> For the complete documentation index, see [llms.txt](https://docs.imerit.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.imerit.net/labeling/labeling-tools/tools/voxel-brush.md).
# Voxel Brush
Overview of the Voxel Brush labeling tool in Ango Hub
The voxel brush labeling tool is a 3D pixel-wise tool to assign voxels on medical imaging assets to certain classes.
{% hint style="info" %}
The Voxel Brush tool is supported across the DICOM and Medical labeling editors.
{% endhint %}
## Adding a Voxel Brush tool to your project
From your project's *Settings* tab, enter the *Category Schema* section. Click on *Add Category*, then on *Voxel Brush*. The tool will be added to your project:
## Voxel Brush Settings
Once the tool has been added to your project, clicking on it wil reveal its settings.
**Schema ID**: This is a unique ID Ango Hub assigns to your tool. It's most important when attempting to import pre-annotations. [Read more about medical pre-annotations here](/data/importing-and-exporting-annotations/importing-annotations/importing-nrrd-annotations.md).
**Title**: A name of your choosing for this tool/class.
**Required**: If enabled, the annotator must have created at least one segmentation with this tool before being able to submit the task.
**Add Classification**: From this section, you may add nested classifications (attributes) to your class. Please refer to [the docs page on the medical labeling editor](/labeling/labeling-editor-interface/medical-labeling-editor.md#tool-class-list) for more information on how to annotate attributes.
## Threshold Editable Area
The in-editor *Editable Area* setting is documented with the other Medical editor brush controls, including *Brush Size*, *Brush Mode*, and *Brush Type*. See the [Medical Labeling Editor](/labeling/labeling-editor-interface/medical-labeling-editor.md#brush-tool) page.
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