Sound modeling from AutoCAD 3D?

[RevMen]

Originally Posted by VolvoHeretic

I've tried the free sketch-up, it sucks! With no dimensions, how do you know what you are drawing?

That's an odd thing to say. Why do you think there are no dimensions?

Sketchup is better than you guys are giving it credit for. It's absolutely not a replacement for AutoCAD or Revit and it doesn't pretend to be. You have to think in 3 dimensions, and you have to think about the level of detail that's useful for modeling a listening space. I'm not talking about modeling in the sense that it performs an acoustical analysis, only in the sense that it allows you to convey the physical realities of your listening space to others perfectly.

But that doesn't mean that it will never be able to do acoustics analysis. Do a search for ray-tracing plugins and you might find yourself surprised at its spacial modeling capabilities. I've not found an acoustic ray-trace plugin, but that just means no one has written one yet. The ability to assign material properties to surfaces is built in and it uses Ruby to run scripts, which is the most user-friendly language known to man. Writing an acoustic ray-trace plugin will be far, far easier than writing a LISP routine to accomplish the same thing in AutoCAD.

Actually, now that I think about it, there is a new sketchup-based product on the market for outdoor noise analysis called Olive Tree Lab. The author posted the beta version in an acoustics group on Linked-In and I tried it out a few months ago. It seemed promising. It was a little rough, but I think he's made some refinements since then (and started charging for it). That software isn't useful for audiophiles, since our problems are single room, indoor, but it illustrates very nicely that Sketchup can be an excellent platform for acoustical analysis.

I am dreaming of a concave curved speaker/end wall

Unless your goal is to concentrate sound to a specific point in space, stay very far away from concave curved surfaces. Curved mirrors work just as well for sound as they do for EMR.

I guess it would be cool for a mono system, but this would absolutely wreck a stereo image. It'd sure be loud, though!

Here's me in Seattle in front of the children's museum. They have a set of "whisper dishes" set up, which are a blast to play with. There's a little iron ring on each dish which shows you where the focal point is. One person stands at each dish with their heads near the rings and you can hear each other whispering clearly across the courtyard.

[tomlinmgt]

Originally Posted by VolvoHeretic

Back in the '70's those TA's were as good as it got. Unfortunately, as tire technology advanced, they never supported the 15" wheel size. And it's got an air dam, able to punt small animals and children harmlessly out of the way.
A vitual sound room should be easily able to see a 3d room, but maybe it still needs the power of a super computer to do the math like a CFD vitual wind tunnel program.

And a big chrome bumper to blind 'em right before they get relocated!
No doubt, canyon carving' in the 70's on street tires was very, um...harcore. I gotta know, were you pumpin any tunes during those twisty two-lane assaults and if so, what/who put in the zone? Sorry I'm off topic guys, but this is pretty radical stuff for a car guy. I gotta' ask.

[VolvoHeretic]

Ok, no concave walls. I was just thinking of how great the little fiberglass round dome house a friend rented and how the accustics in there sounded with a little stereo back in the '70's. I guess I can't remember how Sketch worked except that I couldn't do anything with it, and wondered how people were drawing such unbelievably good car drawings with it

That car is so loud that you couldn't hear the 7 watt cassette deck anyways, but it was Led Zepplin and Pink Floyd.

[tomlinmgt]

A casette deck in your car in the 70's. You must've gotten all the chicks with that thing! Too cool, man....too cool.

[tchuck]

Originally Posted by RevMen

...
Sketchup is better than you guys are giving it credit for. It's absolutely not a replacement for AutoCAD or Revit and it doesn't pretend to be. You have to think in 3 dimensions, and you have to think about the level of detail that's useful for modeling a listening space. I'm not talking about modeling in the sense that it performs an acoustical analysis, only in the sense that it allows you to convey the physical realities of your listening space to others perfectly.

...

I may be slightly underselling Sketchup, but on the same token I think you're downplaying the realities of engineering analysis.

Think in three dimensions? AutoCAD and Revit are both extremely capable 3D modeling applications. I think it's safe to say we're all thinking in three dimensions here. You keep referring to "modeling" a listening room, but if you read the first post of this thread you will realize that what the OP is actually looking for is analysis, not modeling. In post #5 you can see that he has already modeled his room in AutoCAD. How can Sketchup possibly improve upon what he has already done? Sketchup's forte is rendering, and even in that tiny area ACAD is far superior.

