# Trying to extract upper and lower surface Cp values from a slice

**URL:** https://discourse.paraview.org/t/trying-to-extract-upper-and-lower-surface-cp-values-from-a-slice/7085
**Category:** ParaView Support
**Created:** [April 27, 2021, 6:15pm UTC](https://discourse.paraview.org/t/trying-to-extract-upper-and-lower-surface-cp-values-from-a-slice/7085 "2021-04-27T18:15:20Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![aarafat](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/a/43a26b/32.png) [@aarafat](https://discourse.paraview.org/u/aarafat)
#### Post date: [April 27, 2021, 6:15pm UTC](https://discourse.paraview.org/t/trying-to-extract-upper-and-lower-surface-cp-values-from-a-slice/7085/1 "2021-04-27T18:15:20Z")

</div>

Hi,

I am working on creating a plot of Cp against x, I have extracted the surface, put in the equation of Cp and sliced it, but I am not really sure how to differentiate between the upper and lower surface values.

 ![Screenshot 2021-04-27 at 7.11.58 pm](https://discourse.paraview.org/uploads/default/original/2X/5/592f3f28f2f1e2d8e03bd868235c56030802d66a.png)

This my Cp contour and I am trying to recreate something like this…

![Screenshot 2021-04-27 at 1.56.40 pm](https://discourse.paraview.org/uploads/default/original/2X/1/11fe188b29af6b2b760f5b484187a9366097d79d.png)

Any help would be much appreciated!