Hi Folks,

I used photons to make mirror ball reflections, but unfortunately,
increasing the number of facets on the mirror ball didn't make more
reflected light spots, it just blurred them too much. To make this scene
look good would require several more spot lights (probably about a hundred
or so). Or maybe increasing the photon count would help - either way means
significantly increased rendering time.
--
-David

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Attachments:
Download 'Disco.jpg' (21 KB)

Preview of image 'Disco.jpg'

I recently made a disco ball image. My solution was to put every facet of
the disco ball into an array, remembering its normal, and manually calculate
the direction light would bounce off each corner of it from a given light
source, and then find the intersections of those with the floor (in your
case, with each wall, ceiling, and floor separately), drawing a box between
the four corners of the reflection with some triangles.

I resorted to this solution because I was also putting *media* in the scene,
and this made it a lot faster and more accurate than media photons did. In
your case, you may just be able to increase the number of photons, since you
have no media.

 - Slime
[ http://www.slimeland.com/ ]

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"Slime" <slm### [at] slimelandcom> wrote in message
news:3dd5c4af$1@news.povray.org...
> I recently made a disco ball image. My solution was to put every facet of
> the disco ball into an array, remembering its normal, and manually
calculate
> the direction light would bounce off each corner of it from a given light
> source, and then find the intersections of those with the floor (in your
> case, with each wall, ceiling, and floor separately), drawing a box
between
> the four corners of the reflection with some triangles.
>
> I resorted to this solution because I was also putting *media* in the
scene,
> and this made it a lot faster and more accurate than media photons did. In
> your case, you may just be able to increase the number of photons, since
you
> have no media.

See if you can tell how I created this effect...
http://home.mindspring.com/~grasshoppah/Disco.jpg

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> See if you can tell how I created this effect...
> http://home.mindspring.com/~grasshoppah/Disco.jpg
>

Well, my first thought was: whats a disco ball without a disco?


...groovy
-Ive

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Hey cool!

Actually, I was gonna do this... (I'm currently working on an animation of
some flashing disco lights with media. Might even post it one day!)

Andrew.

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Slime wrote:

> I recently made a disco ball image. My solution was to put every facet of
> the disco ball into an array, remembering its normal, and manually
> calculate the direction light would bounce off each corner of it from a
> given light source, and then find the intersections of those with the
> floor (in your case, with each wall, ceiling, and floor separately),
> drawing a box between the four corners of the reflection with some
> triangles.
> 
> I resorted to this solution because I was also putting *media* in the
> scene, and this made it a lot faster and more accurate than media photons
> did. In your case, you may just be able to increase the number of photons,
> since you have no media.

I used a similar approach for my disco ball. However, I simply put spot
lights next to the surface of the disco ball. This saves you from using
an array. An image, a short animation and source can be found in my
raytracing gallery at http://www.grafik.willhalm.de/ . Be aware that the
scene was written for povray 3.0 (or was it 3.1?).

Thomas

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Thomas Willhalm wrote:
> 
> Slime wrote:
> 
> > I recently made a disco ball image. My solution was to put every facet of
> > the disco ball into an array, remembering its normal, and manually
> > calculate the direction light would bounce off each corner of it from a
> > given light source, and then find the intersections of those with the
> > floor (in your case, with each wall, ceiling, and floor separately),
> > drawing a box between the four corners of the reflection with some
> > triangles.
> >
> > I resorted to this solution because I was also putting *media* in the
> > scene, and this made it a lot faster and more accurate than media photons
> > did. In your case, you may just be able to increase the number of photons,
> > since you have no media.
> 
> I used a similar approach for my disco ball. However, I simply put spot
> lights next to the surface of the disco ball. This saves you from using
> an array. An image, a short animation and source can be found in my
> raytracing gallery at http://www.grafik.willhalm.de/ . Be aware that the
> scene was written for povray 3.0 (or was it 3.1?).
> 
> Thomas

Hello Thomas,
Thank you for your marvellous images and for putting the source
available to other people, learning how to use Povray.
-- 
Herman Serras
Gent (Belgium)
http://cage.rug.ac.be/~hs/

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In article <3dd8b526@news.povray.org>,
 Thomas Willhalm <tho### [at] uni-konstanzde> wrote:

> I used a similar approach for my disco ball. However, I simply put spot
> lights next to the surface of the disco ball. This saves you from using
> an array. An image, a short animation and source can be found in my
> raytracing gallery at http://www.grafik.willhalm.de/ . Be aware that the
> scene was written for povray 3.0 (or was it 3.1?).

A more 3.5 way of doing it would probably be to use projected_through to 
get the spotlights to have square outlines. This technique would have 
less overhead than photons, but only works for flat mirrors.

-- 
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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On Fri, 15 Nov 2002 19:05:57 -0800, Dave Blandston wrote:
> Hi Folks,
> 
> I used photons to make mirror ball reflections, but unfortunately,
> increasing the number of facets on the mirror ball didn't make more
> reflected light spots, it just blurred them too much. To make this scene
> look good would require several more spot lights (probably about a hundred
> or so). Or maybe increasing the photon count would help - either way means
> significantly increased rendering time.
> --

I did one ages ago, not all that complicated, but does exactly what you're
after. 

http://www.zeropps.uklinux.net/gallery.html

It renders quite fast, fast enough for me to make a fifteen second 
animation of the ball soing a twirl in various directions and coming back
to it's original state, it looks great when you loop the animation and 
play music and turn the lights off in the room, my own private disco. 


-- 
sphere{z*5,1pigment{rgb.5}finish{reflection.3specular.5}}box{<-50,-3,-50>
<50,-2,50>pigment{checker/*\__\\__/  * \_\\__*/scale 2}finish{ambient.7}}
light_source/*__\\__\\__\\__\\__\(    ~ )\__\\__\\__\\__\\*/{<2,5,1>*4,1} 
/*\\__\\__\\__\\__\\__\\__\\__\\__\~  -/__\\__\\__\\__\\__\\*//* Steve */

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