Hi, big thanks, so far. please let's continue.

I used "760.0*x*0.7   // Color?" because you wrote: "AxleRadius*x*0.7".
I don't need a red light, so I will change it. :-)

Right after you wrote "257,33", that is why I placed them right after,
too. What are these two numbers actually about, or for?
And where exactly to place them? After the vectors of the area_light as
replacement for "3,3"?

Vectors of the area_light:
< -1000.0, -1300.0, 0.0 > < 1000.0, -1300.0, 5000.0 >
What exactly do they describe? The illuminated area? Or the area
(rectangle) in which all lights are in? I might have to make some
changes to those two vectors, based on your answer. :-)

At the moment, I have this as light system, but the resulting image is
just showing a distant gray ring:
---------------------------

#if(IlluminationType="Lights")
 #declare MyLight = union
 {
  light_source
  {
   5000*z                   // Location
   rgb < 1.00000, 0.98824, 0.88235 > // Color
   area_light               // Type
   5000*z 760*0.7*x 257, 33 // Vectors
   adaptive 0               //
   area_illumination on     //
  }
  cylinder
  {
   0, 5000.0*z, 760.0
   pigment
   {
    radial
    color_map
    {
     [ 0.00 rgb  0.5 ]
     [ 0.05 rgbf < 0.8, 0.5, 0.2, 1.0 > ]
     [ 0.10 rgbf 1.0 ]
     [ 0.40 rgbf 1.0 ]
     [ 0.45 rgbf < 1.0, 0.7, 0.5, 1.0 > ]
     [ 0.50 rgb  0.5 ]
    }
    rotate 180*z
   }
//   interior_texture  // not yet in place. But shouldn't that cylinder
be hollow then?
   translate < 0.0, -10.0, 0.0 >
  }
 }
#end

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




On 14.02.2016 10:47, Alain wrote:
> area_light HabitatLength*z, AxleRadius*x*0.7, 257, 33 adaptive 0
> area_illumination
>
> cylinder{0, HabitatLength*z, AxleRadius
>  pigment{radial
>   color_map{[0 rgb 0.5][0.05 rgbf<0.8, 0.5, 0.2, 1>][0.1 rgbf 1]
>   [0.4 rgbf 1][0.45 rgbf<1, 0.7, 0.5, 1>][0.5 rgb 0.5]}
>  rotate 180*z}
> }

On 16.02.2016 14:10, Alain wrote:
> Le 16-02-15 05:21, Sven Littkowski a écrit :
>>     5000.0*z      // Location
> Yes, location of <0, 0, 5000>
>>     760.0*x*0.7   // Color?
> That makes your light red. It evaluate to rgb <760*0.7, 0, 0>
>>     257, 33       // ?
> This WILL cause an error and stop parsing.
> MUST folloow both area_light AND the two axis
>>     area_light    // Type
>>   // The POV-Ray docu says vectors and sizes are required for area light
>>     < -1000.0, -1300.0, 0.0 > < 1000.0, -1300.0, 5000.0 > 3, 3 // OK?
> That can be ok. This define a rectangle set -1300 unit down the y axis,
> and set at an angle.
> 
> You first define the location of the light, then it's colour.
> After that, you add the area_light parameters and other light options.
> 
> It's as follow, after location and colour/intensity:
> area_light
> First size of the area light as an axis
> Second size of the area light also as an axis
> For both axis, the shortcut n*x, n*y and n*z are legal.
> Number of samples along the first axis
> Number of samples along the second axis
> 
> For the axis, it's usualy beter to define them along the reference axis.
> After that, if needed, you can rotate the light as a whole to orient the
> plane as needed. That's much easier than giguring the correct values for
> the axis. Alternatively, it's possible to use some axis manipulation
> macros to calculate the correct values.
> 
> It's followed by the other options in any order:
> 
> area_illumination will affect the illumination of objects that are close
> to the light's location.
> 
> adaptive turn on the adaptive subsampling. The keyword is followed by an
> integer value that set the minimal number of initial subsampling.
> A value of 0 will start with only the 4 corners, and if they are not all
> visible or invisible from a given point, then subdivision will occur.
> A value of 1 will start with a 3 by 3 array, adaptive 2 will start with
> a 5 by 5 array, subjected to the actual number of sublights in that
> direction.
> adaptive allow the use of large number of samples with minimal
> performance hit.
> 
> circular moves the sublights inward so that they reside within a circle
> or ellips.
> orient will pivot the sublights array so that it's always facing any
> point bein evaluated. It MUST be used with circular and the two axis
> must be ov the same length and the number of samples must be the same in
> both directions.
> 
> jitter will randomly move the sublights to reduce banding. If used with
> antialiasing, each antialiasing samples will have a different jittering
> of the sublights.
> 
> area_light is compatible with spotlight, cylinder, projected_through,
> parallel.
> It's pointless for a shadowless light.
> 
> Correctly writing your sample:
> light_source{
>  Location
>  Colour
>  area_light // turn on the area_light feature
>  5000*z 760*0.7*x //surface covered be the area_light
>  257 33 //number of samples along the long and short axis
>  jitter // very small effect in this case, help reduce banding
> }
> 
> This area_light is parallel with the X-Z plane, and it's longest extent
> is alligned along the z axis.
> If location is set for 500*y or <0, 500, 0>, the light will be located
> within this square:
> <-16.5, 500, -2500> <16.5, 500, 2500>
> 
> 
> 
> Alain

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