kjartan@raunvis.UUCP (Kjartan Pierre Emilsson Jardedlisfraedi) (12/22/88)
Has anyone had any experience with the application of ray-tracing techniques to simulate accoustics, i.e the formal equivalent of ray-tracing using sound instead of light. Can a ray-tracing algorithm be easily adapted to sound tracing. How important are secondary rays, and how good is the simulation using only first and second generation rays ? -Kjartan & Dagur -------------------------------------------------------------------------- Kjartan Pierre Emilsson Science Institute - University of Iceland Dunhaga 3 107 Reykjavik Iceland Internet: kjartan@raunvis.hi.is
rsb584@leah.Albany.Edu (Raymond S Brand) (12/23/88)
In article <239@raunvis.UUCP>, kjartan@raunvis.UUCP (Kjartan Pierre Emilsson Jardedlisfraedi) writes: > > Has anyone had any experience with the application of ray-tracing techniques to > simulate accoustics, i.e the formal equivalent of ray-tracing using sound instead > of light. Can a ray-tracing algorithm be easily adapted to sound tracing. How > important are secondary rays, and how good is the simulation using only first and > second generation rays ? > -------------------------------------------------------------------------- > Kjartan Pierre Emilsson > Science Institute - University of Iceland > Dunhaga 3 > 107 Reykjavik > Iceland Internet: kjartan@raunvis.hi.is A friend and I talked about doing this abaout a year ago but nothing came of it. Some thoughts though, radiosity would probably work better than ray-tracing. You will need to deal with phase relationships of the sound energy. It isn't clear what is needed to model the reflecting surfaces (at least to me). How do display the results? ------------------------------------------------------------------------- Raymond S. Brand rsbx@beowulf.uucp 3A Pinehurst Ave. rsb584@leah.albany.edu Albany NY 12203 FidoNet 1:7729/255 (518-489-8968) (518)-482-8798 BBS: (518)-489-8986
ph@miro.Berkeley.EDU (Paul Heckbert) (12/24/88)
In article <239@raunvis.UUCP> kjartan@raunvis.UUCP (Kjartan Pierre Emilsson Jardedlisfraedi) asks: > Has anyone had any experience with the application of ray-tracing techniques > to simulate accoustics, i.e the formal equivalent of ray-tracing using sound > instead of light? ... Yes, John Walsh, Norm Dadoun, and others at the University of British Columbia have used ray tracing-like techniques to simulate acoustics. They called their method of tracing polygonal cones through a scene "beam tracing" (even before Pat Hanrahan and I independently coined the term for graphics applications). Walsh et al simulated the reflection and diffraction of sound, and were able to digitally process an audio recording to simulate room acoustics to aid in concert hall design. This is my (four year old) bibliography of their papers: %A Norm Dadoun %A David G. Kirkpatrick %A John P. Walsh %T Hierarchical Approaches to Hidden Surface Intersection Testing %J Proceedings of Graphics Interface '82 %D May 1982 %P 49-56 %Z hierarchical convex hull or minimal bounding box to optimize intersection testing between beams and polyhedra, for graphics and acoustical analysis %K bounding volume, acoustics, intersection testing %A John P. Walsh %A Norm Dadoun %T The Design and Development of Godot: A System for Room Acoustics Modeling and Simulation %B 101st meeting of the Acoustical Society of America %C Ottawa %D May 1981 %A John P. Walsh %A Norm Dadoun %T What Are We Waiting for? The Development of Godot, II %B 103rd meeting of the Acoustical Society of America %C Chicago %D Apr. 1982 %K beam tracing, acoustics %A John P. Walsh %T The Simulation of Directional Sound Sources in Rooms by Means of a Digital Computer %R M. Mus. Thesis %I U. of Western Ontario %C London, Canada %D Fall 1979 %K acoustics %A John P. Walsh %T The Design of Godot: A System for Room Acoustics Modeling and Simulation, paper E15.3 %B Proc. 10th International Congress on Acoustics %C Sydney %D July 1980 %A John P. Walsh %A Marcel T. Rivard %T Signal Processing Aspects of Godot: A System for Computer-Aided Room Acoustics Modeling and Simulation %B 72nd Convention of the Audio Engineering Society %C Anaheim, CA %D Oct. 1982 Paul Heckbert, CS grad student 508-7 Evans Hall, UC Berkeley UUCP: ucbvax!miro.berkeley.edu!ph Berkeley, CA 94720 ARPA: ph@miro.berkeley.edu
elf@dgp.toronto.edu (Eugene Fiume) (12/24/88)