Originally Posted by RevMen

...
But that doesn't mean that it will never be able to do acoustics analysis. Do a search for ray-tracing plugins and you might find yourself surprised at its spacial modeling capabilities. I've not found an acoustic ray-trace plugin, but that just means no one has written one yet. The ability to assign material properties to surfaces is built in and it uses Ruby to run scripts, which is the most user-friendly language known to man. Writing an acoustic ray-trace plugin will be far, far easier than writing a LISP routine to accomplish the same thing in AutoCAD.
...

"Never" is a powerful term. I'm not saying Sketchup will never be able to do acoustic analysis, I'm saying it can't do it right now. The OP isn't trying to analyze some hypothetical room at some infinite point in the future. He's trying to do it with an existing design right now.
Analysis with a LISP routine? I've written a lot of LISP routines for myriad situations and the idea of performing acoustic analysis with one is ridiculous to me. I'm not saying it's impossible, but way, WAY outside anything I've ever seen done with LISP.

Originally Posted by RevMen

...
Actually, now that I think about it, there is a new sketchup-based product on the market for outdoor noise analysis called Olive Tree Lab. The author posted the beta version in an acoustics group on Linked-In and I tried it out a few months ago. It seemed promising. It was a little rough, but I think he's made some refinements since then (and started charging for it). That software isn't useful for audiophiles, since our problems are single room, indoor, but it illustrates very nicely that Sketchup can be an excellent platform for acoustical analysis.
...

That Olive Tree Labs software is a stand alone acoustic analysis application, not Sketchup. Saying it's a "sketchup based product" is like saying an F1 engine is a "Model-T based product". On the most basic level perhaps, but not even close really. If you look at this LINK you will see exactly what separates the two programs in terms of acoustic capabilities. In Terrain you specify the actual physical properties of materials. In Sketchup you specify only the visual properties.

[RevMen]

Originally Posted by tchuck

I may be slightly underselling Sketchup, but on the same token I think you're downplaying the realities of engineering analysis.

I understand where you're coming from, but I think you're overemphasizing the similarity between outright building design and tuning of a room. The tolerances for this process are on the order of several inches. Also, I think we have different understandings of the problem statement.

This is the original request:

If so, can you highly trained sound engineers calculate where I should sit to avoid all of the nodes and voids and where to place my speakers and how to set my EQ?

While you may have taken that to mean "can someone plug my AutoCAD model into acoustic modeling software," I took it to mean "can someone use the information in this model to do calculation that will help my room."

This is why I suggested modeling his room in Sketchup, because a Sketchup model would transmit the same information to us in a format that would be useful to any of us, not just those of us with AutoCAD. I'm not suggesting that he re-model his room, btw. In his first post he said that he could model it in AutoCAD, not that he had.

The motivation for touting the use of Sketchup for us in this forum to communicate our rooms to one another comes from experience. I do acoustical engineering analysis on a daily basis and I've found Sketchup to be more useful than AutoCAD for many tasks. Of course we have AutoCAD at our firm, but I actually don't use it very often (only to read client drawings).

When we make recommendations for acoustical treatment or mitigation, the important parts of what we're telling a client, what to do and why to do it, can easily get lost in an AutoCAD drawing. In Sketchup I can de-emphasize absolute dimensions and emphasize the principals at work. I don't actually send Sketchup models to clients, but I sometimes take snapshots from inside a model to insert as figures into a report, and they usually do a great job of getting the point across.

I'm really not the first to think of this use for Sketchup, not by a long shot. If you want an example of how Sketchup can be useful for a forum like ours, spend a little time checking out the models people have built at the John Sayers forum. They've been using it for years there to help one another do great acoustics.

[tchuck]

Originally Posted by RevMen

...Also, I think we have different understandings of the problem statement.

...

I agree that this is the root of our disagreement.

I also agree that Sketchup can be used to aid in visualization, but I see that as being an extremely primitive form of acoustical analysis.

So, if the OP walked into your firm, how would you use Sketchup to dissuade him from the curved back wall idea? Or better yet, how could HE use Sketchup to determine the viability (or lack thereof) of his curved wall idea? He already knows how to use AutoCAD, so the learning curve point is moot.


Sent from my BlackBerry 9800 using Tapatalk

[RevMen]

Originally Posted by tchuck

So, if the OP walked into your firm, how would you use Sketchup to dissuade him from the curved back wall idea?

Again, I'm talking about using Sketchup (and AutoCAD) for visualization and transmittal of dimensions. Not for analysis.

