NoiseM@p was not compared with other programs and thankfully ... as they do not all give the same results (integrating NMPB sometimes leads to differences in interpretation or in arbitrary choices)!
In fact, NoiseM@p has been validated on the basis of the reference configurations presented in the NMPB Sétra document (cf. internship of Adrien Lebellec). This is ongoing.
Directeur de Recherche (HDR)
Directeur du Laboratoire d'Acoustique Environnementale (LAE)
Activités du Laboratoire d'Acoustique Environnementale : www.lae.ifsttar.fr
Un logiciel open-source pour l'acoustique des salles : I-Simpa (i-simpa.ifsttar.fr)
Un logiciel open-source pour des études d'impact en milieu extérieur : NoiseM@p (noisemap.orbisgis.org)
Une base de données expérimentale pour l'étude de la propagation acoustique en milieu extérieur : LTMS 2002-2007 (http://ltms2002-2007.ifsttar.fr/)
I can add for the propagation module that basic laws of sound propagation and intersection test are also checked at each compilation of the project.
My intention was not at all to attack the software (sorry if you take it that way)... I was just wandering how you can validate such model.
I understand now that it was validated with a reference situation and not by comparing with other software (and it is perfectly logical).
When you validated NoiseM@p, what were the input parameters for the BR_TriGrid3D ? (**maximumPropagationDistance**, **maximumWallSeekingDistance**, **roadsWidth**, **receiversDensification**, **maximumAreaOfTriangle**, **soundReflectionOrder**, **soundDiffractionOrder**, **wallAlpha**).
I just want to be sure of the result I will have since there is no way of testing or comparing them. If I used a set of parameters that have been validated on a reference situation, I will be fine. I think the lower sets of validated parameters will better suit my problem because it will shorten my calculation time.
I assume this kind of tests have been done... If it is not the case, it is my problem and I will do my own test with these reference situations.
No problems at all, it is a meaningful question. BR_Trigrid is not used directly in scenarios, as it make a grid of receivers.
The limitation of source seeking distance are not covered by the NMPB specifications. You can find reference paper on this subject such as "PROBST, Wolfgang. Methods for the Calculation of Sound Propagation. DAGA 2008, 2008." that shows the importance of maximum ray length (maximumPropagationDistance parameter) in the computation of population noise exposure.