In article <239@raunvis.UUCP> kjartan@raunvis.UUCP (Kjartan Pierre Emilsson Jardedlisfraedi) writes [reformatted]: > Has anyone had any experience with the application of ray-tracing > techniques to simulate accoustics, i.e the formal equivalent of > ray-tracing using sound instead of light. Can a ray-tracing algorithm > be easily adapted to sound tracing. How important are secondary rays, > and how good is the simulation using only first and second generation > rays ? I distinctly recall that Prof. David Kirkpatrick and a student of his were working on precisely this problem a couple of years back. They are at the University of British Columbia. My e-mail address for him may be dated. Try one of kirk@[cs.ubc.ca | ubc-cs.uucp | ubc-cs!ubc-vision]. Is there a UBC'er who can give a better address? -- Eugene Fiume Dynamic Graphics Project University of Toronto elf@dgp.toronto.edu
jevans@.ucalgary.ca (David Jevans) (12/27/88)
Three of my friends did a sound tracer for an undergraduate project last year.
The system used directional sound sources and microphones and a ray-tracing-like
algorithm to trace the sound. Sound sources were digitized and stored in files.
Emitters used these sound files. At the end of the 4 month project
they could digitize something, like a person speaking, run it through the
system, then pump the results through a speaker. An acoustic environment
was built (just like you build a model for graphics). You could get
effects like echoes and such. Unfortunately this was never published.
I am trying to convince them to work on it next semester...
David Jevans, U of Calgary Computer Science, Calgary AB T2N 1N4 Canada
uucp: ...{ubc-cs,utai,alberta}!calgary!jevanseugene@eos.UUCP (Eugene Miya) (12/29/88)
May I also add that you research all the work on accoustic
lasers done at places like the Applied Physics Lab.
Another gross generalization from
--eugene miya, NASA Ames Research Center, eugene@aurora.arc.nasa.gov
resident cynic at the Rock of Ages Home for Retired Hackers:
"Mailers?! HA!", "If my mail does not reach you, please accept my apology."
{uunet,hplabs,ncar,decwrl,allegra,tektronix}!ames!aurora!eugene
"Send mail, avoid follow-ups. If enough, I'll summarize."kjartan@raunvis.UUCP (Kjartan Pierre Emilsson Jardedlisfraedi) (12/30/88)
Hi, We would like to begin by thanking everybody for their good replies, which will in no doubt come handy. We intend to try to implement such a sound tracer soon and we had already made some sort of model for it, but we were checking wether there was some info lying around about such tracers. It seems that our idea wasn't far from actual implementations and that is reassuring. For the sake of Academical Curiosity and overall Rennaisance-like Enlightnment in the beginning of a new year we decided to submit our crude model to the critics and attention of this newsgroup, hoping that it won't interfere too much with the actual subject of the group, namely computer graphics. The Model: We have some volume with an arbitrary geometry (usually simple such as a concert hall or something like that). Squares would work just fine as primitives. Each primitive has definite reflection properties in addition to some absorbtion filter which possibly filters out some frequencies and attenuates the signal. In this volume we put a sound emitter which has the following form: The sound emitter generates a sound sample in the form of a time series with a definite mean power P. The emitter emits the sound with a given power density given as some spherical distribution. For simplicity we tesselate this distribution and assign to each patch the corresponding mean power. At some other point we place the sound receptor which has the following form: We take a sphere and cut it in two equal halves, and then seperate the two by some distance d. We then tesselate the half-spheres (not including the cut). We have then a crude model of ears. Now for the actual sound tracing we do the following: For each patch of the two half-spheres, we cast a ray radially from the center, and calculate an intersection point with the enclosing volume. From that point we determine which patch of the emitter this corresponds to, giving us the emitted power. We then pass the corresponding time series through the filter appropriate to the given primitives, calculate the reflected fraction, attenuate the signal by the square of the distance, and eventually determine the delay of the signal. When all patches have been traced, we sum up all the time series and output the whole lot through some stereo device. A more sophisticated model would include secondary rays and sound 'shadowing' (The shadowing being a little tricky as it is frequency dependent) pros & cons ? Happy New Year !! -Kjartan & Dagur -------------------------------------------------------------------------- Kjartan Pierre Emilsson Science Institute - University of Iceland Dunhaga 3 107 Reykjavik Iceland Internet: kjartan@raunvis.hi.is
