General questions on BR_TriGrid3D

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General questions on BR_TriGrid3D

Rodolphe
Does BR_TriGrid3D calculate the sound propagation with the sources in the specified area or does it take into account all the sources at less than ‘maximumPropagationDistance’ from the edges of the specified area ?

I don’t understand what the parameter ‘receiversDensification’ is.

I don’t understand the outputs of this function, what are representing W_V1, W_V2, W_V3 ?
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Re: General questions on BR_TriGrid3D

Nicolas F.
Administrator

Hi Rodolphe,

From each receiver point, BR_TRIGRID3D fetch sources up to the value of the parameter ‘maximumPropagationDistance’ (distance between receiver point and source point)

‘receiversDensification’ add receiver point perpendicular to noise source at specified distance.

W_V1, W_V2, W_V3 columns are sound pressure level in:

formula.png

In order to convert into dB(A) you have to call 10*LOG10(W_V1)

Regards,

-- 
Nicolas Fortin IRSTV FR CNRS 2488 GIS http://orbisgis.org Spatial DB http://h2gis.org Noise http://noisemap.orbisgis.org

Le 2015-02-19 13:13, Rodolphe [via OrbisGIS] a écrit :

Does BR_TriGrid3D calculate the sound propagation with the sources in the specified area or does it take into account all the sources at less than ‘maximumPropagationDistance’ from the edges of the specified area ?

I don’t understand what the parameter ‘receiversDensification’ is.

I don’t understand the outputs of this function, what are representing W_V1, W_V2, W_V3 ?

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Re: General questions on BR_TriGrid3D

Rodolphe
Hi Nicolas

First of all sorry for my first disrepectfull post (without any hello :/. I made a lot of following posts and forgot basic politeness). Thanks for your answer. It makes sense, I should have guess for the sound pressure.

But why three columns ? It means we have three different sound pressure in some triangles ?

Regards,
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Re: General questions on BR_TriGrid3D

Nicolas F.
Administrator
Hi Rodolphe,

In NMPB the receiver is evaluated in a point. Each point represent each vertex of the triangle. You can retrieve the coordinate by using ST_POINTN(ST_ExteriorRing(THE_GEOM), 1)

http://www.h2gis.org/docs/dev/ST_PointN/
http://www.h2gis.org/docs/dev/ST_ExteriorRing/

However, if you want to evaluate the sound level at a given coordinate you should use the BR_PTGRID function.

Regards,

Nicolas

Rodolphe wrote
Hi Nicolas

First of all sorry for my first disrepectfull post (without any hello :/. I made a lot of following posts and forgot basic politeness). Thanks for your answer. It makes sense, I should have guess for the sound pressure.

But why three columns ? It means we have three different sound pressure in some triangles ?

Regards,
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