Hey Fitz, what we need for this particular "experiment in pain" is a way to reset the ortho parameter from the normal 0 degrees to an angle that's the same as a selected line - in my old tired Dos Generic Cadd 6.1, I can type "OA", as in "Ortho Angle", then hit the = key, the program asks "like what", and I can just click on a line - when I do that, that line's angle becomes the NEW Ortho angle, with all new lines defaulting to that angle or one 90 degrees from it, making it very easy to draw perpendicular lines from the NEW reference surface without guesswork.
Somewhere there's a thread where I described how to do a poor man's Ray Trace to figure out RFZ angles, think it's in the Design forum - in that, I explained how I do it. What Aaron needs is a way to duplicate those changes in Autocad, if possible.
Go here -
http://www.johnlsayers.com/phpBB2/viewt ... c&start=60
and check my post of Jan 24 for an explanation of what we're trying to do... Steve
Walls-Walls & More Walls
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cadesignr
- Senior Member
- Posts: 566
- Joined: Mon Mar 03, 2003 4:25 pm
- Location: Oregon USA
Hi guys, well, that thread was very entertaining 
Especially your explaination, which btw, is WAY beyond me. I did post a response to Michaels thread at HR along the lines of this thread, that my initial thought to baffle extentions for rear surrounds, is that they are directly aimed back at your head, so early reflections had a perfect "mirror". As to ray tracing, I haven't a clue to what that is.
Although I've heard the term, and seen drawings of audio room analysis, using "ray tracing", it baffled me, as my interpretation of a sound wave is that it moves from a source as a hemispherical wavefront, and reflections are generated as new boundarys are encountered, also as hemispherical wavefronts, so the idea of a "ray" eludes me. But I've come to the point in my "quest" that I'm already so far behind current knowledge, that it makes no sense for me continue to "catch up", just to build my little studio.
As for changing the angle of the ortho function, never thought about it. I simply copy any line at any angle from any point to any point. Remember, I do simple CAD drawings, nothing in 3D, and although some of the stuff I've had to do was rather complex, I use very few commands to do it. My use of CAD doesn't require the more sophisticated capabilitys of the program. Although I constantly dabble with it, my daily work doesn't require it. I am pretty much self taught, and the depth of the program would take a lifetime to utilize, unless your doing rocket science, and have the time or money to take a course in it. I do not. Nor am I interested in exploiting the depth of it. Current time constraints, wish lists, "honey do's". and light at the end of the tunnel realizations, have forced me to adjust my use of time, to achieve reality instead of pipedreams.
There are other commands that I use all the time to achieve results that perhaps better informed users do with commands I'm not familiar with. One of them is the "mirror" command. You can mirror at any angle, and from any point to any point. Also the "align" command is very powerful. You can align an intity such as a line or groups, or blocks, to any other intity, at any angle you so desire. Explaining it here would be frustrating. A simple live demonstration took only seconds for me to see how it works, but I would suggest looking at the extensive help(F1) resource and typing in "align". I should explain it far easier than I can. BTW, if that plan drawing of a control room was an example of your understanding of CAD, then you have as much command of the program as I do, so I don't think this is very difficult to figure out how to do. Any line drawn at any angle can simply be copied from an endpoint to any point you want that line to start from. Then either extend it and trim it as required, or grab the end "grip" point and drag it to where you want it. Another way to extend a line, without changing its angle, is scale. A line is a vector, and scaling it will not change its plotting linestrength. It will however, change its length. Scale it from a midpoint(Osnaps)and it will extend both directions along its vector, to what ever length is desired. Then trim. I personally don't see a need for the angle of ortho being set for multiple parallel line creation, as you can draw multiple lines at 0 or 90 degrees and rotate them. And there are a multitude of other ways to draw lines at the same angle. But for one or two, or an array, or even multiple lines in parallel at even seperations, copying is the way to do it. However, there is an another simple command I use all the time. OFFSET. This command is simply a COPY command, whereby you automatic set the distance to which the intity is being copied TO, parallel with the original, even at an angle. Type in OFFSET, and it promps you for the distance to offset, which you type in whatever units you are using to dimension. One unit will equal what ever measuring system you have set in the dimension parameter settings. Either inches or Metric. Or even miles if your drawing that large. Ha! Autocad has 14 decimal places so you can draw in microns if need be. Same with offset.
Well, hope this helps. I am definetly no CAD teacher, but experience often illustrates a different way of looking at things.
Like my Dad. Hes a mechanic. A mechanic who never had any money. He learned to do things by necessity. Like crossing the desert in a Model T. When a main bearing fried, they simply lifted the car on its side, pulled the pan, removed the bearing cap, then made another temporary bearing from his leather belt. Beats death. He was 11 yrs old.
And when I needed a new alternator but could not afford one, and because the diodes were fried, he simply took the rear part of another type, with the diodes in it, and bolted it to the firewall, and ran wires to and from as required. Getting from point A to point B is all that matters when you have no other choice.
