# Extracting surface values and shear stress vectors from volume

**URL:** https://discourse.paraview.org/t/extracting-surface-values-and-shear-stress-vectors-from-volume/6986
**Category:** ParaView Support
**Created:** [April 17, 2021, 12:27am UTC](https://discourse.paraview.org/t/extracting-surface-values-and-shear-stress-vectors-from-volume/6986 "2021-04-17T00:27:09Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Mark\_Lohry](https://discourse.paraview.org/user_avatar/discourse.paraview.org/mark_lohry/32/1356_2.png) [@Mark\_Lohry](https://discourse.paraview.org/u/Mark_Lohry)
#### Post date: [April 17, 2021, 12:27am UTC](https://discourse.paraview.org/t/extracting-surface-values-and-shear-stress-vectors-from-volume/6986/1 "2021-04-17T00:27:09Z")

</div>

I have a volumetric flow field consisting of vertex-centered CGNS data, but no specific surface solution data.

1. How does one go about extracting the boundary surfaces with their accompanying values?
2. How can I compute surface shear stress streamlines (aka oil flow lines) on these boundaries?