Category Schema (Ontologies)

Setting up your labeling project's ontology on Ango Hub

A project’s category schema (also known as ontology) is the list of labeling tools available in the project.

Ango Hub allows project owners to set the project’s ontology directly from the Category Schema section of the Settings page.

The ontology created from this section is then reflected in the left sidebar of the labeling editor:

How to create a project ontology

From the project’s Settings tab, enter the Category Schema section.

Click on the Add Category button and choose the labeling tool to add. Each tool has a slightly different setup process. See here for a list of all labeling tools available in Ango Hub, and how to add them to your project.

For a guide on how to create nested classifications, see here.

Make categories read-only in specific stages

From Settings > Category Schema, expand a tool or classification. In Read-only Stages, select the Label, Review, or Consensus stages where the category should be locked, then click Save. Selecting a Consensus stage applies to all its branches.

At the selected stages, annotators cannot create annotations with that category or edit, move, or delete existing ones. The annotations remain visible and are exported as usual. A padlock identifies read-only categories in the editor. At other stages, the category remains editable.

Nested classifications follow their parent category's setting. To change or remove a restriction, return to Read-only Stages and update the selection. If a selected stage is deleted from the workflow, it appears as Deleted stage and can be removed from the list.

This setting is not available in 3D MSFT projects. It differs from disabling a category with the category schema's padlock, which only prevents new annotations and still allows existing ones to be edited.

How to copy a project's ontology to a new project

Please check this guide.

Browse and Restore Previous Ontology Versions

From the Settings tab, in the Category Schema section, click on the "History" icon on the top-right to open a history of all workflow versions in the current project.

Category Schema history started being recorded on March 12, 2025. Versions before then had not been saved.

To view a previous version of this project's ontology, click on Preview. To restore it, click on Save while the version you need is previewed.