# Plotting spcth tracer values over time

**URL:** https://discourse.paraview.org/t/plotting-spcth-tracer-values-over-time/238
**Category:** ParaView Support
**Created:** [June 25, 2018, 7:08pm UTC](https://discourse.paraview.org/t/plotting-spcth-tracer-values-over-time/238 "2018-06-25T19:08:19Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![krvorren](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/k/b9e5f3/32.png) [@krvorren](https://discourse.paraview.org/u/krvorren)
#### Post date: [June 25, 2018, 7:08pm UTC](https://discourse.paraview.org/t/plotting-spcth-tracer-values-over-time/238/1 "2018-06-25T19:08:19Z")

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I’m trying to plot pressure as a function of time for tracers in an spcth file.

The data pipeline is set up as follows:

spcth -\> Volume Data (extract cells’ Pressure) -\> Merge Blocks -\> CellDataToPointData -\> PlotSelectionOverTime (PSOT)

I activate the tracer points by displaying them in the render window, and use “Select Points On (d)” to draw a box around the tracers of interest. The points are then highlighted in pink. When I advance time forward, the updated tracer locations are still highlighted.

In the PSOT properties, I toggle “only report selection statistics” off, and then push apply. After a few moments, some plots of pressure vs time are generated, but these plots are very different from the plots I generate from the hscth csv file. The attribute type is also set to “row data.” The other attributes are blank.

I think I discovered the underlying problem by looking at the PSOT in spreadsheet mode: all the points in the point coordinate column were set (seemingly arbitrarily) to 0 0 -2, and not any of the tracer values (which I can also monitor in a separate spreadsheet pane). To further troubleshoot, I used a probe location filter to select the point 0 0 -2 and then generated a PSOT of that point. The same, incorrect pressure vs. time plot was generated. The tracer points move as a function of time, but I need the pressure at those time-varying points, so I can’t just simply pick a static point and plot its pressure.

Is there a way to plot the pressure at these time varying points over time in Paraview?

Misc info:  
Paraview v4.4  
Static mesh, spread over 8 blocks  
I’ve been able to render all relevant geometries in 3D and using the slice filter. I can also plot pressure over a line.  
Please let me know if additional info is needed.

Thanks,  
-Kris

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### Author: ![utkarsh.ayachit](https://discourse.paraview.org/user_avatar/discourse.paraview.org/utkarsh.ayachit/32/39_2.png) [@utkarsh.ayachit](https://discourse.paraview.org/u/utkarsh.ayachit)
#### Post date: [June 26, 2018, 2:30pm UTC](https://discourse.paraview.org/t/plotting-spcth-tracer-values-over-time/238/2 "2018-06-26T14:30:07Z")

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A different route: use the **Resample With Dataset** filter, setting **Input** to the _Volume Data_ and **Source** as the _Tracers_. Now, you have points with field values probed from the CTH volume. Use PSOT on this to generate the plots. In ParaView 5.5, we have **Plot Data Over Time** which can be applied directly to the **Resample…** filter without any need to select points.

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### Author: ![krvorren](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/k/b9e5f3/32.png) [@krvorren](https://discourse.paraview.org/u/krvorren)
#### Post date: [June 26, 2018, 3:19pm UTC](https://discourse.paraview.org/t/plotting-spcth-tracer-values-over-time/238/3 "2018-06-26T15:19:38Z")

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Thanks Utkarsh, that seemed to work. Perhaps a plot of tracers over time would be useful to others on [https://www.paraview.org/Wiki/ParaView\_and\_CTH](https://www.paraview.org/Wiki/ParaView_and_CTH) ?