# LagrangianParticleTracker issue

**URL:** https://discourse.paraview.org/t/lagrangianparticletracker-issue/8507
**Category:** ParaView Support
**Created:** [November 28, 2021, 5:48pm UTC](https://discourse.paraview.org/t/lagrangianparticletracker-issue/8507 "2021-11-28T17:48:10Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![fdekerme](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/f/8dc957/32.png) [@fdekerme](https://discourse.paraview.org/u/fdekerme)
#### Post date: [November 28, 2021, 5:48pm UTC](https://discourse.paraview.org/t/lagrangianparticletracker-issue/8507/1 "2021-11-28T17:48:10Z")

</div>

Hello,  
I am starting to use Paraview 5.10.0-RC1 on Windows10 to do Lagrangian Particle Tracking.  
I start by loading a .vtu file generated with SimVascular, which contains the velocity and pressure map (all\_results\_00\*).

 ![image](https://discourse.paraview.org/uploads/default/original/2X/a/a9b9365e12a29e4b9076ea0323ddb1fd8df649ee.png)

I saw in this post: [https://gitlab.kitware.com/paraview/paraview/-/merge\_requests/1254](https://gitlab.kitware.com/paraview/paraview/-/merge_requests/1254)

that the “Lagrangian Surface helper” and “Lagrangian Seed helper” filters allow respectively to define the properties of the surfaces and the particle source used in the Lagrangian tracking. So I applied these 2 filters.

Then, when I try to use the “Lagrangian Particle Tracker”, I have to select 3 inputs:

1. Flow Input
2. Particle Seeds
3. Surface

In the window that opens, I manage to select the “Flow Input” (= all\_results\_00\*) and the “Surface” (= LagrangianSurfaceHelper1), but I can’t click on “LagrangianSeedHelper1” for the “Particle Seeds” parameter.

How to do it?  
Thanks  
fdekerme

---

<div class="post-metadata">

### Author: ![mwestphal](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mwestphal/32/17_2.png) [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 29, 2021, 9:41am UTC](https://discourse.paraview.org/t/lagrangianparticletracker-issue/8507/2 "2021-11-29T09:41:58Z")

</div>

Did you generate the needed data in the LagrangianSeedHelper ?

I suppose you are using the Matida Integration Model ? It requires the seed to have some values associated to it.

---

<div class="post-metadata">

### Author: ![fdekerme](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/f/8dc957/32.png) [@fdekerme](https://discourse.paraview.org/u/fdekerme)
#### Post date: [November 29, 2021, 3:51pm UTC](https://discourse.paraview.org/t/lagrangianparticletracker-issue/8507/3 "2021-11-29T15:51:39Z")

</div>

I do use the Matida Integration Model.  
Thanks a lot for the solution, I had indeed left some parameters of the LagargianSeedHelper “unchecked”!