open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello

I want to interpolate some topographic values on a mesh but the result seems to be slightly different to what I expected.
I start with the mesh

I want to apply the values taken from this topographic file



as I work in a larger mesh, I use a constraint outline for the interpolator




The bottom left point value is 6.000 but when I map the interpolator2D on the mesh, the mesh node at the same location has the value 6.025!
I can't understand the reason behind this strange behaviour

Martin, could you help me or explain this behaviour if it's logical

Thanks in advance

I can reproduce this bug with a 2D Interpolator using the nearest neighbour method.
The bathymetry located at the border is not always taken into account. It seems that only bathymetric points strictly included in the footprint of the mesh are used in the interpolator.
I hope there is (or at least will be) a solution/correction to fix this.
Luc

Hi Christophe,

You uncovered a bug
This occurs under certain conditions when source data points in the interpolator are concident with nodes in the target mesh AND multiple source data points share the same X coordinates.
You can verify this by simply shifting either the mesh or the xyz points by a VERY small amount in X. (say 10e-6 in this case)

I will pass this on to Alan at NRC.
My apologies for any inconvenience this may have caused.

Cheers... Martin