bungi@milton.u.washington.edu (Timothy J. Wood) (04/30/91)
I've seen some discussion about the rendering of 3-d slices of various 4-d fractals (esp, M and J_c), but I have yet to find any source code for such creatures. Is there any out there available for ftp, or does anyone have any source they would mail me? Failing this, does anyone know a fairly accurate method for computing the a normal to a procedurally defined surface (in this case M or J_c)? Assuming I don't receive any source, what suggestions would you have for implementing a distributed fractal ray-tracer? Who would like a copy when i'm done? (I know I'll get a response from this one... :)
rdb@ktibv.uucp (Rob den Braasem) (05/01/91)
bungi@milton.u.washington.edu (Timothy J. Wood) writes: > I've seen some discussion about the rendering of 3-d slices of various >4-d fractals (esp, M and J_c), but I have yet to find any source code for > Assuming I don't receive any source, what suggestions would you have for >implementing a distributed fractal ray-tracer? Who would like a copy when >i'm done? (I know I'll get a response from this one... :) Hallo tim, I once saw on british television a four dimentional walk through a three dimentional representation of a four dimentional fractal. ( got the dimentions right :))) But serious. Try to get a hold of SIGGRAPH '89. There was an artical in it from Hart, Sandin and Kauffman about raytracing fractals. I sure would like to have a copy if your ready. Happy Hacking "PABRAS" "The Graphical Gnome" ----------------------------------------------------------------------------- | Rob den Braasem | "Before I sink into the big | Voice :-31-79-531825 | | | sleep, I want to hear the | Fax :-31-79-513561 | | | scream of the butterfly." | Mail : | | "PABRAS" | J. Morrison | ....!hp4nl!ktibv!rdb | | KTI bv |-------------------------------| ---------------------| | P.O. Box 86 | " We got to get out of this place, even if it is the | | 2700 AB Zoetermeer | last thing we will ever do. " | | The Netherlands | CCR | ----------------------------------------------------------------------------- -- Happy Hacking "PABRAS" ----------------------------------------------------------------------------- | Rob den Braasem | "Before I sink into the big | Voice :-31-79-531825 |
chrisg@cbmvax.commodore.com (Chris Green) (05/01/91)
In article <1991Apr30.074427.29894@milton.u.washington.edu> bungi@u.washington.edu writes: > > I've seen some discussion about the rendering of 3-d slices of various >4-d fractals (esp, M and J_c), but I have yet to find any source code for >such creatures. Is there any out there available for ftp, or does anyone >have any source they would mail me? > > Failing this, does anyone know a fairly accurate method for computing >the a normal to a procedurally defined surface (in this case M or J_c)? > > Assuming I don't receive any source, what suggestions would you have for >implementing a distributed fractal ray-tracer? Who would like a copy when >i'm done? (I know I'll get a response from this one... :) I posted Forth souce code for this in alt.fractals a while back. -- *-------------------------------------------*---------------------------* |Chris Green - Graphics Software Engineer - chrisg@commodore.COM f | Commodore-Amiga - uunet!cbmvax!chrisg n |My opinions are my own, and do not - killyouridolssonicdeath o |necessarily represent those of my employer.- itstheendoftheworld r *-------------------------------------------*---------------------------d
kaufman@eecs.nwu.edu (Michael L. Kaufman) (05/02/91)
bungi@milton.u.washington.edu (Timothy J. Wood) writes: > Assuming I don't receive any source, what suggestions would you have for >implementing a distributed fractal ray-tracer? I would suggest that you go to Siggraph this year and take course C14 on tuesday (Fractal Modeling in 3d Computer Graphics and Modeling). There are quite a few interesting courses this year. I had a tough time narrowing it down to only two. Michael -- Michael Kaufman | I've seen things you people wouldn't believe. Attack ships on kaufman | fire off the shoulder of Orion. I watched C-beams glitter in @eecs.nwu.edu | the dark near the Tannhauser gate. All those moments will be | lost in time - like tears in rain. Time to die. Roy Batty
will@rins.ryukoku.ac.jp (will) (05/02/91)
Take a look at the book Fractal Programming and Ray Tracing with C++,
by Roger T. Stevens. ISBN: 1-55851-118-0. On the back, it says that
it provides info on the techniques of interweaving fractals and ray-
tracing. I have'nt read it yet. So, I really can only say take a look
at it.
William Dee Rieken
Researcher, Computer Visualization
Faculty of Science and Technology
Ryukoku University
Seta, Otsu 520-21,
Japan
Tel: 0775-43-7418(direct)
Fax: 0775-43-7749
will@rins.ryukoku.ac.jpxanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) (05/03/91)
> bungi@u.washington.edu writes: > Failing this, does anyone know a fairly accurate method for computing > the a normal to a procedurally defined surface (in this case M or > J_c)? Which brought to mind this sudden realization: the boundary of a fractal object like a snowflake curve or the Mandelbrot set, being everywhere of discontinuous first derivative (in the > 2D case, Jacobian), what in the world does one intend when one says the "normal" to such an object at a particular point? Does one limit resolution, do some local smoothing, and take the normal to the resultant bounding surface? Most of the interesting rendering algorithms I know misbehave at surface derivative discontinuities; how in the world does one proceed when the surface derivative is everywhere discontinuous? Kent, the man from xanth. <xanthian@Zorch.SF-Bay.ORG> <xanthian@well.sf.ca.us>
bungi@milton.u.washington.edu (Timothy J. Wood) (05/04/91)
In article <1991May3.085302.18527@zorch.SF-Bay.ORG> xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes: >> bungi@u.washington.edu writes: > >> Failing this, does anyone know a fairly accurate method for computing >> the a normal to a procedurally defined surface (in this case M or >> J_c)? > >... what in the >world does one intend when one says the "normal" to such an object at a >particular point? > >Does one limit resolution, do some local smoothing, and take the normal >to the resultant bounding surface? > The method i'm using is an approximation based on the gradient of the distance estimator function d(z) presented in 'The Science of Fractal Images' (Peitgen). One can also use the gradient of the potential function G(z) (from the same source). -- ------------------------------------------------------------------------------- Timothy Wood : bungi@u.washington.edu, tjwood@cs.washington.edu ... alice everyday brings sunshine ...
cloister@milton.u.washington.edu (cloister bell) (05/04/91)
bungi@milton.u.washington.edu (Timothy J. Wood) writes: >In article <1991May3.085302.18527@zorch.SF-Bay.ORG> xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes: >> >>Does one limit resolution, do some local smoothing, and take the normal >>to the resultant bounding surface? >> > The method i'm using is an approximation based on the gradient of the >distance estimator function d(z) presented in 'The Science of Fractal >Images' (Peitgen). One can also use the gradient of the potential function >G(z) (from the same source). which to me seems a valid method. the whole idea behind ray tracing is to simulate what happens to light rays when they hit things. when a light ray hits a fractal object (if there were such things in the real world) since the scale of the features on the surface will be (because it's a fractal) smaller than the wavelength of the photon that hits it. recalling my physics classes of several years ago, when this sort of things happens, the photon is going to bounce in ways related to the average (i.e. 'macroscopic' in whatever sense that word applies to photons) gradient of the surface. best of luck, mr. wood. -- +-------------------------------------------------+---------------------------+ |i thought of a good sig, but it was a sight gag. | cloister@u.washington.edu | +-------------------------------------------------+---------------------------+