[jiejie]

Dear Paraview users

I am trying to use the median filter from Paraview to remove some noise / smooth out the data. However, the median filter is alway in grey, which cannot be applied to the data set I have. My data is in the plt format. I am wondering if anyone used the median filter?

Thank you.
Jie

[jiejie]

I played around with different types of data. I found the median filter works with the vti data format. The question is how to use the median filter if the data is a in different format, e.g. plt format?

[wyldckat]

Quick answer: The problem is not due to the file format itself, the problem is the data structure it's in.

After loading the "vti" or "plt" file, with it selected in the "Pipeline Browser", go to the tab "Information" below and check what type of data structure it's defined as. For example, as shown in the attached image.

[jiejie]

Originally Posted by wyldckat

Quick answer: The problem is not due to the file format itself, the problem is the data structure it's in.

After loading the "vti" or "plt" file, with it selected in the "Pipeline Browser", go to the tab "Information" below and check what type of data structure it's defined as. For example, as shown in the attached image.

Hi wyldckat

Thanks for your advice. The vti data has the type of image (uniform rectilinear grid) where as my tecplot data has the type of multi-block dataset. The question is whether it is possible to convert one to the other so that the median filter can be applied to the data set I want or is there a type of median filter that can be applied to the multi-block data set?

Thanks
Jie

[wyldckat]

Hi Jie,

I did some looking into this and it seems that perhaps you're confusing "Median" with "Temporal Average"?

I ask this because:

• The filter "Median" is available only for image processing.
• As for "Temporal Average", I'll quote the answer I found:
  

  Originally Posted by tonyuprm

  One should use the filter "temporal statistics" under "Temporal". This will calculate the average of all the time steps.

Beyond this, my guess all that it's left is to use the "Programmable Filter" along with the Python modules "numpy" and "scipy", which would require you to search for ways to do some noise filtering with numpy/scipy!?


Of course the other way to actually use the Median filter is for you to use the menu "File -> Save Screenshot", save as an image and then load it again to apply the filter... although this doesn't sound very healthy...

Best regards,
Bruno

[jiejie]

Originally Posted by wyldckat

Hi Jie,

I did some looking into this and it seems that perhaps you're confusing "Median" with "Temporal Average"?

I ask this because:

• The filter "Median" is available only for image processing.
• As for "Temporal Average", I'll quote the answer I found:
  

Beyond this, my guess all that it's left is to use the "Programmable Filter" along with the Python modules "numpy" and "scipy", which would require you to search for ways to do some noise filtering with numpy/scipy!?


Of course the other way to actually use the Median filter is for you to use the menu "File -> Save Screenshot", save as an image and then load it again to apply the filter... although this doesn't sound very healthy...

Best regards,
Bruno

Hi Bruno

Thanks for you quick reply again. I used to use python script to postprocessing my Tecplot data. However, I found it is a bit slow to re-load the data into a 3D array and apply a 3D median filter. Hence, I tried to do it in Paraview. Then, I realised that the median filter from Paraview can only be applied to the images. I am in the process to use the programable filter. However, I am still at the stage of learning how to use the python command to access the data in Paraview. Any advice will be appreciated.

Regards,
Jie

[wyldckat]

Hi Jie,

A few good references:

• A very complete ParaView User Guide (for 4.3.1) is available for download here: http://www.paraview.org/download/
• http://www.paraview.org/Wiki/ParaView/Python_Scripting
• http://www.paraview.org/Wiki/Python_Programmable_Filter

For the rest, I suggest Googling for:

paraview python

And possibly:

paraview numpy

Good luck! Best regards,
Bruno