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Hello all:
In the process of using bluekenue, I found that there were values in the mesh points which don't exist in the ".xyz" file. After observation, I found that Bluekenue has interpolated the value in the ".xyz" file. But that's not what I expected.
I want to know whether it is possible to turn off the interpolation function. Or,what should I do to meet my needs?
I would appreciate your reply.
Thank all
Song

Hi,

I have not personally experienced this issue but there are two ways you can perform the interpolation of scattered data onto the mesh. The first is by creating a T3S triangulation and mapping it to the grid. This will simply perform a linear interpolation.

The second is by using the 2D Interpolation which gives you more options regarding which interpolation algorithm is used.

I would suggest trying both methods and seeing how if affects the outcome. I would also be careful that you dont have overlapping XYZ points of different values. Sometimes points can be hidden underneath others and lead to strange interpolation if the values are different.

Regards,
Toby

Hi,

Which version of Blue Kenue are you using? What steps are you following when you see the problem in Blue Kenue? Can you share a simple and small example .xyz file that has this problem?

Kindly,
Alan

Hello Alan
Thanks for your reply. My problem has been solved by the above two enthusiastic people. It seems that my understanding of software is not deep enough. Lack of understanding of xyz files and the 2D Interpolation.
Thank you very much for your contribution to bluekenue. At present, I use version 3.3.4, which can meet my needs, so I don't update the version.
Thanks again for your reply.
Kindly,
Song

Hello Toby
Thanks for your help, the 2D Interpolation has three interpolation algorithms, that are linear, inversedistance and nearestneighboor. The inversedistance is the default option. So, the value not in the XYZ file is set in the mesh.
I have tried the nearestneighboor option, and that worked.
I didn't realize that the problem was the 2D Interpolation.
Thanks again for your reply.
Kindly,
Song

Hi Song,

It sounds like it's a matter of how much of your XYZ data covers your domain and what interpolation method you are using, assuming you're going with the 2D interpolator, nearest neighbour would -in essence- give different results than linear interpolation for example. (given that your XYZ data is healthy)

P.S. I'd normally extract bathymetry data-for example- that covers my entire domain then use the 2D interpolator (nearest neighbour). If you're still unsure you can simply write a Python script to do the interpolation for you then write your Selafin using PPUTILS toolkit for example.

Hope this helps, Cheers.

Nayef

Hence my questions to the original poster (OP) to find out which version of Blue Kenue is being used and what, exactly, is the problem experienced. Both of those things are still unclear for me, so I cannot provide any help or guidance at this time. The more recent versions of Blue Kenue will likely behave differently than the older versions of Blue Kenue due to the large internal changes that are ongoing.

Kindly,
Alan - Current Blue Kenue Lead Developer

Hi Alan,

Thanks for your reply and clarification.

I will update my Blue Kenue as I have been running the same version for the past year or so- looking forward to see the new developments in the software.

Cheers,
Nayef

Hello Nayef
Following your suggestion, I use the nearest neighbour option in the 2D interpolator. That worked. Thanks for your reply.
In addition, I'm very interested in PPUTILS toolkit. Do you have more information about it? I have tried to understand it, but there is little information about it.
Your reply has helped me a lot. Thanks for your reply.
Kindly,
Song

Hi Song,

I am glad that my response has solved your problem. There's a user manual for the PPUTILS that you can read, but it is generally quite easy to get your head around the functions used if you look at any example script (there are quite a few here on the forum). Let me know if there's a specific task you want to execute, I may be able to help you or point you towards the right direction at least- generally a good use of this toolkit is reading and writing Selafin files.

Cheers,
Nayef