> ## Documentation Index
> Fetch the complete documentation index at: https://support.lumafield.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Feature Extraction

> Fit a feature set to a volume for Dimensioning

Feature Extraction fits surfaces to a volume and stores them as a **feature set**. [3D Auto-Dimensioning](/voyager/voyager-auto-dimensioning) measures those surfaces. It does not measure raw voxels.

In [Dimensioning Mode](/voyager/voyager-modes#dimensioning-mode), **Features** opens a workflow. A detail slider and live readouts update as you drag, so you can see what the feature set will resolve before you run it. Choose **Single material** or **Multi-material** for the surfaces you want.

<video controls className="w-full aspect-video" src="https://mintcdn.com/lumafield/ZWRoFQpofIViz7Vs/images/mfa_featureset.mp4?fit=max&auto=format&n=ZWRoFQpofIViz7Vs&q=85&s=04cf131469669cb5569e422a83e286f2" data-path="images/mfa_featureset.mp4" />

*Author a Feature Set: open Features, set detail with the slider, and review Resolution, Voxel size, Smallest radius, and Thinnest wall before you run extraction.*

<h2 id="what-comes-back">
  What comes back
</h2>

Extraction runs **once on the volume you select**. Every [ROI](/voyager/voyager-region-of-interest) on that volume inherits the feature set. Editing an ROI does not re-run it.

A feature is one of:

* **Plane**
* **Cylinder** — including large cylinders and threads
* **Cone**
* **Fillet**
* **Chamfer**
* **Sphere**

Features whose area falls under the cutoff are inactive. Inactive features stay out of datum and GD\&T pickers.

[Manual Feature Authoring](/voyager/voyager-manual-feature-authoring) adds planes and cylinders by hand. It does not author cones, fillets, or chamfers.

<Warning>
  Results on a new extraction look different from an older feature set, including on parts you have already checked. Re-run the datums and GD\&T checks that depend on the replaced features.
</Warning>

<h2 id="materials-and-contrast">
  Materials
</h2>

**Single material** finds features on the densest material and ignores other surfaces, such as a fixture.

**Multi-material** takes a material count. Voyager finds features on the densest materials and ignores the rest. **All** finds features on every surface.

Metal scans produce fewer false surfaces than earlier extractions, and an uploaded grey-scale volume can return a usable feature set. A mixed assembly is still harder than a single material. If a surface you need is missing, raise the material count, then look at what noise came with it.

**Minimum contrast** is in Advanced. Leave it alone unless a faint surface is missing or a noisy one should be ignored.

<h2 id="run-feature-extraction">
  Run Feature Extraction
</h2>

<Steps>
  <Step title="Open Dimensioning Mode">
    Switch to [Dimensioning Mode](/voyager/voyager-modes#dimensioning-mode).
  </Step>

  <Step title="Open Features">
    Choose **Features** in the Toolbar and select the volume.
  </Step>

  <Step title="Set detail">
    Drag the detail slider. **Resolution**, **Voxel size**, **Smallest radius**, and **Thinnest wall** update as you drag. Finer detail resolves small pins, thin rims, and threads. Coarser detail is faster when you mainly need large planes.
  </Step>

  <Step title="Set materials">
    Choose **Single material** for one part, or **Multi-material** and set how many of the densest materials to keep. **All** includes every surface.
  </Step>

  <Step title="Submit">
    Run extraction. Planes, cylinders, and the other surfaces appear on the volume. Click the feature set in the tree to read the settings it was run with.
  </Step>
</Steps>

<h2 id="algorithm-v20">
  Algorithm v20 or newer
</h2>

[Manual Feature Authoring](/voyager/voyager-manual-feature-authoring) requires algorithm **v20 or newer**. On an older extraction the authoring controls are greyed out and a tooltip explains why. Re-run extraction to replace that feature set.

<h2 id="related-pages">
  Related pages
</h2>

* [3D Auto-Dimensioning](/voyager/voyager-auto-dimensioning)
* [Manual Feature Authoring](/voyager/voyager-manual-feature-authoring)
* [Datum Definition](/voyager/voyager-datums)
* [Flatness](/voyager/voyager-flatness)
* [Cylindricity](/voyager/voyager-cylindricity)
* [Profile](/voyager/voyager-profile)
* [Voyager Modes](/voyager/voyager-modes)
* [Voyager Release Notes](/platform/voyager-release-notes) and [Monthly Highlights](/platform/monthly-highlights)


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