Hello again.
Time to end the html flame, at least in my opininon..
So I thought I'd get RTFM'd a bit..
Can someone explain the _uses_ of a cylinder light ???

//Spider

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In article <36B22DC2.CB2DC8D3@bahnhof.se> , Spider <spi### [at] bahnhofse>  wrote:

> Can someone explain the _uses_ of a cylinder light ???

Hmm, maybe it would make a good laser?


    Thorsten

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Well, a cylinder light is simply a spotlight constrained by a cylinder, instead of
a cone like regualt spotlights... and the docs do suggest that they make good
lasers... what I don't understand,and hopefully some one can explain it... is how
does POV-Ray determine the size of the cylinder that constrains the light?

Josh English
eng### [at] spiritonecom

Thorsten Froehlich wrote:

> In article <36B22DC2.CB2DC8D3@bahnhof.se> , Spider <spi### [at] bahnhofse>  wrote:
>
> > Can someone explain the _uses_ of a cylinder light ???
>
> Hmm, maybe it would make a good laser?
>
>     Thorsten

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Great for downlights (where you need to light an area evenly), excellent
directional lights, backlighting (turn shadows off), search lights (where
the beam starts wide, not from a point), lasers, energy "beams" (use with
media).  One of my favourites is lighting up a glass cylinder from below (so
it's constrained to the cylinder) and then difference spheres out of the
cylinder to make it look like bubbles (they light up in it).  A luxo :-)
Once again, a lot of desklights have cylinder beams rather than spotlight
beams because the light reflects so much around the inside that it has an
even downspread rather than starting from a point.  It's often good to use
cylinder lights for getting a secular highlight on the side of an object to
emphasise the edge.

Check out
http://www.fortunecity.com/skyscraper/parallax/359/max_steel_zephyr.jpg for
an example where I used a lot of cylinder lights (especially the back blue
area which was created solely by a cylinder light).  The upper sphere (which
is surprisingly only seen in the bottom of the image) was also lit by a
cylinder light to light the sphere evenly along one side (that sphere is
BIG).

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

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Thankyou for the information... 
I must say that the image was very interesting, and that I know understand some of the
uses of the cylinder light... Thanx again!
//Spider

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That's OK, and I just thought of another one, like in Stargate, a matter
transfer portal!!! :)

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone

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Lance Birch wrote in message <36b26c17.0@news.povray.org>...
>That's OK, and I just thought of another one, like in Stargate, a matter
>transfer portal!!! :)
>
>--
>Lance.
>
How about an activated lightsabre?
>
>---
>For the latest 3D Studio MAX plug-ins, images and much more, go to:
>The Zone - http://come.to/the.zone
>
>

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Didn't see a mention of working with the size of these.
I don't know any formula to it or anything, but the diameter is trickier
than regular conical spotlights from what I've seen.
The radius needs to be pretty high if you want coverage of an area where
the cylinder points to. Tightness makes a big difference too.
No matter what though the two types do not equal their illumination of
area. Spotlight can vary intensity from full to fading over any area and
cylinder lights remain constrained to a central point which varies
outward in size yet doesn't reach full intensity over the entire radius.

Following is a comparison:

//BEGIN
// approx. 4 X 3 window at 0*z
camera
{
  location  <0.0 , 0.0 ,-9.0>
  direction 3*z
  look_at   <0.0 , 0.0 , 0.0>
}

// create a point "spotlight" (conical/directed) light source
light_source
{
  -10*z
  color rgb 1
  spotlight
  point_at <0, 0, 0>
  radius 1
  tightness 10
  falloff 10
  translate -1.5*x
}

// create an area "spotlight" (cylindrical/directed) light source
light_source
{
  -10*z
  color rgb 1
  spotlight
  cylinder
  point_at <0, 0, 0>
  radius 50     // larger numbers required to equal area spot
  tightness 50 // smaller numbers here to expand, larger to shrink
  falloff 50  // notice radius and falloff never merge
  translate 1.5*x
}

plane {z,0 pigment {rgb 1}}
//END


Spider wrote:
> 
> Hello again.
> Time to end the html flame, at least in my opininon..
> So I thought I'd get RTFM'd a bit..
> Can someone explain the _uses_ of a cylinder light ???
> 
> //Spider

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.htm
=Bob

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Bob Hughes wrote:
> 
> Didn't see a mention of working with the size of these.
> I don't know any formula to it or anything, but the diameter is trickier
> than regular conical spotlights from what I've seen.
> The radius needs to be pretty high if you want coverage of an area where
> the cylinder points to. Tightness makes a big difference too.
> No matter what though the two types do not equal their illumination of
> area. Spotlight can vary intensity from full to fading over any area and
> cylinder lights remain constrained to a central point which varies
> outward in size yet doesn't reach full intensity over the entire radius.
Thank you!
I'll work with it!

I must say, I really appreciate the help one gets around here, thank you all !

//Spider

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Lue Ebra wrote:
> 
> How about an activated lightsabre?

Yeah, to cut the HTML off ;-)

SCNR.

Markus
-- 

 Ich nicht eine Sekunde!!!" H. Heinol in Val Thorens

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