Noise Map in LDEN

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Noise Map in LDEN

Rodolphe
This post was updated on .
Hi,

I assume it is possible to obtain a map in LDEN. However I have no idea of how to do it. I have separate data for day, evening and night. The combination of the three maps takes probably place after calculating the noise propagation with ST_BRTriGrid3D, but how do you do it? Is there a function for that?

Thanks.
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Re: Noise Map in LDEN

siberrian
I would like to know the same thing. I have separate maps, but how do you connect the data to obtain the final Lden map?
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Re: Noise Map in LDEN

Nicolas F.
Administrator
In reply to this post by Rodolphe
Hi,

LDEN is an average value on 24h and LN is an average value on 22h 6h

You have to apply a ratio on each sound source pressure level before doing propagation. There is an example here:

https://github.com/irstv/noisemap/blob/master/scripts/cete_traffic_to_noise/CompleteNoiseMapProcess.java#L218

Regards,

Nicolas Fortin
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Re: Noise Map in LDEN

Rodolphe
Hi,

Thanks, but there is something I don't understand. I am currently using OrbisGis version 5.0.0 and I have only access to an SQL Console. The script does not seem to be directly in SQL.

On the V3.0 documentation, I have read there is a Beanshell’s console but never find it. So I assume it is the code for the Beanshell’s console but how can I make this console appear ?

Thanks.
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Re: Noise Map in LDEN

Nicolas F.
Administrator

Hi,

This is a Groovy code. It just call SQL commands. You don’t have to use this groovy code as it is not adapted to your data.

The important SQL code is this:

create table LE_HCN as SELECT the_geom,10*(Log10((2/4)*Power(10,db_m/10))) as db_m FROM hcn_roads_dbm_global where db_m>0;
create table LE_HCJ as SELECT the_geom,10*(Log10((1/4)*Power(10,db_m/10))) as db_m FROM hcj_roads_dbm_global where db_m>0;
create table LE_HPS as SELECT the_geom,10*(Log10((1/4)*Power(10,db_m/10))) as db_m FROM hps_roads_dbm_global where db_m>0;

First is Night, second is day third is evening.

You can after merge the levels using energetic sum or by concatenate the tables using UNION ALL query.

2/4, 1/4 and 1/4 must fit with the time range of emission levels.

Regards,

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

Le 2015-02-25 14:05, Rodolphe [via OrbisGIS] a écrit :

Hi,

Thanks, but there is something I don't understand. I am currently using OrbisGis version 5.0.0 and I have only access to an SQL Console. The script does not seem to be directly in SQL.

On the V3.0 documentation, I have read there is a Beanshell’s console but never find it. So I assume it is the code for the Beanshell’s console but how can I make this console appear ?

Thanks.