# Measure exact the alpha.phase 1 level

**URL:** https://discourse.paraview.org/t/measure-exact-the-alpha-phase-1-level/2611
**Category:** ParaView Support
**Created:** [September 24, 2019, 10:04am UTC](https://discourse.paraview.org/t/measure-exact-the-alpha-phase-1-level/2611 "2019-09-24T10:04:36Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![cory.quammen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/cory.quammen/32/11193_2.png) [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [September 27, 2019, 10:34pm UTC](https://discourse.paraview.org/t/measure-exact-the-alpha-phase-1-level/2611/6 "2019-09-27T22:34:05Z")

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Instead of **Python Annotation** only, you can use **Programmable Filter** to compute both volume and surface area from the full and extracted dataset.

First, click the original dataset in the _Pipeline Browser_, then Ctrl-click the **Extract Surface Filter** , so you have two selected filters in the browser. Now add a **Programmable Filter** with the following script:

```python
from paraview import vtk

height = sum(volume(inputs[0]) * (alphaphase1 >= 0.8)) / sum(area(inputs[1]))
output.FieldData.append(height, "height") 

```

Finally, add a **Python Annotation** with _Array Association_ set to “Field Data” and _Expression_ set to `height[0]`.

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