ksbooth@watcgl.waterloo.edu (Kelly Booth) (12/30/88)
We are being flooded by a lot of amateur postings about ray tracing for sound. This is not a new idea and it is not a new topic. Most of the postings appear to be quite naive approaches. There are commercial companies that have applied computer techniques to problems in acoustics for many years. There are big bucks to be made in this field. It is highly unlikely that a couple of hackers thinking about the problem for a few minutes will generate startling break throughs (possible, but not likely). It would be nice to see just a few postings with references to the classical references in the field. After these have been explored, the net is a good place to make comments and to further discuss nuances not covered in standard books or journals.
markv@uoregon.uoregon.edu (Mark VandeWettering) (12/31/88)
In article <7488@watcgl.waterloo.edu> ksbooth@watcgl.waterloo.edu (Kelly Booth) writes: >We are being flooded by a lot of amateur postings about ray tracing for >sound. This is not a new idea and it is not a new topic. Most of the >postings appear to be quite naive approaches. There are commercial >companies that have applied computer techniques to problems in >acoustics for many years. There are big bucks to be made in this >field. It is highly unlikely that a couple of hackers thinking about >the problem for a few minutes will generate startling break throughs >(possible, but not likely). Well, I have a couple of minor criticisms about the above statements. First of all, before every "breakthrough" in computer science, there is a long period of developing the background necessary to talk reasonably about the subject. For some people, this is most profitably spent reading articles about the subject. Indeed, I would agree that this is probably the most valuable part of "research". Yet another method of developing background is to talk to people who perhaps know more (there are lots accessible from news) or have done research in the area. I have benefitted tremendously by receiving the enthusiastic responses of several people in the field of computer graphics, many of whom I have never met face to face. Much of my "research" is actually spent in understanding ideas that have come before, and trying to push them in new ways, categorize them in ways that might make tenuous connections more clear, and coalesce fuzzy ideas into clear concepts. The net is a great medium for doing this, because it allows you to converse with lots of people who are doing the same. Second, the "amateur" quality of the postings may be clear to you, but they aren't clear to me. I have found them interesting and thought provoking, which questions about "point-in-polygon" or "color pallette optimization" have failed to do. Yesterday I spent in a thought experiment about the possibilities of trying to do sound tracing with several of my collegues (posting to follow soon) which I thought had some interesting (and probably pretty obvious) insights. It also is relatively clear that it will work, and would be cheap in terms of hardware to implement. Third, your posting is itself noise. You offered none of the "classic" references. You offered no criticisms of proposed computational models. You shared no personal insights. You tossed a bucket of water on people who are anxious to learn. Shame on you! >It would be nice to see just a few postings with references to the >classical references in the field. After these have been explored, the >net is a good place to make comments and to further discuss nuances not >covered in standard books or journals. I agree, but I think if we confine ourselves to doing that, beginners won't catch on to the excitement and interesting ideas that are all through computer science. Let's keep the excitement of discovery in computer science, and recognize individual discovery as a valid form of research and academic pursuit. I am finding this line of conversation profitable and exciting. I urge everyone to keep thinking, keep posting, keep criticizing, and keep researching. And look for my probably amateur posting about sound tracing.... Mark VandeWettering
kjartan@raunvis.UUCP (Kjartan Pierre Emilsson Jardedlisfraedi) (01/02/89)
