I'm new, please be kind.

I have simple scene. the only source of light is from a point light source
projecting through a slit in a wall that then falls on a prism.  I want the
resulting rainbow to illuminate the scene.

I have the scene set up and it works nicely, except the image produced is
too
dark. What can I do?

I cannot find any info on how to adjust the sensitivity of the camera.  I
cannot see how to get the same effect from spot lights or other light
sources as I need the slit shaped light source. Also, would spotlights
actually be brighter?

I would post the scene and image but I'm not allows to in this group -
should I ask in another group?

Regards,
steven

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Steven Borley wrote:
> I'm new, please be kind.
> 
> I have simple scene. the only source of light is from a point light source
> projecting through a slit in a wall that then falls on a prism.  I want the
> resulting rainbow to illuminate the scene.
> 
> I have the scene set up and it works nicely, except the image produced is
> too
> dark. What can I do?

If the light is just too dark, just raise the RGB-Value on the 
lightsource. If that doesn't work, why not post the image as a jpeg in 
p.b.images and ask there? Descriptions of images often don't get as many 
useful answers as showing the image itself. :-)

Regards,
Tim

-- 
aka "Tim Nikias"
Homepage: <http://www.nolights.de>

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Steven Borley wrote:
> I'm new, please be kind.
> 
> I have simple scene. the only source of light is from a point light source
> projecting through a slit in a wall that then falls on a prism.  I want the
> resulting rainbow to illuminate the scene.
> 
> I have the scene set up and it works nicely, except the image produced is
> too
> dark. What can I do?

A) as told, you could increase the RGB value

B) if I understood your image correctly, you could increase the light
sources (ie. put n+1 light sources in 'bout the same place)

C) if using radiosity, you could possibly increase the brightness -value

D) check your gamma settings

> I would post the scene and image but I'm not allows to in this group -
> should I ask in another group?

For images there's povray.binaries.images and for scene files there's
povray.binaries.scene-files. These are often mentioned as p.b.i and p.b.s-f.

> Regards,
> steven

-- 
Eero "Aero" Ahonen
   http://www.zbxt.net
      aer### [at] removethiszbxtnetinvalid

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Steven Borley nous apporta ses lumieres en ce 24/09/2006 05:56:
> I'm new, please be kind.
> 
> I have simple scene. the only source of light is from a point light source
> projecting through a slit in a wall that then falls on a prism.  I want the
> resulting rainbow to illuminate the scene.
> 
> I have the scene set up and it works nicely, except the image produced is
> too
> dark. What can I do?
> 
> I cannot find any info on how to adjust the sensitivity of the camera.  I
> cannot see how to get the same effect from spot lights or other light
> sources as I need the slit shaped light source. Also, would spotlights
> actually be brighter?
> 
> I would post the scene and image but I'm not allows to in this group -
> should I ask in another group?
> 
> Regards,
> steven
> 
> 
> 
You can use a value greater than 1 for the light.
You can use a filter or transmit value greater than 1 for the prism: this will 
effectively amplify the light as it goes trough the prism. A pigment like "rgbt 
2" is legal if not physicaly correct.
A spot_light is not brighter than a point_light. The rays of light outside of 
the illumination cone are just suppressed.
You are right: there is no other way to get a rectangular light beam than to use 
  a slit mask.
You need photons if you want the spectrum to apears projected on your scene.
You need radiosity if you want that spectrum to in turn illuminate the rest of 
the scene.
If you use scattering media to make the beam visible and use radiosity, there is 
NO way that the scattered light can illuminate the scene. The "media on" 
radiosity option only allows emissive media to light the surrounding.

If the scene file is relatively short (less than 2K), it's possible to place 
it's text here, but it's beter on povray.binaries.scene-files.
Post the images on povray.binaries.images.


-- 
Alain
-------------------------------------------------
'hAS ANYONE SEEN MY cAPSLOCK KEY?'

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Tim, Eero, and Alain, thank you so much.

It has taken me some time to read through an understand your replies.  I
didn't realise I could have light values that exceeded 1.0 - don't know but
it just didn't occur to me.  First thing I did was to change my light source
to...

light_source { < 2, -0.5, 0 > 10*White }

Now I have enough light. Actually now I see I have multi-path problems - but
that's another thing, and I want to try and fix that myself.  I may try some
of the other suggestions to. So nice to have choice! There is a good chance
that the will be a combination that will give me just the effect I want.

