I'm trying to use a spotlight, and getting some results that aren't what 
I expected.  Please forgive me for dropping a code fragment in here...

	light_source {
		<0, -3.4515, -1.701>
		color White
		spotlight
		radius 40
		falloff 60
		tightness 0
		point_at <0, -3.1989, -60>
		}

I expected to see a cone of illumination along the surface of my 
model... and I did, sort of... but the intensity of the light was much 
lower than I expected, and instead of reaching all the way to the 
point_at location, it faded within ten units of the source.

Can someone suggest how to turn up the intensity?

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In article <3D5### [at] maccom>, Dawn McKnight <blu### [at] maccom> 
wrote:

> I expected to see a cone of illumination along the surface of my 
> model... and I did, sort of... but the intensity of the light was much 
> lower than I expected, and instead of reaching all the way to the 
> point_at location, it faded within ten units of the source.

Probably due to the angle of the surface to the light direction. You 
could lower the brilliance value of the surface finish, but that will 
affect all shading of that surface.


> Can someone suggest how to turn up the intensity?

Specify a brighter color for the light source. Values > 1 are perfectly 
acceptable, they will just wash things out in some cases. You can even 
specify negative values, though that isn't realistic.

-- 
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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> Probably due to the angle of the surface to the light direction. You 
> could lower the brilliance value of the surface finish, but that will 
> affect all shading of that surface.

You're saying that the angle is too acute?  At what zenith range do 
spotlights work best?

Thanks for the information about values greater than one... I'll try it.

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In article <3D5### [at] maccom>,
 Dawn McKnight <blu### [at] maccom> wrote:

> > Probably due to the angle of the surface to the light direction. You 
> > could lower the brilliance value of the surface finish, but that will 
> > affect all shading of that surface.
> 
> You're saying that the angle is too acute?  At what zenith range do 
> spotlights work best?

Wrong question. Any light will light a surface most brightly when its 
direction is perpendicular to the surface, parallel to the surface 
normal. Your description makes it sound like the light is very nearly 
parallel to the surface, so shading will make it dimmer. It isn't that 
the spotlight isn't working right, it is doing exactly what it should.
Another possibility is that the point_at location is inside the shape, 
or otherwise positioned to make the light get blocked by the shape. You 
only gave an example of the spotlight, so I can't really say. Try a 
point light and see how the surface gets illuminated. If that fixes the 
problem, there is something wrong with the point_at, radius, or falloff.

-- 
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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Christopher James Huff <chr### [at] maccom> wrote:
> Any light will light a surface most brightly when its 
> direction is perpendicular to the surface, parallel to the surface 
> normal.

  Only with diffuse lighting. Specular lighting (controlled with the
phong or specular keywords in finish) is another story. :)

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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> Any light will light a surface most brightly when its 
> direction is perpendicular to the surface, parallel to the surface 
> normal. Your description makes it sound like the light is very nearly 
> parallel to the surface, so shading will make it dimmer.

Okay; thanks.  I played around with it, and found a way to get the 
effect I wanted, by faking it... putting an aparent light source (a 
sphere with a high ambient, low diffuse finish), and then putting the 
actual spotlight further out from wht I'm trying to illuminate.

It looks about right, and I feel less 'wrong' about doing it that way, 
because I know that all of the spotlights on the Movie Enterprises were 
faked with off-model pin sources.

So, yeah... thanks again, Christopher.

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