But to answer your question, I would use Sketchup, AutoCAD, or a sheet of paper in the same way to dissuade him from using a curved back wall. It's not a very complicated concept, so it really doesn't require software to communicate it. I would draw lines showing how an inwardly curved back wall would focus reflections to the center of the room, thereby allowing both speakers to "exist" on both sides of the room simultaneously, wrecking the stereo image.

Or better yet, how could HE use Sketchup to determine the viability (or lack thereof) of his curved wall idea? He already knows how to use AutoCAD, so the learning curve point is moot.

If he's interested in working on the problem by himself, then he should use whatever tool is most comfortable for him. Just like with mirrors, the angle of incidence is the same as the angle of reflection. Solving this problem in particular doesn't require any acoustical analysis software, just the ability to draw rays at specific angles.

but I see that as being an extremely primitive form of acoustical analysis.

You keep referring to some kind of acoustical analysis tool. What is it that you're talking about?

The most important room acoustics programs I know of are CATT, ODEON, and EASE. Is it one of these? There are some other packages out there that aren't as popular, as well. I haven't used CATT, but I have used both EASE and ODEON.

All 3 of them can work with Sketchup models, by the way. And a lot of people prefer Sketchup to any other interface for modeling a room. Like I said before, Skeptchup's level of detail is very consistent with the level of detail needed to do acoustical analysis.

ODEON:

We have made a plug-in for Google SketchUp (SU) that allow you to make direct use of SU models in ODEON. SU is a fun 3D modeling software which is operated very intuitively.

CATT:

SU²CATT is a SketchUp extension to export SketchUp models to CATT-Acoustic files. It exports models generated within Sketchup to the native .geo-format of CATT-Acoustic, including export of layers into several .geo-files and separate file with absorption material definition (ABS-directive in CATT).

If you've made your acoustic models within CATT before, this will save you tons of time. We actually developed the interface for in-house use first, and later decided that other people might benefit from it too.

"The use of SketchUp allows the user to create a building model for simulation VERY quickly and intuitively. It allows the software people to focus on the thing they are good at (Energy / Daylight / Acoustic modelling ) rather than on visualisation and geometrical modelling. It brings closer my personal Nirvana: Skecth design using full simulation tools, rather than cut-down 'simplifications'. What is most important to me, after many years of working with various geometry exporters based on the autodesk 3ds or dxf formats, is that in the experiments I have done with Daysim and CATT, the models exported from SketchUp are much less complex. Fewer polygons. Less calculation time. Less need for this type of geometry simplification."

EASE:

SU²EASE is a plugin for the 3D Software Google Sketchup to export Acoustic 3D-Models for use in EASE or Bose Modeler...
Main Features include:
-exports to .xfc format for use in EASE or Modeler
-Materials can be assigned within Sketchup
-Supports EASE standard material libraries
-integrated error recognition for common modelling errors

EASE:

EASE has the ability to import and export AutoCad and Sketchup DXF files

In finding those sources, I came across some other software packages I didn't know about or had heard of but never looked at.

Axys DDA:

Models can be imported into DDA from Odeon® , CATT Acoustic® and EASE® acoustic modelling software packages. Third party plug-ins are also available to import Google SketchUp® drawings into DDA.

L-Acoustics Soundvision:

SU4AC is a Google SketchUp plug-in written by Greg Longtin of Champion Enterprises. It is designed to help one quickly work with DXF, DWG and 3DS models imported from CAD software or acoustic simulation packages such as CATT, EASE and ODEON where one needs to reduce the model to what is required for electro-acoustic prediction. The sound designer can export and import models to/from SOUNDVISION.

Also note that this example is a Sketchup plugin that can act as a wheel-house between different acoustical packages.


And hey, look what I found: http://forums.sketchucation.com/view...df6b4ba80cf1bc. Sketchup plugin for acoustic ray-trace. I don't know how well it works but maybe it's useful for us.

[tchuck]

Ok, I don't want to beat a dead horse here, as it's obvious we are talking about two different things, but what I see above is this: You've listed a bunch of programs that WILL perform the task at hand (acoustic analysis), and illustrated the fact that they are all compatible with Sketchup in some capacity. You've proposed the idea that someone trained in acoustics could use Sketchup alone to perform basic raytracing, but that the same person could also use a pencil and a sheet of paper to the same end... Which pretty much echos what I've been trying to say in the last several posts: Sketchup is not the right tool for performing any kind of acoustical analysis, even if the analysis required is so basic as to solely require simple raytracing. (Because even then, someone like yourself would have to provide the knowledge to do the raytracing properly and to then draw intelligent conclusions from the resulting data.)

