> ## 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

> Author a Feature Set in Dimensioning Mode with a detail slider and live readouts

Feature Extraction is how you **author a Feature Set** for [3D Auto-Dimensioning](/voyager/voyager-auto-dimensioning). A Feature Set is the collection of geometric primitives Voyager measures to and from: **planes**, **cylinders**, and a **full-part mesh** used by [Profile](/voyager/voyager-profile).

Extraction is no longer a single fixed-detail click. In [Dimensioning Mode](/voyager/voyager-modes#dimensioning-mode), the **Features** toolbar button opens a workflow with a detail slider and four live readouts that update as you drag, so you can see what you will get before you run it.

<video controls className="w-full aspect-video" src="https://mintlify.s3.us-west-1.amazonaws.com/lumafield/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-a-feature-set-is">
  What a Feature Set is
</h2>

Dimensional features are geometric primitives extracted from full-resolution reconstruction data. Extraction runs **once on the parent reconstruction**. Every [ROI](/voyager/voyager-region-of-interest) built on that reconstruction inherits the resulting Feature Set. Adding or editing an ROI does not re-run extraction.

The returned features are:

* **Planes**
* **Cylinders**
* A **full-part mesh** used for Profile Analysis

Those primitives — automatic and [manually authored](/voyager/voyager-manual-feature-authoring) — are the inputs to Direct Dimensions, Flatness, Cylindricity, Datums, and Profile.

<Note>
  Extraction works best on monomaterial, low-attenuation parts. Mixed-material assemblies and high-attenuation alloys may produce noisier features; reach out to Lumafield to discuss your application.
</Note>

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

<Steps>
  <Step title="Open Dimensioning Mode">
    Switch to [Dimensioning Mode](/voyager/voyager-modes#dimensioning-mode) and select the parent reconstruction (or an ROI that inherits from it).
  </Step>

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

  <Step title="Set the detail slider">
    Drag the detail slider. Four readouts update live: **Resolution**, **Voxel size**, **Smallest radius**, and **Thinnest wall**. Use them to judge what the Feature Set will resolve before you commit.
  </Step>

  <Step title="Choose a setting that matches the part">
    Finer detail is the right choice for small pins, thin rims, and threaded holes. Coarser detail is faster and is often enough when you mainly need large planes. Watch **Smallest radius** and **Thinnest wall** against the smallest geometry you care about.
  </Step>

  <Step title="Submit">
    Run extraction. When it finishes, planes, cylinders, and the full-part mesh appear in the Viewport and Data Panel. Child ROIs on that reconstruction show the same Feature Set.
  </Step>
</Steps>

<Tip>
  Work with Lumafield to integrate Auto-Dimensioning into [Recipes](/recipes/recipes-intro) for fully automated GD\&T runs across a fleet of scans.
</Tip>

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

[Manual Feature Authoring](/voyager/voyager-manual-feature-authoring) requires a Feature Set extracted with **algorithm v20 or newer**. On an older extraction, the Features controls used for authoring are greyed out and a tooltip explains why.

To enable authoring on an older Project, **re-run Feature Extraction** on the parent reconstruction. Re-extracting replaces the previous Feature Set on that reconstruction. After a v20 (or newer) run, authored features behave like automatic ones: selectable, measurable, and usable as datums.

Feature Extraction v20 and later also produce more complete surfaces, which yields cleaner full-part [Profile](/voyager/voyager-profile) evaluations.

<h2 id="when-to-author">
  When to author features by hand
</h2>

Automatic extraction is the starting point. Use [Manual Feature Authoring](/voyager/voyager-manual-feature-authoring) when you need control over thin rims, disconnected components, small patches that mimic CMM probe points, or any surface the automatic Feature Set missed or over-included.

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

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