
 Error in Render Scene number 24 


Posted: Thu Jul 25, 2013 12:01 am 



Hello,
I am trying to run a simulation with reverberation in an architectural ambitious train station. The acoustic model I did is quite simple (373 faces), but I have 60 speakers (3 different type). I would like to check the Direct SPL and STIPA with a background noise of 60.
I have an error in the simuation : Error in RenderScene in line 24.
Someone can advice how to bypass this error to get the result of the simulation?
Thanks and regards,
Guillaume Massardier 







Posted: Thu Jul 25, 2013 11:55 am 


AFMG Pedro Lima 
Forum Moderator 


Joined: 05 Jun 2010 
Posts: 233 
Location: Brazil 






Guillaume,
This error usually occurs whenever using too high resolution. In your case the number of speaker must be contributing also.
Have you tried restricting the number of speaker on per simulation? You can probably simulation sets of speakers depending on your model to examine áreas separetedly.
If I remember correctly, you tried to model the 60 dB noise floor by adding a number of speakers in order to create a line source. Is that right?
If that's the case, maybe it would be interesting considering this noise floor by means of the table with constant 1/3 octave noise values, instead of using the speakers. This should diminish considerably the calculation time.
If you want to, you can send me your model so that can take a closer look.
Hope this helps,
Pedro 







Posted: Fri Jul 26, 2013 12:57 am 



Hi Pedro,
Thanks for your prompt answer.
In fact, this one is another model. I just check the SPL distribution and the STI distribution on a plateforme with the existing equipment (So I cannot remove some speakers).
I am using a resolution of 0.5 with reverberation.
I send you an email with the model. Thanks and regards,
Guillaume 




Posted: Fri Jul 26, 2013 6:15 pm 


AFMG Pedro Lima 
Forum Moderator 


Joined: 05 Jun 2010 
Posts: 233 
Location: Brazil 






Guillaume,
What values for the RT are you using? Are you asking EASE to calculate them or you are using custom values?
Also, the STI calculations you are performing are based on Standard Mapping or AURA?
Pedro 







Posted: Fri Jul 26, 2013 6:37 pm 


AFMG Pedro Lima 
Forum Moderator 


Joined: 05 Jun 2010 
Posts: 233 
Location: Brazil 






Dear Guillaume,
I can see that there has been a considerable evolution with respect to the drawings since the last post you made. The ones you sent me seem already much better.
There still some issues to fix and observations to make, though:
Please check the Faces orientation. The yellow side is the reflective side (also the side that will use the Front Material). It seems there are a number of inverted Faces on you're drawing.
There are also some Two Fold Faces where there could be simple Faces. Some are also inverted.
There issues above are not important if you are performing Direct Sound calculation only. But:
If you would like to perform STI calculations you MUST have Faces being correctly used. Also, please notice that Eyring and Sabine formulae for the Reverberation Times do not apply for this train station model. Please refer to Eyring and Sabine for more information. That means you cannot estimate the STI by means of standard mapping (which uses information statistical for the RT based on that formulae). On should use raytracing based algorithms, such as the raytracing feature or AURA. In the later case you need to have a closed model (due to considerations for that algorithm). Although you have an open space, that should not be a problem. You can just close the model with 100% absorptive Faces where there are open spaces.
The errors you reported above are generated whenever you perform what type of calculation? Standard Mapping, AURA, Ray Tracing,...? What are the settings you use so that I can try to reproduce it?
Best Regards,
Pedro 







Posted: Tue Aug 01, 2017 4:32 pm 


hasia 
Member 


Joined: 26 Jan 2017 
Posts: 9 







Hi,
You mentioned that "Eyring and Sabine formulae for the Reverberation Times do not apply for this train station model. Please mention a reference. 







Posted: Wed Aug 02, 2017 9:39 am 


AFMG Pedro Lima 
Forum Moderator 


Joined: 05 Jun 2010 
Posts: 233 
Location: Brazil 






Dear Hasia,
Please let me provide you some overview of Mr. G. Massardier's model from 2013: it was the preliminary EASE model of a roughly 150 meters long by 30 meters wide train platform, with open sides, hard floor and relatively reflective  6 meters high  ceiling with a considerably large opening through it's extension, providing access for a second floor.
Quite a few equations to calculate the Reverberation Time of a room have been elaborated by different authors, since the introduction of the term by Sabine. These, in general, consider different assumptions for the room geometry and the distribution of the materials inside, so that the RT could be calculated for different room forms. If the requirements for a given formula are not met, the results may not be adequate. Being one of the oldest formulas, you will find numerous references to Sabine equation and more information on it's premises. Among these references:
 Lawrence E. Kinsler, Austin R. Frey, Alan B. Coppens, James V. Sanders, Fundamentals of Acoustics
 Michael Vorländer, Auralization: Fundamentals of Acoustics, Modelling, Simulation, Algorithms and Acoustic Virtual Reality
The platform above mentioned in general won't have a sound field that is diffuse enough. You can for instance already notice from the open sides in this rectangular space that sound will be largely "absorbed" in the horizontal direction, while it will persist for some time in the vertical direction. Roughly speaking.
I hope this helps clarifying the thoughts of my previous comment.
Best Regards,
Pedro 





 Limitation of the Sabine formula 


Posted: Mon Aug 28, 2017 6:30 pm 


hasia 
Member 


Joined: 26 Jan 2017 
Posts: 9 







Thanks Pedro for the explanation. 




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