In article <7488@watcgl.waterloo.edu> ksbooth@watcgl.waterloo.edu (Kelly Booth) writes: > (...) It is highly unlikely that a couple of hackers thinking abou >the problem for a few minutes will generate startling break throughs >(possible, but not likely). and in <3435@uoregon.uoregon.edu> markv@uoregon.uoregon.edu (Mark VandeWettering) replies: >> (...) >> Third, your posting is itself noise. You offered none of the >> "classic" references. You offered no criticisms of proposed >> computational models. You shared no personal insights. You >> tossed a bucket of water on people who are anxious to learn. >> Shame on you! and we thank you, Mark, for this support. It is an interesting behavioural aspect of the Net, that there always seems to be someone who is immensly annoyed by the fact that a lot of people are having pleasure talking about some subject, which they themselve find boring, uninteresting or not up to their standards. This annoyance eventually gets up to such a point that the person goes through a series of multiple duplications, suddenly becoming an authoritative "We" who thinks it is its duty to informate the babbling crowd about what it should do and how it should do it. Kelly: We are fully aware that sound tracing is a known topic one of us being an architect, another a physicist and the third a sound engineer (This sounds like the beginning of some joke). And as you said, there is a lot of money in this field, and that also mean that very little is publicated. The reason why we decided to check the Net for this subject is simply because we think that it is a perfect database: human driven. We also think that innocent discussion is quite enjoyable and often fruitful. -Kjartan & Dagur -------------------------------------------------------------------------- Kjartan Pierre Emilsson Science Institute - University of Iceland Dunhaga 3 107 Reykjavik Iceland Internet: kjartan@raunvis.hi.is
david@epicb.UUCP (David P. Cook) (01/03/89)
>In article <7488@watcgl.waterloo.edu> ksbooth@watcgl.waterloo.edu (Kelly Booth) writes: >>We are being flooded by a lot of amateur postings about ray tracing for >>sound. This is not a new idea and it is not a new topic. Most of the >>postings appear to be quite naive approaches. There are commercial >>companies that have applied computer techniques to problems in >>acoustics for many years. There are big bucks to be made in this >>field. It is highly unlikely that a couple of hackers thinking about >>the problem for a few minutes will generate startling break throughs >>(possible, but not likely). While Mark VandeWettering responded wonderfully in his *flame* back on this original posting, I thought I would add my 1 1/2 cents :-). The statement made above: "It is highly unlikely that a couple of hackers thinking about the problem for a few minutes will generate startling break throughs." Is appaling! Sound processing is CENTURIES behind image processing. If we were to apply even a few of our common algorithms to the audio spectrum, it would revolutionize the synthizer world. These people are living in the stone age (with the exception of a few such as Kuerdswell [sp]). What happens if you XOR a trumpet and a flute? What happens if you CONTRAST STRETCH an electronic organ? What happens if you PAINT into the sound spectrum? What happens if you FUZZ the frequencys, or ADSR? Antialiasing? Quantization (not note guys!)? RAY TRACKING??? Particle System Theory? Fractals (this has been done)? No, this is not a WELL RESEARCHED area as Kelly would have us believe. The sound people are generally not attacking sound synthesis as we attack vision synthesis. This is wonderful thinking, KEEP IT UP! -- | David P. Cook Net: uunet!epicb!david | | Truevision Inc. | "Sometimes I cover my mouth with | | Indianapolis, IN | my hand to tell if I'm breathing" | -----------------------------------------------------------
riley@batcomputer.tn.cornell.edu (Daniel S. Riley) (01/04/89)
In article <572@epicb.UUCP> david@epicb.UUCP (David P. Cook) writes: >>In article <7488@watcgl.waterloo.edu> ksbooth@watcgl.waterloo.edu (Kelly Booth) writes: >>>[...] It is highly unlikely that a couple of hackers thinking about >>>the problem for a few minutes will generate startling break throughs >>>(possible, but not likely). Ok, I think most of us can agree that this was a reprehensible attempt at arbitrary censorship of an interesting discussion. Even if some of the discussion is amateurish and naive. > The statement made above [...] > Is appaling! Sound processing is CENTURIES behind image processing. > If we were to apply even a few of our common algorithms > to the audio spectrum, it would revolutionize the > synthizer world. These people are living in the stone > age (with the exception of a few such as Kuerdswell [sp]). On