Absorption coefficient G

[fil123]

Hi,

• G : the acoustic absorption of a ground (FLOAT between 0 : very hard and 1 : very soft), according to END scheme, infact "he END scheme [55], is similar to IS09613-2 [1] in that it allows for frequency-dependent ground effect over non-flat ground by defining equivalent heights (see Section 12.10) and using a dimensionless frequency-independent coefficient, ground factor, G, with values between 0 (acoustically hard) and 1 (acoustically soft) according to the type of ground [55]". I noticed importing OSM maps that G related to water basins have an assigned G equal to 1. (https://www.openstreetmap.org/export#map=18/39.22652/9.20618).

The color Blue is water, based on your classification G could be 0. I hope that in calculation you use (1-G).
Can you clarify this point please?
I hope hearing from you soon.
Best regards.
Filippo Locci

[nicolas-f]

Hi,

In the last release of NoiseModelling water surface are exported with G value of 0.3

https://github.com/Universite-Gustave-Eiffel/NoiseModelling/blob/4.X/wps_scripts/src/main/groovy/org/noise_planet/noisemodelling/wps/Import_and_Export/Import_OSM.groovy#L928

@Nitnelav, why is it 0.3 instead of 0 ?

[Nitnelav]

Good question, I used the values from Geoclimate without questionning anything, it might be a mistake

[nicolas-f]

Ok, maybe it was arbitrary values on Geoclimate, we should use the values from Cnossos:

https://noisemodelling.readthedocs.io/en/latest/Input_ground.html#id1

[pierromond]

It should be 0 then... :)