The code for this image is by Manuel Kasten, who posted it in
povray.general.

The strange attractor is iterated 2 million times.

This rendering was done entirely in POV using a machine with 384Mb of
memory.

There are 207620 spheres in the image.

Instead of adding a new sphere for each iteration of the strange attractor,
if there already was a sphere at a point I just changed its pigment to make
it brighter. Some spheres have had their pigment brightened 161 times which
gives them a pigment of about {rgb 5}. I had to make the brightening so
strong because the vast majority of spheres only get brigtened a few times
and when I tried creating output in teh range {rgb 0} to {rgb 1} most of
them were nearly black.

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Attachments:
Download 'StrangeA2.jpg' (75 KB)

Preview of image 'StrangeA2.jpg'

Mike Williams wrote:

> Instead of adding a new sphere for each iteration of the strange attractor,
> if there already was a sphere at a point I just changed its pigment to make
> it brighter. 

You added a "measure."  Nice!

How did you decide whether there already was a sphere at a point?  I 
mean, what did the POV code look like for that?  I've been trying to do 
this, but my solutions are always very inefficient.  I'm guessing that 
you store the locations in an array and compare (?)

Thanks

Dave Matthews

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Among other things, Dave Matthews wrote:

> How did you decide whether there already was a sphere at a point?  I
> mean, what did the POV code look like for that?  I've been trying to do
> this, but my solutions are always very inefficient.  I'm guessing that
> you store the locations in an array and compare (?)

Maybe test for "inside-ness" against a union of all spheres?

-- 
light_source{9+9*x,1}camera{orthographic look_at(1-y)/4angle 30location
9/4-z*4}light_source{-9*z,1}union{box{.9-z.1+x clipped_by{plane{2+y-4*x
0}}}box{z-y-.1.1+z}box{-.1.1+x}box{.1z-.1}pigment{rgb<.8.2,1>}}//Jellby

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Wasn't it Dave Matthews who wrote:
>
>
>Mike Williams wrote:
>
>> Instead of adding a new sphere for each iteration of the strange attractor,
>> if there already was a sphere at a point I just changed its pigment to make
>> it brighter. 
>
>You added a "measure."  Nice!
>
>How did you decide whether there already was a sphere at a point?  I 
>mean, what did the POV code look like for that?  I've been trying to do 
>this, but my solutions are always very inefficient.  I'm guessing that 
>you store the locations in an array and compare (?)
>

Yes. I accumulated the brightnesses in an array and then only created
spheres where the brightness was non-zero. It wasn't particularly
efficient. 2h 47m 59s on a 850MHz Celeron.

-- 
Mike Williams
Gentleman of Leisure

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Mike Williams wrote:

> Yes. I accumulated the brightnesses in an array and then only created
> spheres where the brightness was non-zero. It wasn't particularly
> efficient. 2h 47m 59s on a 850MHz Celeron.
> 

Thanks.  That's still a big improvement over my methods.  I was creating 
the spheres, storing each location in an array, then running a new 
comparison each time to see whether I already had a sphere. . . . I 
still don't think enough like a programmer.

Well, now I can give it a go on a 3D IFS and see what comes out.

Thanks again!

Dave Matthews

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