Image to

http://news.povray.org/povray.newusers/thread/%3Cweb.52d0b932f649b333171348a80%40news.povray.org%3E/

Best regards,
Michael

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Download 'tops.png' (137 KB)

Preview of image 'tops.png'

> 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

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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

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.

If someone is interested in the code of this little exercise I will put it here
under a cc-0 licence.

Best regards,
Michael

Post a reply to this message

Attachments:
Download 'dancingelectrodes.mp4.mpg' (203 KB)

> 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.
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

Post a reply to this message

>> 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

Post a reply to this message

Alain <kua### [at] videotronca> wrote:
>
> Oups! I meant sky_sphere or using a large textured sphere around your scene.
>
Hello Alain, many thanks for your recommendations. They really helped. But of
course they prologend the rendering time a bit...

In the first abandoned approach I used a sky_sphere. I went for the second one
with the area_light and implemented your suggestions. Looks better IMO. But in
the end I made the scene just for fun to see if I can animate an ISO-CSG
structure in this way. In the first place my intent was to ask the original
author of this request (tops), what (s)he had in mind. But to learn more about
radiosity additionally is ever welcome.

Thanks,
Michael

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Attachments:
Download 'dancingelectrodes.mp4.mpg' (317 KB)