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Hi,

I'm using Blue Kenue to map the impact of a restoration project on floods, here is how I’m proceeding:
- I'm mapping my mesh with a 2D interpolator with current bathymetry (.xyz) and modelling on telemac
- Then I remove points from my bathymetry and add 3D lines in the wholes to map my project and model it on telemac
- I have two identic meshes with current and project variables (bathymetry, height, velocity…) and I’m comparing those two meshes with blue kenue Calculator.
Usually it works fine and my bathymetry changes only where I removed points, but this time I have slight changes in my whole domain...
I checked my interpolators and they both use the same method (inverse distance), my bathymetry files are exactly the same except from where I removed points (which is very limited in comparison with my domain extent). I tried to remap various time my mesh but both keep being slightly different.
Also, my bathymetry covers only 95% of my domain (I used 3D lines on the rest) and I noticed that the changes occurred only in the bathymetry file extent.
Does anyone have a clue of where this could be coming from? Could it be “normal” that blue kenue maps differently with the same method and data?
Some more information:
- The density of my bathymetry file is 1 point/sq m
- The size of my elements varies between 1 and 5 meters
- I’ve already mapped the impact this way successfully with similar meshes and bathymetry
Thanks and let me know if you need more information.

Rafael

Hi
Some illustrations will probably help us to well understand the problem

Regards

Hi,

You can find attached :
- one view of the difference between my project vs current mesh bottom. The red lines are where I modified the bathymetry and the yellow line my domain extent
- another view of the extent of the xyz bathymetry (LIDAR) I used to map the meshes.

I usually run my simulations at different coordinates than I'm mapping them (I'm shifting my mesh coordinates to 3000, 6000 rather than 663000, 6246000).
Thanks in advance.

Rafael

Hi

It's clearer but some questions remains (for me).
If I understand well, you create your mesh once.
Then you map your bathymetry to build the current state.
You cancel the date in your project area, put some 3D lines in the hole created and map the new bathymetry to build the project state.

When you map the project state, did you map the bathymetry on the whole mesh? (I suppose it was on the whole mesh...)
In the 2D interpolator, did you use the Max Search Distance? (I suppose no)

So I think the problems comes from this last point. As you lidar density is important, you could (should?) limit the search distance otherwise small modifications far away could have a small impact on a large area.
You could also try to map the project bathymetry only locally with a constraint outline in a 2D interpolator specially dedicated to the project.

Hope this helps

Hi again,

Yes, you understand well.
To answer your last questions :
- Yes I'm mapping the whole mes for both scenarios
- I didn't use the max search distance because outside of my lidar (on the left of my mesh in the previous view), I have only a few 3D lines apart from more than 50 meters.
I suppose the best solution would be to map with a constraint outline only where my project is impacting my bathymetry, which actually makes much more sense.

Thanks for your help,

Regards