I have still have some questions related to the original problem, but I'll
take your advice and ask where I can also post the image files.

Thank you once again.

Regards,
Steven

Post a reply to this message

Steven Borley wrote:
> Tim, Eero, and Alain, thank you so much.

Hey, that's what this group is for :). You're welcome.

> It has taken me some time to read through an understand your replies.  I
> didn't realise I could have light values that exceeded 1.0 - don't know but
> it just didn't occur to me.  First thing I did was to change my light source
> to...

Don't wonder, it actually took 2-3 years for me to find that out (no, I
didn't know about this newsserver back then either).

> I have still have some questions related to the original problem, but I'll
> take your advice and ask where I can also post the image files.

Like said, povray.binaries.images for the image and
povray.binaries.scene-files for the source.

> Regards,
> Steven

-- 
Eero "Aero" Ahonen
   http://www.zbxt.net
      aer### [at] removethiszbxtnetinvalid

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You need to know which kind of illumination need to increase

FIRST:
if it is the whole scene which got a lack of light ..then use
    global_setting {
            assummed_gamma 1.1  ( less is the value , lighter is your
picture) (this light up the shadows, in fact the overall scene)


    also
 if there is not enought light sources for lighting you scene , you can add
    ambient_light 2.0 for exemple (i do not recommend to use this parameter)
}

SECOND:

If you think that the amouth of light from a particular light source is not
enough the increase the color by a factor color rgb 1.2*<0.1,06,1> instead
of <0.1,0.6,1> for exemple ..(increasing the color will not light the
shadows , that will light the illuminated partof the scene and darken the
shadows.)

LAST:
if you want to light the shadow, and contrast the scene, then use the
radiosity ..


in brief you must add the following

global_settings {
    assumed_gamma 2.2 // default value
   // ambient_light rgb <0.2,0.2,0.2>   // to use at last choice
    #include "rad_def.inc"
    radiosity{Rad_Settings(Radiosity_OutdoorLQ,off,off)} // look at the
'rad_def.inc' file into your pov/include folder
}


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



news:web.4516560d8fdbbf612e23de600@news.povray.org...
> I'm new, please be kind.
>
> I have simple scene. the only source of light is from a point light source
> projecting through a slit in a wall that then falls on a prism.  I want
the
> resulting rainbow to illuminate the scene.
>
> I have the scene set up and it works nicely, except the image produced is
> too
> dark. What can I do?
>
> I cannot find any info on how to adjust the sensitivity of the camera.  I
> cannot see how to get the same effect from spot lights or other light
> sources as I need the slit shaped light source. Also, would spotlights
> actually be brighter?
>
> I would post the scene and image but I'm not allows to in this group -
> should I ask in another group?
>
> Regards,
> steven
>
>
>

Post a reply to this message

Steven Borley nous apporta ses lumieres en ce 24/09/2006 15:05:
> Tim, Eero, and Alain, thank you so much.
> 
> It has taken me some time to read through an understand your replies.  I
> didn't realise I could have light values that exceeded 1.0 - don't know but
> it just didn't occur to me.  First thing I did was to change my light source
> to...
> 
> light_source { < 2, -0.5, 0 > 10*White }
> 
> Now I have enough light. Actually now I see I have multi-path problems - but
> that's another thing, and I want to try and fix that myself.  I may try some
> of the other suggestions to. So nice to have choice! There is a good chance
> that the will be a combination that will give me just the effect I want.
> 
> I have still have some questions related to the original problem, but I'll
> take your advice and ask where I can also post the image files.
> 
> Thank you once again.
> 
> Regards,
> Steven
> 
> 
Also, a light can have a negative value like rgb -1 to shed "darkness". In fact, 
any colour can have negative values: rgb<-1,1,0> is legal and will apears as 
green. You wont see the difference in a normal scene, but it will have an effect 
on the surrounding in a radiosity scene.

-- 
Alain
-------------------------------------------------
"The way England treats her prisoners, she doesn't
  deserve to have any."               --Oscar Wilde

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