How is DEM taken into account in Noise Modelling ? about noisemodelling HOT 9 OPEN

Hi,

The results is using the same geometry as input, so LDEN_GEOM is still at the relative height above the ground.

You can use confRaysName in order to see how your buildings have been placed with your DEM and to see a part of the rays (up to 5000) between sources and receivers.

from noisemodelling.

Hello,

Thank you for your reply. Do you know if Noise Modelling can take into account the DEM directly ? For example, if I put the DEM table first, is it possible to import other tables (like buildings, ground, roads...) and calculate receivers that will be put directy on the DEM (or at DEM+4meters) ? Or if a projection to put ground or roads at the same height exists in Noise Modelling ?

I have another try file where I have put all my buildings, ground, and roads at the same height of the DEM. I created a regular_grid with Noise Modelling and reajust the grid at the DEM height by exporting the file and assign a new 'HEIGHT' on QGIS. I created then a triangle table by QGIS with the same formalism than Noise Modelling uses. You can find this file attached to my message. Then, I started the calculation after importing all the tables into Noise Modelling. I have all the results I want, except one : I can't have a contouring_noise_map table (it is empty) and I don't understand why. It seems to calculate but when I want to export it, there is an error :

Could you help me please ?
Limoges_1km2_essai_DEM_GITHUB.zip

By the previous message, I was hopping there was a faster method to take into account DEM into Noise Modelling.

Thanks for your reply,
Amandine

from noisemodelling.

Hello,

Do you know more about my question ? I just wanted to know how the DEM can be taken into account when calculating a noise map, and how do we do to succed in that.

Thank you in advance !
Amandine

from noisemodelling.

Hi,

I don't understand your issue. Dem is taken into account, you just have to provide a dem table.

You can follow this tutorial to understand how to provide it:

https://noisemodelling.readthedocs.io/en/latest/Get_Started_GUI.html

best regards,

from noisemodelling.

Hi,

The fact is that when I import my tables BUILDINGS, GROUND, and ROADS into Noise Modelling, the height assigned is 0 (the sea level) for each table. And even if I put a DEM table by importing an ASC file, the final result is still at an altitude of zero into QGIS.
Then I was wondering how DEM can be taken into account when Noise Modelling is calculating the receivers table, because in order to run the calculation, there is no question of DEM table into the input parameters of the grid's blocks.

So my question is : how can the input tables (roads, buildings, ground) are projected on the DEM on Noise Modelling ? Because in my case, it doesn't seems to work, even if I import a DEM table into the WPS builder.

Can you explain me ?

Thank you for your time,
Best Regards

from noisemodelling.

The dem is not reported to LDEN_GEOM result file. But the propagation use the parameter DEM table name.

In all input tables you have to specify the height, not the altitude.

https://noisemodelling.readthedocs.io/en/latest/Input_roads.html
https://noisemodelling.readthedocs.io/en/latest/Input_buildings.html

best regards,

from noisemodelling.

Hello,

Thank you for your reply.
I have tried some small cases to see how the taking into account DEM is working.
I have a question about it. I tried 3 cases :
-1st case : not many road traffic, and DEM taken into account
-2nd case : more traffic than in the 1st case, also with DEM taken into account
-3rd case : the same traffic as the 2nd case, but with no DEM (Z=20m everywhere)

The results from the 3rd case seems logical with LDEN_GEOM, but the CONTOURING_NOISE_MAP doesn't seem to return the same results as we have on the LDEN_GEOM shape.

The results from the 1st and 2nd case seem weird because there is more than the half of the points from LDEN_GEOM that are assigned "-92,01" to LAEQ (represented in black in the following pictures). Is it normal ?

I give you my file work also :
Essai_3.zip

Waiting for your reply,
Best regards

from noisemodelling.

Hi,

The dem should cover the source geometries + the propagation distance you have set.

It is not the case here

from noisemodelling.

Hi,

I have enlargered my DEM zone and now it works. Thank you !

Best regards

from noisemodelling.