# Stream Tracer - from surface
**URL:** https://discourse.paraview.org/t/stream-tracer-from-surface/2996
**Category:** ParaView Support
**Created:** [November 18, 2019, 4:11pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996 "2019-11-18T16:11:34Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@Dec](https://discourse.paraview.org/u/Dec)
#### Post date: [November 18, 2019, 4:11pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/1 "2019-11-18T16:11:34Z")
Hi All,
Apologies if this has been covered, however I was unable to find it if it is.
I would like to know how to seed streamlines from a surface, specifically any inlet within a solution.
To simplify, if we have a rectangular section with an inlet at one end, is it possible to seed stream lines from that surface rather than using the spherical point location or line source?
Thanks
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 18, 2019, 4:20pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/2 "2019-11-18T16:20:44Z")
Yes, StreamTracerWithCustomSource.
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### Author:  [@Dec](https://discourse.paraview.org/u/Dec)
#### Post date: [November 18, 2019, 4:49pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/3 "2019-11-18T16:49:33Z")
> [@mwestphal](#):
>
> StreamTracerWithCustomSource
Thanks Mathieu,
I had not seen it, this software is huge and powerful…
much appreciated!
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### Author:  [@Dec](https://discourse.paraview.org/u/Dec)
#### Post date: [November 18, 2019, 5:56pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/4 "2019-11-18T17:56:34Z")
What are the main contributors to causing it to calculate the very slowly? my grid is less than 1\*10^6 cells, albeit with 3 individual inlets and 1 single outlet…
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 19, 2019, 9:30am UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/5 "2019-11-19T09:30:30Z")
How many seeds (points) do you have in your custom source ?
Are you running ParaView in parallel ?
If you want to have a quick look into the flow, you may want to use the StreamLines representation :
- Tools -\> ManagePlugin -\> StreamLinesRepresentation -\> Load
- Create a new view
- Use the new StreamLine representation instead of surface/outline/etc
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### Author:  [@Dec](https://discourse.paraview.org/u/Dec)
#### Post date: [November 19, 2019, 11:38am UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/6 "2019-11-19T11:38:09Z")
Yes I see now the influence of the number of seed points is substantial.
I have tried to use the Mask Points function (which can reduce the # of points??) in the workflow;
- celldata.vtu
- CellDatatoPointData
- Mask Points
- StreamTracerWithCustomSource
- Not sure of the flow here, do you select input source as CellDatatoPointData or MaskPoints?
- And also do you select Seed Source as your custom seeding surface?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 19, 2019, 1:13pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/7 "2019-11-19T13:13:03Z")
> Not sure of the flow here, do you select input source as CellDatatoPointData or MaskPoints?
Input should be celldata.vtu, Seed source should be MaskPoints
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### Author:  [@Dec](https://discourse.paraview.org/u/Dec)
#### Post date: [November 19, 2019, 1:21pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/8 "2019-11-19T13:21:01Z")
Uh so do the mask points filters have to be applied to each surface of interest “for seeding” individually?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 19, 2019, 1:25pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/9 "2019-11-19T13:25:21Z")
Maybe the easiest way would be to append all your seed surface together using AppendDataSet filter, then use MaskPoint on that.
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### Author:  [@momentumv](https://discourse.paraview.org/u/momentumv)
#### Post date: [November 26, 2019, 7:25pm UTC](https://discourse.paraview.org/t/stream-tracer-from-surface/2996/10 "2019-11-26T19:25:15Z")
Late to the party, but I’ve sometimes used a decimate/resample instead of MaskPoint