the other hand, I think David is *seriously* underestimating the state of the art in sound processing and generation. Yes, Ray Kurzweil has done lots of interesting work, but so have many other people. Of the examples David gives, most (xor'ing, contrast stretching, fuzzing, antialiasing and quantization) are as elementary in sound processing as they are in image processing. Sure, your typical music store synthesizer/sampler doesn't offer these features (though some come close--especially the E-mu's), but neither does your vcr. And the work Kurzweil music and Kurzweil applied intelligence have done on instrument modelling and speech recognition go WAY beyond any of these elementary techniques. The one example I really don't know about is ray tracing. Sound tracing is certainly used in some aspects of reverb design, and perhaps other areas of acoustics, but I don't know at what level diffraction is handled--and diffraction is a big effect with sound propagation. You also have to worry about phases, interference, and lots of other fun effects that you can (to first order) ignore in ray tracing. References, anyone? (Perhaps I should resubscribe to comp.music, and try there...) (off on a tangent: does any one know of work on ray tracers that will do things like coherent light sources, interference, diffraction, etc? In particular, anyone have a ray tracer that will do laser speckling right? I'm pretty naive about the state of the art in image synthesis, so I have no idea if such beasts exist. It looks like a hard problem to me, but I'm just a physicist...) >No, this is not a WELL RESEARCHED area as Kelly would have us believe. The >sound people are generally not attacking sound synthesis as we attack >vision synthesis. This is wonderful thinking, KEEP IT UP! Much work in sound synthesis has been along lines similar to image synthesis. Some of it is proprietary, and the rest I think just receives less attention, since sound synthesis doesn't have quite the same level of perceived usefullness, or the "sexiness", of image synthesis. But it is there. Regardless, I agree with David that this is an interesting discussion, and I certainly don't mean to discourage any one from thinking or posting about it. -Dan Riley (dsr@lns61.tn.cornell.edu, cornell!batcomputer!riley) -Wilson Lab, Cornell U.
ksbooth@watcgl.waterloo.edu (Kelly Booth) (01/05/89)
What can I say. This is precisely what I was complaining about in my original posting (which was not, by the way, aimed at the the first posting on sound tracing, but at the follow up postings): >> Is appaling! Sound processing is CENTURIES behind image processing. >> If we were to apply even a few of our common algorithms >> to the audio spectrum, it would revolutionize the >> synthizer world. These people are living in the stone >> age (with the exception of a few such as Kuerdswell [sp]). The above quoted posting is what we see in comp.graphics all the time. If it isn't graphics, it must not be good and of course we can do better. My point (which I guess I stated pretty badly) was "Before you respond to a posting such as the sound tracing one with the first thing that comes out of your head in the way of a neat idea, why not take a little time to look through the available literature in the field if you are not familiar with it already. And once you have done this, why not include some references to it in your postings so the rest of us who might be interested are spared the trouble of searching out the references -- we can just go straight to the good sources you found."
paul@hpldola.HP.COM (Paul Bame) (01/06/89)
>(off on a tangent: does any one know of work on ray tracers that will >do things like coherent light sources, interference, diffraction, etc? >In particular, anyone have a ray tracer that will do laser speckling >right? A raytracer which did laser speckling right might also be able to display hologarms. -Paul Bame HP Colorado Springs hplabs!hpldola!paul paul@hpldola.hp.com
mary@dinorah.wustl.edu (Mary E. Leibach) (01/06/89)
ksbooth@watcgl.waterloo.edu (Kelly Booth) writes:
+We are being flooded by a lot of amateur postings about ray tracing for
+sound. This is not a new idea and it is not a new topic. Most of the
+postings appear to be quite naive approaches. There are commercial
+companies that have applied computer techniques to problems in
+acoustics for many years. There are big bucks to be made in this
+field. It is highly unlikely that a couple of hackers thinking about
+the problem for a few minutes will generate startling break throughs
+(possible, but not likely).
