,0.1,0.1>}//LightWood*0.7}
               normal {bumps 0.25 scale 0.05}
               finish {ambient 0.15 diffuse 0.85}}}
// water surface
merge {
        // may need to shift coords in case of artifacts
    difference {
        box {   <-500, -10.001, -1000>, <500, -1, 100> }
        box {   <-5.001,-11.001,-20.001>, <05.001, -.999, 30.001> }

        texture{ WAT_TEXT}
        photons { collect off }
        scale <2.0,1,0.3>*2  //rotate<0,10,0>
    }

    box { //<-5, -50, -10>, <5, -1, 0>
        <-5, -11, -20.0>, <5, -1, 30.0>
        texture{
  WAT_TEXT

 }//pigment{ rgb <0.9,0.1,0.1>}}
        interior{
  I_Glass
  ior 1.5 media
  {scattering { 2 <0.5, 0.65, 0.4> }}
 }
        scale <2.0,1,0.3>*2  //rotate<0,10,0>
  }
}


Post a reply to this message

From: Alain
Subject: Re: sky_sphere gradient coarsened on reflective curved surface
Date: 11 Jun 2006 10:05:40
Message: <448c2334$1@news.povray.org>
huskeypm nous apporta ses lumieres en ce 10/06/2006 13:40:
> Hi
> I have a simple scene primarily consisting of a molecule with reflective
> spheres and a sky_sphere.  From the camera's perspective, the color
> gradient for the sky_sphere seems smooth; however, the reflection in the
> spheres (of whats behind tyhe camera) shows a much coarser gradient (4
> shades of blue).
> 
> My questions are the following
> 1.  my sky_sphere is only supposed to be 'light' at one end - why is it that
> my set up has light spots on both sides (ie whats behind the camera)?
> 2.  despite this, why is the reflected gradient not smooth like the sky?
> 
> I have provided http links to the image as well as the source files.  I have
> included the entire pov file in case the problem relates to global
> conditionans and not my finish.  BTW: i rendered this with the +Q11 +A0.3
> flags.
> 
> thanks in advance for your help!
> pete
> 
> // Now draw the sky
> sky_sphere{
>     pigment {
>       gradient y
>       color_map {
>         [0.000 0.001 color rgb <1.0, 1.0, 0.8>
>                      color rgb <1.0, 1.0, 1.0>]
>         [0.001 0.006 color rgb <1.0, 1.0, 1.0>
>                      color rgb <0.7, 0.7, 1.0>]
>         [0.016 5.000 color rgb <0.7, 0.7, 1.0>
>                      color rgb <0.0, 0.0, 0.4>]
>       }
>       scale 0.65 ???
Why scale small, you cause repetitions of the pattern.
>       translate -1
>     }
>     //rotate -135*x
>     rotate 89*x
>     rotate 20*y
> 
> }
> 
The gradient repeat 2 times in the sky_sphere, by scaling it by 0.65, you make it
repeat a little 
more than 3 times.
Solution: use scale 2 and the banding will go away.

-- 
Alain
-------------------------------------------------
Bend the facts to fit the conclusion. It's easier that way.


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