On Fri, 19 Nov 1999 00:07:31 -0600, "michael mcknight" <nes### [at] ouedu>
wrote:

>i posted earlier saying that i get an error in julia fractals sometimes that
>looks like parts of them have been randomly sliced up.  i got a reply, which
>i was most grateful for, saying that the putting the camera inside the
>bounding sphere of the julia fractal was causing the error.  unfortunately,
>when i moved it back to 20 units, i still get the error.  does anyone one
>know why?  thanks in advance.  

Michael,

sorry I mislead you. The problem I pointed out was the most common one
that I had with julias in the past. What you are facing now is a
completely different situation. It is definitely an algorithm flaw.

Change your scene file to this:

camera{
  location <0,0,-23>
  angle 7
  look_at 0
}

light_source{
  <100,100,-1000>
  color rgb 1
}

julia_fractal{ 
  <-1.154166666666666, -0.25, 0, 0>
  max_iteration 4
  quaternion
  sqr   
  precision 200
  pigment{rgb <1,.3,.3>}
  rotate<0,50,0>
  no_shadow
} 


And your command-line settings to this:

+sc0.839063 +sr0.354167 +ec0.959375 +er0.522917 +w4000 +h3000 -a

Notice how the problem starts right where the back, err, edge of the
fractal ends? Like a max_trace_level problem, but vice-versa? It
definitely looks like a ray-shape intersection flaw. The Julia root
finder should work fine, I just can't imagine what drives it nuts in
this case. Sorry, I can't help more without digging into the code
(which I will do now, but it will probably help nothing).

I will try to contact Pascal Massimino and see if he knows more on the
subject. And yeah, I know he's not a Team member anymore.

With that said... well, try to find other beautiful fractals that are



Peter Popov
ICQ: 15002700

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