If I take a light and a glas-prism, I get a true rainbow.
Has anyone done something like that before ?
Can you sent me the scene file ?

Theo Gottwald
http://www.it-berater.org/smpov.htm

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Theo Gottwald * wrote:
> 
> If I take a light and a glas-prism, I get a true rainbow.
> Has anyone done something like that before ?

It has been done using photons + dispersion.

> Can you sent me the scene file ?

I don't have a working example handy but if you research those
features it shouldn't be too difficult for you to figure out.

-- 
Ken Tyler

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Yes, I've already tried a bit and mixed a red, green and blue spot light
which gives also a lot of colours.

The diffract-examples partially render to some "unnatural rainbows"
as the colours do not flow in each other but are separated like with a line.
Especially new_diffract.pov. I am not yet shure what I need to change that.

However I thought I ask if someone has something like that already.

thanks
--Theo


"Ken" <tyl### [at] pacbellnet> schrieb im Newsbeitrag
news:3D568171.4DC80935@pacbell.net...
>
>
> Theo Gottwald * wrote:
> >
> > If I take a light and a glas-prism, I get a true rainbow.
> > Has anyone done something like that before ?
>
> It has been done using photons + dispersion.
>
> > Can you sent me the scene file ?
>
> I don't have a working example handy but if you research those
> features it shouldn't be too difficult for you to figure out.
>
> --
> Ken Tyler

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In article <3d5683b3$1@news.povray.org>,
 "Theo Gottwald *" <The### [at] t-onlinede> wrote:

> Yes, I've already tried a bit and mixed a red, green and blue spot light
> which gives also a lot of colours.

That is not necessary, more work, and is much less accurate.


> The diffract-examples partially render to some "unnatural rainbows"
> as the colours do not flow in each other but are separated like with a line.
> Especially new_diffract.pov. I am not yet shure what I need to change that.

newdiffract.pov is not at all realistic, it uses a dispersion value far 
outside the usual range for a special effect. Usual values are much 
closer to 1, look at consts.inc for some values.
If you want smoother color blends, increase dispersion_samples. This 
will slow things down though...it is a tradeoff of speed or quality.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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Theo Gottwald * wrote:
>Yes, I've already tried a bit and mixed a red, green and blue spot light
>which gives also a lot of colours.
>
>The diffract-examples partially render to some "unnatural rainbows"
>as the colours do not flow in each other but are separated like with a line.
>Especially new_diffract.pov. I am not yet shure what I need to change that.

Is there an option to specify a light source as a beam trace (opposed to a
ray trace)?  The differance in that a ray is a line which doesn't have any
area (in in't cross section).  A beam represents the summing of a bunch of
rays that pass closely to the point of interest (location, eye).  The
closer the ray passes the more it is weighted (gaussian) contribution.  The
beam would smooth the rays.  However at least 8 extra  rays around the
center ray would have to be traced to represent a beam, so this could be
costly.


>
>However I thought I ask if someone has something like that already.
>
>thanks
>
>
>"Ken" <tyl### [at] pacbellnet> schrieb im Newsbeitrag
>news:3D568171.4DC80935[at]pacbell.net...
>>
>>
>> Theo Gottwald * wrote:
>> >
>> > If I take a light and a glas-prism, I get a true rainbow.
>> > Has anyone done something like that before ?
>>
>> It has been done using photons + dispersion.
>>
>> > Can you sent me the scene file ?
>>
>> I don't have a working example handy but if you research those
>> features it shouldn't be too difficult for you to figure out.
>>
>> --
>> Ken Tyler
>



ton### [at] xenomechanicscom

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In article <web.3d5739daafdcd0e888d4e3910@news.povray.org>,
 "Tony LaVigne" <ton### [at] xenomechanicscom> wrote:

> Is there an option to specify a light source as a beam trace (opposed to a
> ray trace)?  The differance in that a ray is a line which doesn't have any
> area (in in't cross section).  A beam represents the summing of a bunch of
> rays that pass closely to the point of interest (location, eye).  The
> closer the ray passes the more it is weighted (gaussian) contribution.  The
> beam would smooth the rays.  However at least 8 extra  rays around the
> center ray would have to be traced to represent a beam, so this could be
> costly.

The dispersion feature comes as close as is possible in POV by tracing 
multiple rays to sample the "beam". There is no single "point of 
interest" to compare each ray against because the entire scene can 
matter, it might be an arbitrary set of solid shapes or a pattern of 
color in a texture, or even volumetric media.

The solution is just to increase the dispersion samples until the 
splitting is not noticeable.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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