# compute smooth isovolume for htg input

**URL:** https://discourse.paraview.org/t/compute-smooth-isovolume-for-htg-input/13922
**Category:** ParaView Support
**Tags:** python
**Created:** [February 13, 2024, 10:14am UTC](https://discourse.paraview.org/t/compute-smooth-isovolume-for-htg-input/13922 "2024-02-13T10:14:45Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![sharaborin](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/9de053/32.png) [@sharaborin](https://discourse.paraview.org/u/sharaborin)
#### Post date: [February 13, 2024, 10:14am UTC](https://discourse.paraview.org/t/compute-smooth-isovolume-for-htg-input/13922/1 "2024-02-13T10:14:46Z")

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Hello!  
I have HTG file of bubbles which are multiconnected, I would like to extract from HTG a smooth isovolume and compute each bubble’s volume. I tried this:

1. Apply `HyperTreeGridToUnstructuredGrid`
2. Apply `IsoVolume`  
but it gets a very stepwise result:  
 ![Screen Shot 2024-02-13 at 14.00.01](https://discourse.paraview.org/uploads/default/original/2X/8/86f0b22c671f1b97014e0d9d489245f3af26a744.jpeg)  
Moreover, when I apply `Connectivity2` filter, I get very strange behaviour - Paraview assumes each cell as a separate region:  
 ![Screen Shot 2024-02-13 at 14.06.32](https://discourse.paraview.org/uploads/default/original/2X/9/9f5e056417e1a85181c84580159bc839dd2fa18b.png)

How to make this isovolume to be more smooth and less ‘Minecrafty’?

Surprisingly Contour filter applied to HTG input gives very nice results:

 ![Screen Shot 2024-02-13 at 14.01.05](https://discourse.paraview.org/uploads/default/original/2X/0/015d8b7e7c84459369f402f45a4383db22703fac.jpeg)  
why I can’t do the same for Isovolume?

Best regards,  
Evgenii

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### 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: [February 13, 2024, 10:52am UTC](https://discourse.paraview.org/t/compute-smooth-isovolume-for-htg-input/13922/2 "2024-02-13T10:52:11Z")

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@Charles_Gueunet @tgalland

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### Author: ![wascott](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/w/8e8cbc/32.png) [@wascott](https://discourse.paraview.org/u/wascott)
#### Post date: [February 14, 2024, 4:58am UTC](https://discourse.paraview.org/t/compute-smooth-isovolume-for-htg-input/13922/3 "2024-02-14T04:58:04Z")

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Hi Evgenii,  
What you are seeing is expected behavior. The isoVolume filter will throw cells in or out when the input scalars are Cell type variables. However the isoVolume filter will smoothly clip cells if you are using input scalars that are Point type variables.

Apply the Cell Data to Point Data filter above the isoVolume filter, and use the Point variable from the Cell Data to Point Data filter.

Alan

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### Author: ![sharaborin](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/9de053/32.png) [@sharaborin](https://discourse.paraview.org/u/sharaborin)
#### Post date: [February 14, 2024, 10:37am UTC](https://discourse.paraview.org/t/compute-smooth-isovolume-for-htg-input/13922/4 "2024-02-14T10:37:44Z")

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Hello Alan,  
Thank you very much, that you gave me a hint how to resolve the problem:  
I just converted `HTG` into `HyperTreeGridToDualGrid` it made my cells data into point data. and now isovolume works smoothly!  
And connectivity works properly:

 ![Screen Shot 2024-02-14 at 14.37.11](https://discourse.paraview.org/uploads/default/original/2X/6/6b7829832ee7ae56e52af8716e42b176cb86691c.jpeg)