Gee, I started reading this group because I got VGA (I know, real primitive)
on my even more primitive PC/XT, and thought graphics was interesting and
wanted to learn more about it. I know I have only got a lowly B.S. degree,
and I haven't written any major papers, but I thought this was a group for
anyone to learn and trade techniques. And now you say you have to be a
professional (I AM a professional programmer) and make "big bucks". Well
since I am not in the big leagues, so to speak, perhaps I should go back
to rec.arts.comics for my graphic techniques! :-) After all, Wolverine has
some interesting methods of ray tracing people with his claws. :-) :-)
Talk about GRAPHIC violence! :-) :-) :-)
BTW, can someone recommend a good intro. book or two on graphics for an
AMATEUR who doesn't have the BIG BUCKS necessary to take a grad. course
in it right now. I'd really like to learn some more.
-Mary Leibach : Professional Programmer and Amateur Hacker
And PROUD of it!brent@itm.UUCP (Brent) (01/07/89)
Ok, here's some starting points: check out the work of
M. Schroeder at the Gottingen. (Barbarian keybord has no umlauts!)
Also see the recent design work on the Orange County Civic Auditorium
and the concert hall in New Zealand. These should get you going in
the right direction. Dr. Schroeder laid the theoretical work and
others ran with it. As far as sound ray tracing and computer
acoustics being centuries behind, I doubt it. Dr. S. has done things
like record music in stereo in concert halls, digitized it, set up
playback equipment in an anechoic chamber (bldg 15 at Murry Hill),
measured the path from the right speaker to the left ear, and from
the left speaker to the right ear, digitized the music and did FFTs
to take out the "crossover paths" he measured. Then the music played
back sounded just like it did in the concert hall. All this was done
over a decade ago.
Also on acoustic ray tracing: sound is much "nastier" to figure
than pencil-rays of light. One must also consider the phase of the
sound, and the specific acoustic impedence of the reflecting surfaces.
Thus each reflection introduces a phase shift as well as direction
and magnitude changes. I haven't seen too many optical ray-tracers
worrying about interference and phase shift due to reflecting surfaces.
Plus you have to enter vast world of phychoacoustics, or how the
ear hears sound. In designing auditoria one must consider "binaural
dissimilarity" (Orange County) and the much-debated "auditory backward
inhibition" (see the Lincoln Center re-designs). Resonance?? how many
optical chambers resonate? (outside lasers?) All in all, modern
acoustic simulations bear much more resemblance to Quantum Mechanic
"particle in the concert hall" type calculations than to simple
ray-traced optics.
Postscript: eye-to-source optical ray tracing is a restatement
of Rayleigh's "reciprocity principle of sound" of about a century ago.
Acoustitions have been using it for at least that long.
happy listening,
brent laminack (gatech!itm!brent)jevans@cpsc.ucalgary.ca (David Jevans) (01/09/89)
In article <11390016@hpldola.HP.COM>, paul@hpldola.HP.COM (Paul Bame) writes: > A raytracer which did laser speckling right might also be able > to display hologarms. A grad student at the U of Calgary a couple of years ago did something like this. He was using holographic techniques for character recognition, and could generate synthetic holograms. Also, what about Pixar? See IEEE CG&A 3 issues ago. David Jevans, U of Calgary Computer Science, Calgary AB T2N 1N4 Canada uucp: ...{ubc-cs,utai,alberta}!calgary!jevans