>> Alain <kua### [at] videotronca> wrote:

>>>> Image to
>>>>
>>>>
http://news.povray.org/povray.newusers/thread/%3Cweb.52d0b932f649b333171348a80%40news.povray.org%3E/
>>>>
>>>>
>>>> Best regards,
>>>> Michael
>>>>
>>>
>>> It looks like your textures have to much ambient, making reliefs
>>> difficult to see.
>>> The default value is 0.1, and it's often a good idea to use some smaller
>>> values down to zero.
>>> If some areas are then to dark, you can use a shadowless fill light,
>>> possibly having a different tint.
>>>
>>>
>>> Alain
>>
>> As all I know ambient is set to zero using radiosity. The pigments are
>> red, blue
>> and yellow from colors.inc simply. There are some radiosity artefacts
>> present
>
> In this case, I'd suggest using some actual light_source instead of a
> plain background.

Oups! I meant sky_sphere or using a large textured sphere around your scene.

> Another solution would be to use a light_dome with some pattern, like a
> simple gradient, so that the radiosity illumination is no longer uniform.
>
>>
>> Just for the fun of it I rendered a small animation with "undulated"
>> electrodes...
>>
>> I used Alain's approach modifying only frequency and amplitude of the
>> sinus wave
>> for the electrodes. The main trick was to rebuild the electrodes as an
>> isosurface as Alain proposed. Using Chris Hormann's ISO-CSG-library it
>> was done
>> quickly. For the box object at the ground I used the function
>>
>>     function { fn1(x,y+sin(clock-sqrt(x*x+z*z)*5)/4,z)}
>>
>> with
>>
>>     #declare fn1 = IC_Box(<-20,-1,-10>,<20,1,10>)
>>
>> from the ISO-CSG library too. I exchanged the radiosity lighting here
>> with a
>> small area light since the radiosity artefacts within the animation were
>> annoying completely.
>
> For that, you need to adjust the radiosity settings.
> Some suggestions:
>
> Reduce pretrace_end to 0.01, 0.005, 0.0025 or even less, as long as it
> still larger than a single pixel.
> Try pretrace_end 2/image_width to use 2 pixels tiles on the final
> pretrace step.
>
> Reduce low_error_factor. The default of 0.5 is often to large, especialy
> for animations.
>
> Use the radiosity sample direction pool: count 100 1000. Use a large
> second value, 10 to 100 or more times larger than the base count value.
>
> Slightly increase error_bound, but slightly decrease minimum_reuse.
>
>>
>> If someone is interested in the code of this little exercise I will
>> put it here
>> under a cc-0 licence.
>>
>> Best regards,
>> Michael
>>
>
> Alain

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