This doesn't mean that ortho can't be changed. I just never needed to.
fitZ
Especially your explaination, which btw, is WAY beyond me. I did post a response to Michaels thread at HR along the lines of this thread, that my initial thought to baffle extentions for rear surrounds, is that they are directly aimed back at your head, so early reflections had a perfect "mirror". As to ray tracing, I haven't a clue to what that is.Although I've heard the term, and seen drawings of audio room analysis, using "ray tracing", it baffled me, as my interpretation of a sound wave is that it moves from a source as a hemispherical wavefront, and reflections are generated as new boundarys are encountered, also as hemispherical wavefronts, so the idea of a "ray" eludes me. But I've come to the point in my "quest" that I'm already so far behind current knowledge, that it makes no sense for me continue to "catch up", just to build my little studio.
As for changing the angle of the ortho function, never thought about it. I simply copy any line at any angle from any point to any point. Remember, I do simple CAD drawings, nothing in 3D, and although some of the stuff I've had to do was rather complex, I use very few commands to do it. My use of CAD doesn't require the more sophisticated capabilitys of the program. Although I constantly dabble with it, my daily work doesn't require it. I am pretty much self taught, and the depth of the program would take a lifetime to utilize, unless your doing rocket science, and have the time or money to take a course in it. I do not. Nor am I interested in exploiting the depth of it. Current time constraints, wish lists, "honey do's". and light at the end of the tunnel realizations, have forced me to adjust my use of time, to achieve reality instead of pipedreams.
There are other commands that I use all the time to achieve results that perhaps better informed users do with commands I'm not familiar with. One of them is the "mirror" command. You can mirror at any angle, and from any point to any point. Also the "align" command is very powerful. You can align an intity such as a line or groups, or blocks, to any other intity, at any angle you so desire. Explaining it here would be frustrating. A simple live demonstration took only seconds for me to see how it works, but I would suggest looking at the extensive help(F1) resource and typing in "align". I should explain it far easier than I can. BTW, if that plan drawing of a control room was an example of your understanding of CAD, then you have as much command of the program as I do, so I don't think this is very difficult to figure out how to do. Any line drawn at any angle can simply be copied from an endpoint to any point you want that line to start from. Then either extend it and trim it as required, or grab the end "grip" point and drag it to where you want it. Another way to extend a line, without changing its angle, is scale. A line is a vector, and scaling it will not change its plotting linestrength. It will however, change its length. Scale it from a midpoint(Osnaps)and it will extend both directions along its vector, to what ever length is desired. Then trim. I personally don't see a need for the angle of ortho being set for multiple parallel line creation, as you can draw multiple lines at 0 or 90 degrees and rotate them. And there are a multitude of other ways to draw lines at the same angle. But for one or two, or an array, or even multiple lines in parallel at even seperations, copying is the way to do it. However, there is an another simple command I use all the time. OFFSET. This command is simply a COPY command, whereby you automatic set the distance to which the intity is being copied TO, parallel with the original, even at an angle. Type in OFFSET, and it promps you for the distance to offset, which you type in whatever units you are using to dimension. One unit will equal what ever measuring system you have set in the dimension parameter settings. Either inches or Metric. Or even miles if your drawing that large. Ha! Autocad has 14 decimal places so you can draw in microns if need be. Same with offset.
Well, hope this helps. I am definetly no CAD teacher, but experience often illustrates a different way of looking at things.
Like my Dad. Hes a mechanic. A mechanic who never had any money. He learned to do things by necessity. Like crossing the desert in a Model T. When a main bearing fried, they simply lifted the car on its side, pulled the pan, removed the bearing cap, then made another temporary bearing from his leather belt. Beats death. He was 11 yrs old.
And when I needed a new alternator but could not afford one, and because the diodes were fried, he simply took the rear part of another type, with the diodes in it, and bolted it to the firewall, and ran wires to and from as required. Getting from point A to point B is all that matters when you have no other choice.
This doesn't mean that ortho can't be changed. I just never needed to.
fitZ
alright, breaks over , back on your heads......
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knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
Cool, rick, sounds like we're in similar boats on the cad self-ed...
AS to ray tracing, you're right for lower frequencies - below about 300 hZ the wave thing seems to be the model, above that you can (sort of) consider sound to act as light (or a pool ball) and use simple geometry to figure out what will go in which direction -
Fortunately, reflections reduce in level fairly quickly with distance, so this laborious method doesn't have to be traced further than maybe the second thing that reflects - main thing is getting the level of the reflections several dB below that of the direct sound (forget how many dB, if I find it again I'll re-post)
Glad you brought up the Mirror command, that may be a simpler way that what I was doing for my "polish ray trace" scenario, thanks... Steve
AS to ray tracing, you're right for lower frequencies - below about 300 hZ the wave thing seems to be the model, above that you can (sort of) consider sound to act as light (or a pool ball) and use simple geometry to figure out what will go in which direction -
Fortunately, reflections reduce in level fairly quickly with distance, so this laborious method doesn't have to be traced further than maybe the second thing that reflects - main thing is getting the level of the reflections several dB below that of the direct sound (forget how many dB, if I find it again I'll re-post)
Glad you brought up the Mirror command, that may be a simpler way that what I was doing for my "polish ray trace" scenario, thanks... Steve
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AVare
- Confused, but not senile yet
- Posts: 2336
- Joined: Thu Feb 05, 2004 1:56 pm
- Location: Hanilton, Ontario, Canada
The spec in AES.EBU.the tonmeister SSF and ITU is that reflections in the first 15 milliseconds be at least 10 dB down.main thing is getting the level of the reflections several dB below that of the direct sound (forget how many dB, if I find it again I'll re-post)
Is that the one you are thinking of?