# Sample Surfaces

*Sample surfaces are imported surface geometries used for extracting and analyzing flow field data at specific locations within the simulation domain.*

## Overview

Sample surfaces allow you to use arbitrary surface geometries in the flow field to capture detailed flow properties. Unlike slices (which are planar and created in the GUI), sample surfaces can conform to complex shapes imported from external files, providing flexibility for flow analysis in regions of interest.

Sample surfaces are accessed through the **Resource** panel (see [Top Bar](../01.introduction/03.workbench-layout/04.top-bar.md#resource)), alongside geometry resources.

```{note}
A sample surface is a monitoring entity: a non-manifold surface used to measure quantities at internal locations. It is distinct from a *baffle face*, which is a non-manifold input face that the GeometryAI mesher removes or thickens during meshing preprocessing (see [Remove baffle faces](../02.simulation-setup/02.mesh/02.mesh-parameters.md#remove-baffle-faces)). The key difference: a baffle face is part of the input geometry processed by the mesher, whereas a sample surface is **not represented in the mesh** (the flow solution is sampled onto it).
```


## Importing Sample Surfaces

To import a sample surface:

1. Open the **Resource** panel
2. Select the **Sample surface** tab
3. Click the **Import** button
4. Select a surface geometry file to import
5. The imported sample surface will appear in the **Sample surfaces** section of the Entities browser

### Supported Formats

Sample surfaces can be imported from standard surface mesh formats (e.g., STL, CGNS, UGRID).


```{seealso}
- [Grab-and-go snippet](../../python_api/grab_and_go_snippets/import_sample_surface.rst) — minimal python API working example.
```