Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site unc.UUCP Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!bellcore!decvax!mcnc!unc!wfi From: wfi@unc.UUCP (William F. Ingogly) Newsgroups: net.graphics Subject: Re: Fractals Message-ID: <146@unc.UUCP> Date: Sat, 4-May-85 14:48:10 EDT Article-I.D.: unc.146 Posted: Sat May 4 14:48:10 1985 Date-Received: Mon, 6-May-85 01:02:48 EDT References: Reply-To: wfi@unc.UUCP (William F. Ingogly) Organization: CS Dept., U. of N. Carolina at Chapel Hill Lines: 35 Summary: > I am interested in building some fractal mountains. > Is there a place that I can look for some good algorithms, that > create mountains without big holes in the center? I all ready have > Mandelbrot's book. You should read "Computer Rendering of Stochastic Models," by Alain Fournier, Don Fussel, and Loren Carpenter (CACM, June 1982). This article should get you started on modelling landscapes. By the way, Mandelbrot objects STRONGLY to these models being called fractals. Other modelling techniques for natural objects that may interest you or someone else in the newsgroup: Particle systems - used for modelling the wall of fire in the Genesis effect sequence in the Star Trek movie (Star Trek II?). The reference is "Particle Systems - A Technique for Modelling a Class of Fuzzy Objects," by Bill Reeves (ACM Transactions on Graphics, April 1983). Also used by Lucasfilms and others for modelling plants. L grammars - a class of bracketed grammars that's useful for modelling branching structures like plants. The reference is "Plants, Fractals, and Formal Languages," by Alvy Ray Smith (SIGGRAPH Conference Proceedings, July 1984). You may also want to look into texture mapping, depending on the nature of your application. Simple polygonal structures can be given a highly realistic look by mapping a complex "mountain" texture onto them when they are rendered. -- Cheers, Bill Ingogly