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-   -   paraview streamline length (http://www.cfd-online.com/Forums/paraview/125120-paraview-streamline-length.html)

sawyer89 October 19, 2013 07:55

paraview streamline length
 
Hi,
does anybody know how to compute the length of a streamline in paraview?I need to compute tortuosity.
Thank you in advance.

wyldckat October 19, 2013 11:58

Greetings Alessandro and welcome to the forum!If you only have a single streamline and you want to calculate the total length, then:
  1. Apply the "Integrate Variables" filter.
  2. A spreadsheet should appear on the right of the screen.
  3. On that spreadsheet, change the option "Attribute" to "Cell Data".
  4. One of the columns should be named "Length".
Best regards,
Bruno

sawyer89 October 24, 2013 10:37

Thanks a bunch Bruno! :) Finally I've succeded to compute tortuosity strting directly from the velocity field, without the aid of paraview. Anyway it will be useful in future!
Best regards
Alessandro

Rosa Zhou February 25, 2016 21:19

Quote:

Originally Posted by sawyer89 (Post 457796)
Hi,
does anybody know how to compute the length of a streamline in paraview?I need to compute tortuosity.
Thank you in advance.

Hello Alessandro,
Could you tell me how to calculate tortuosity by paraview step by step? I only know how to draw the streamlines. Thank you!

Best,
Rosa

Quote:

Originally Posted by wyldckat (Post 457814)
Greetings Alessandro and welcome to the forum!If you only have a single streamline and you want to calculate the total length, then:
  1. Apply the "Integrate Variables" filter.
  2. A spreadsheet should appear on the right of the screen.
  3. On that spreadsheet, change the option "Attribute" to "Cell Data".
  4. One of the columns should be named "Length".
Best regards,
Bruno

Hello Bruno,
If I got a bunch of streamlines, how to get the length of each one?

Best regards,
Rosa

wyldckat March 28, 2016 16:06

1 Attachment(s)
Greetings Rosa,

Quote:

Originally Posted by Rosa Zhou (Post 586903)
If I got a bunch of streamlines, how to get the length of each one?

Sorry for the late reply, but only today did I finally manage to take a quick look into this.
The quickest solution I could figure out will only allow the calculation of each individual line length within ParaView:
  1. Apply the filter "Threshold" to the streamtracer entry on the Pipeline Browser.
  2. Choose in "Threshold" to use the scalar "SeedIds" and the values minimum and maximum should both be the same, for example both should be 0 for the first line.
  3. Then apply the filter "Integrate Variables".
  4. On the spreadsheet view that appeared, select the Cell Data mode and it will show the line length.
Attached is an image that shows this in practice.


As for doing this automatically for all lines, you will have to export the data from the streamtracer (menu File -> Save Data) to a CSV file and do the calculations with some other application, such as LibreOffice Calc.


Best regards,
Bruno

Rosa Zhou March 29, 2016 21:39

Quote:

Originally Posted by wyldckat (Post 592032)
Greetings Rosa,


Sorry for the late reply, but only today did I finally manage to take a quick look into this.
The quickest solution I could figure out will only allow the calculation of each individual line length within ParaView:
  1. Apply the filter "Threshold" to the streamtracer entry on the Pipeline Browser.
  2. Choose in "Threshold" to use the scalar "SeedIds" and the values minimum and maximum should both be the same, for example both should be 0 for the first line.
  3. Then apply the filter "Integrate Variables".
  4. On the spreadsheet view that appeared, select the Cell Data mode and it will show the line length.
Attached is an image that shows this in practice.


As for doing this automatically for all lines, you will have to export the data from the streamtracer (menu File -> Save Data) to a CSV file and do the calculations with some other application, such as LibreOffice Calc.


Best regards,
Bruno

cool, the step2 is really useful! can it show the straight-line distance for the NO.0 seed as well?
Thank you Bruno ^_^

wyldckat April 2, 2016 18:34

Quote:

Originally Posted by Rosa Zhou (Post 592302)
can it show the straight-line distance for the NO.0 seed as well?

Quick answer: AFAIK, to do that you will have to do with an external application, as I mentioned in the other post:
Quote:

Originally Posted by wyldckat (Post 592032)
you will have to export the data from the streamtracer (menu File -> Save Data) to a CSV file and do the calculations with some other application, such as LibreOffice Calc.


Zango Ankrios April 29, 2016 11:13

Streamline Length
 
2 Attachment(s)
Hello Bruno,

I found this discussion about streamline length. However, I do not manage to get it.

Here is my problem.
I imported a .vtk file of a streamline from star ccm+.
I applied the Integrate Variables Filter to it. On the spreadsheet you mentionned, I changed the option "Attribute" to "Cell Data".
Yet, I do not have the "Length" Column.

Do you know the reason ?

Than you in advance

Best regards,
Zango


Ps : pdf files are actually screenshots of paraview

wyldckat May 1, 2016 19:00

Quick question: Can you share an example VTK file with which this can be reproduced?
Because the problem seems to be that you applied the "Integrate Variables" filter to something that is not a polygonal line and is instead a mesh.

Perhaps you exported a tube-shaped streamline?

Zango Ankrios May 2, 2016 03:31

1 Attachment(s)
Thank you for your quick answer.
I enclosed the vtk file for which I wanted to apply the "Integrate Variables" filter to.
I do not know whether it is a tube shaped streamline or a polygonal line.

wyldckat May 8, 2016 15:49

1 Attachment(s)
Quote:

Originally Posted by Zango Ankrios (Post 597639)
Thank you for your quick answer.
I enclosed the vtk file for which I wanted to apply the "Integrate Variables" filter to.
I do not know whether it is a tube shaped streamline or a polygonal line.

Quick answer: It's a a polygonal surface, as shown in attachment, also known as a "ribbon".

You will need to change the way you created the streamlines. If you cannot, then I'm not even sure how we can extract only one of the long edges of the surface... :(

Zango Ankrios May 10, 2016 04:40

Ok thank you for your answer :)


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