"Danny" <danzaetz> wrote:
> Alain <aze### [at] qwertygov> wrote:
> > Danny nous apporta ses lumieres ainsi en ce 2004/05/18 15:08... :
> >
> > >"Danny" <danzaetz> wrote:
> > >
> > >
> > >>Alain <aze### [at] qwertygov> wrote:
> > >>
> > >>
> > >>>Danny nous apporta ses lumieres ainsi en ce 2004/05/17 16:39... :
> > >>>
> > >>>
> > >>>
> > >>>>Alain <aze### [at] qwertygov> wrote:
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>>>Danny nous apporta ses lumieres ainsi en ce 2004/05/17 05:23... :
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>>>Alain <aze### [at] qwertygov> wrote:
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>I used exactly what you told me, and I got a cylinder with white edges that
> > >>>>>>fades to nothing in the middle (without any red at all), and even those
> > >>>>>>white edges disappear as the cylinder continues on.  I'm using POV-Ray 3.5,
> > >>>>>>and here is the code I used:
> > >>>>>>
> > >>>>>>cylinder{<100,0,0>,<0,0,0>, .20
> > >>>>>>       texture {
> > >>>>>>  pigment { color rgbt 1}
> > >>>>>>  finish{reflection 0}}
> > >>>>>>     interior{media{emission rgb 1
> > >>>>>>     density{ cylindrical
> > >>>>>>     color_map{[0 rgb 0][0.5 rgb<1,0,0>][0.98 rgb 1][1 rgb 2]}
> > >>>>>>     }}}
> > >>>>>>     hollow
> > >>>>>>     translate<0,0,2>
> > >>>>>>     }
> > >>>>>>
> > >>>>>>Can you tell me what I'm doing wrong, and how to fix it?
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>Set the radius of the cylinder to 1, then rescale it by scale<.2,1,.2>
> > >>>>>just before you rotate it.
> > >>>>>You don't need to set finish{reflection 0}}, it's the default value.
> > >>>>>Set your cylinder verticaly, as it's the orientation of the cylindrical
> > >>>>>pattern, then rotate the whole thing.
> > >>>>>...
> > >>>>>scale<0.2, 1, 0.2>
> > >>>>>rotate -90*z
> > >>>>>translate<0, 0, 2>
> > >>>>>}// that's the last brace
> > >>>>>
> > >>>>>Alain
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>OK, now it looks good when I don't scale it, but scaling it seems to mess it
> > >>>>up.
> > >>>>When I scale it up it still seems to look OK, except the inner white part
> > >>>>has become enlarged disproportionately.  But when I scale it down, I lose
> > >>>>the white part completely, and all I have is a very dimly red cylinder.
> > >>>>Can you explain why it's doing this and how I can make it scale down right?
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>Try lowering the 0.98 to a smaler value, thus enlarging the central
> > >>>part. As it is now, the white center part only have a radius of 0.02
> > >>>units and may disappears when scaled down or if the image is generated
> > >>>at a low resolution.
> > >>>Don't scale only the media but the whole cylinder containing the media.
> > >>>
> > >>>Alain
> > >>>
> > >>>
> > >>Thanks a lot for all your help!  I managed to fix the scaling problem by
> > >>multiplying the brightness of all the color map values by 5.  I guess this
> > >>is because there is less matter in the media to show up if I scale it down
> > >>to a fifth of its size.
> > >>
> > >>
> > Good guess
> >
> > >>Thanks,
> > >>Danny
> > >>
> > >>
> > >
> > >I've got another problem. For some strange reason, my media cylinder is
> > >acting like a convex lens. It's showing an narrowed image on the right side
> > >of the cylinder of an object behind and to the left of it.  It's refracting
> > >(not reflecting) light, I think.  When I zoom out, it looks like ugly white
> > >lines on the side of my laser. How do I get rid of them?
> > >
> > >Danny
> > >
> > >
> > >
> > With emissive only media, the beam is effectively transparent, that is,
> > you see anything that may be behind. That was (barely) visible in the
> > small sample as a slight discontuity near the middle of the image. You
> > may want to add some absorbtion and/or scattering, it's not realistic as
> > the beam is only light, but may be more aestetic.
> >
> > Alain
>
> Neither the absorption nor any of the scatterings are able to get rid of the
> image.  It's odd.  It's not like the stars I have in the distance, which
> are right behind the the laser and are completely visible through the
> laser.  The object is not directly behind the laser, it's back and to the
> left, and not obstructed by the laser at all, but it's projecting a thinned
> and flipped image of itself on the right side of the laser.  Have you seen
> anything like this?

I still can't figure out how to get rid of the images on the surface of the
laser.  Please help.

Danny

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