# Streamlines not working

**URL:** https://discourse.vtk.org/t/streamlines-not-working/6438
**Category:** Support
**Created:** [August 21, 2021, 2:20pm UTC](https://discourse.vtk.org/t/streamlines-not-working/6438 "2021-08-21T14:20:42Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Tees](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/t/74df32/32.png) [@Tees](https://discourse.vtk.org/u/Tees)
#### Post date: [August 21, 2021, 2:20pm UTC](https://discourse.vtk.org/t/streamlines-not-working/6438/1 "2021-08-21T14:20:42Z")

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So I have a vti file which I read with vtkXMLImageDataReader and then used the vtkImageDataGeometryFilter on the Output. I used the vtkArrayCalculator to get vectors instead of three seperate scalars and on this new vector I calculated the magnitude. I set the vector active as vectors and the magnitude active as scalars. But everything on the pointdata. My glyphfilter is working fine but the streamtracer is not. So I checked the Number of Cells (imageDataGeometryFilter-\>GetOutput()-\>GetNumberOfCells()😉 and this gives me the same amount as Points which I know is wrong. So I think because of the geometry filter the cell structure is lost.  
So here is my question:  
Is there an easy way for me to also get the cells, because I do not want to build them with e.g. Delaunay3D as the original data set has cells?

Thank you for any help in advance!

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### Author: ![Tees](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/t/74df32/32.png) [@Tees](https://discourse.vtk.org/u/Tees)
#### Post date: [August 23, 2021, 2:59pm UTC](https://discourse.vtk.org/t/streamlines-not-working/6438/2 "2021-08-23T14:59:11Z")

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I solved the problem by giving the ImageData with the added arrays, which I calculated, directly into the Streamtracers filter (as input).