I still don't see how it will help a guy trying to figure out the effects of a curved back wall on overall sound or where to place his chair to avoid standing waves...

Maybe the OP can chime in here to clarify the original question. Specifically, what he meant by "sound modeling".

[RevMen]

Originally Posted by tchuck

I still don't see how it will help a guy trying to figure out the effects of a curved back wall on overall sound or where to place his chair to avoid standing waves...

His original question was about room modes. Room modes are pretty easy to solve because they're just based on the room's dimensions. To answer the question he's asking, we really only need to know the distances between opposing corners and flat surfaces.

Both AutoCAD and Sketchup models of his room would be helpful, because both would enable us to quickly extract distances between meaningful locations with a few clicks of the mouse.

This is why I suggested he consider creating a Sketchup model instead, as it would be a quick and convenient way for him to transmit all of the room's dimensions in one model that anyone here could download and observe, not just those of us with access to AutoCAD.

His second question, later in the thread, was about having a concave surface. It's a great question to ask on a forum like this, because I'm sure there are at least half a dozen people here who would instantly know not to do that. Problem solved.

It does not require any software to determine that a concave curved surface in a critical listening room is a bad idea. We don't even need room dimensions. Running a ray-trace on a room with a curved wall would reveal to us the location of the focal point, which I guess could be interesting, but it's not useful information in terms of answering the question. Knowing that there will be a focal point is all that's important.

Sketchup is not the right tool for performing any kind of acoustical analysis

No one is saying he should use Sketchup to perform an acoustical analysis, or that anyone here should use Sketchup to perform an acoustical analysis. I talked about the possibility of good scripts that allow us to do some ray traces in Skeptchup, but not once did I say Mr. Heretic should perform an acoustical analysis with Sketchup software (or software of any kind).

What I have been saying, over and over and over, is that Sketchup is a great tool for creating a model that can be transmitted to anyone. Such a model can inform someone of room dimensions for doing a hand calculation, or it can be imported into all of the major room acoustics software packages.

And that is the is the original intent of this thread.

Originally Posted by VolvoHeretic

I can 3D model my entire house in AutoCAD down to the nearest 1/8". If so, can you highly trained sound engineers calculate where I should sit to avoid all of the nodes and voids and where to place my speakers and how to set my EQ?

The OP was not talking about doing the analysis himself. He was talking about whether a model of his room that he built in AutoCAD could be used by someone to analyze his room. The answer to that question is yes.

It is also true that a Sketchup model could be used for the exact same task and, in fact, would be more useful, because it could be transmitted to anyone on the forum who was interested in taking a look.

Originally Posted by tchuck

You're on the right track, but you'll need to find someone with some sound analysis software, preferably someone who really knows how to use it, and find out what they need from you in terms of a file format. If there's a way for them to import a model, chances are good that AutoCAD can export the right format.

Your interpretation of his question was whether an AutoCAD drawing would be suitable for importing into an acoustical analysis package. You suggested he find out what file format to use. One of the best answers to that question is "Sketchup." Another good answer is "a .dxf export from AutoCAD."

[VolvoHeretic]

Thanks guys. When I first posted, I didn't have a model, but it only took 15 minutes to create and twice that long to upload to the server and post. I was hoping you guys used software that could show all of the sound anomalies similar to that Olive Tree Terrain, but it's just like CFD analysis, everything you find on the internet is stuff for sale, but no one to providing the services, but I haven’t actually looked either.

I will just continue to try and visualize sound without a clue, my best luck so far is to thing of the 2D waves splashing around in a crowded pool and how the waves in the corners build up and splash out.

How about convex walls then?

[tchuck]

Ugh. How about this: We stop bickering over this stupid software issue and you answer the guy's intensely simple question that apparently only requires room dimensions and a calculator. Ok?

[tchuck]

Originally Posted by VolvoHeretic

... was hoping you guys used software that could show all of the sound anomalies similar to that Olive Tree Terrain, ...

Sorry man, I'm going to stop clogging your thread with BS and maybe someone will hook you up with a quick and dirty analysis.

[RevMen]

Originally Posted by VolvoHeretic

How about convex walls then?

Much better than concave, but really not necessary. It would take up space that you don't have to sacrifice.

So can you give us the basic dimensions of your room and the existing surfaces? I can see from the picture you've posted that it's long and skinny but that's about all I can tell.

[VolvoHeretic]

It's not that long. I just measured it and will post it up when I get a chance. I will also recheck Sketchup and see if it doesn't suck so much this time.