> ## 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.

# Cylindricity

> GD&T Cylindricity evaluation on extracted cylinder features

Cylindricity is a GD\&T tolerance evaluation that quantifies how close a real cylinder is to a perfectly cylindrical form. The Cylindricity Tool in [3D Auto-Dimensioning](/voyager/voyager-auto-dimensioning) runs this evaluation against any cylinder feature extracted from your scan — holes, posts, and similar geometry.

<Warning>
  All measurements should be performed on an [ROI](/voyager/voyager-region-of-interest) that roughly orients your part to the correct orientation. Without a properly oriented ROI, downstream feature evaluation may not align with your part coordinate system.
</Warning>

The Cylindricity Tool is available in [Dimensioning Mode](/voyager/voyager-modes#dimensioning-mode) once Automatic Feature Extraction has produced cylinder features on the parent reconstruction. Every ROI built on that reconstruction inherits those cylinders.

<h2 id="workflow">
  Workflow
</h2>

<Steps>
  <Step title="Select the Cylindricity Tool">
    Choose **Cylindricity** from the Toolbar in Dimensioning Mode.
  </Step>

  <Step title="Choose a cylinder feature">
    Click any cylinder feature on your ROI — holes, posts, and similar geometry. Eligible cylinders highlight on hover.
  </Step>

  <Step title="Set tolerance">
    Enter a **tolerance** value for the evaluation.
  </Step>

  <Step title="Submit">
    Submit to compute the Cylindricity deviation. The result appears as a deviation heatmap on the cylinder along with a pass/fail color-coded label and the standard Cylindricity metric.
  </Step>
</Steps>

<Tip>
  **Tolerance** can be edited after evaluation. Use the Attributes Panel to iterate; the heatmap and pass/fail label update without resubmission.
</Tip>

<h2 id="interpreting-results">
  Interpreting results
</h2>

The Cylindricity result is rendered as a heatmap projected onto the evaluated cylinder, with a numeric Cylindricity value and pass/fail state in the dimension label. The heatmap shows how close the surface is to a perfect cylinder. Use the leader and label controls in the Attributes Panel to adjust label placement so the result is easy to read alongside other dimensions in the scene.

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

* [3D Auto-Dimensioning](/voyager/voyager-auto-dimensioning)
* [Flatness](/voyager/voyager-flatness)
* [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)