Ontologies

Instructions for creating and managing your ontologies in your Labelbox workspace.

This guide provides a comprehensive overview of how to create, manage, and optimize your ontologies within Labelbox to ensure your team works with precision and your models are built on a foundation of quality.

What is an ontology?

Think of an ontology as the master blueprint for your data labeling tasks. It defines exactly what your team should be labeling and how they should label it. An ontology consists of features which are:

• Objects: The items you want to identify (e.g., Car, Pedestrian, Tree).
• Classifications: Questions to categorize the data (e.g., Is the image blurry?, What time of day is it?).
• Relationships: Connections between labeled objects (e.g., a person is walking a dog).

Every project and model in Labelbox requires an ontology. When a labeler works on a task, the ontology appears as their set of tools in the labeling editor.

Create your first ontology

Follow these steps to create a new, reusable ontology for your projects.

1. Go to the Schema tab in your Labelbox workspace and select Ontologies.
2. Click the Create button to start the setup process.
3. Choose the type of data this ontology will be used for (e.g., Image, Video, Text). This is a critical step. The media type determines which annotation tools (bounding box, polygon, etc.) will be available for you to add.
4. In the setup screen, provide the following:

Item	Description
Name	This is the name you will use to look up your ontology later. Give your ontology a descriptive name (e.g., “Vehicle Identification - US Roads”).
Objects	Objects in this context are specific items you want to identify and annotate in your data (e.g., car, person, building) Labelbox will search for existing features by name to encourage reuse. Click + Add to create or reuse object features.
Classifications	Classifications are questions or attributes used to categorize or describe objets or the overall data (e.g., Is the traffic light red or green?, What is the weather condition?). Click + Add to create or reuse classification tasks.
Relationships	Relationships are connections or interactions that exist between different labeled objects (e.g., a driver is inside a car). Click + Add to define relationships between your objects.

5. Click Create ontology to complete the setup.

Ontology size limit

Visit our Limits page to view the maximum allowed features per ontology.

Attach an ontology to a project

To use an ontology, you must first attach it to a project.

1. Go to the project’s Settings tab.
2. Find the Label editor section and click Edit.
3. Use the dropdown menu to select and attach your desired ontology.

Warning: Changing an ontology can invalidate existing labels

If you edit an ontology that is already in use, annotations created with the old version will remain, but they may no longer align with the new structure. For example, if you add a new required classification, old labels will not have this information, which can impact data exports and quality metrics like consensus.

Clone an ontology

If you want to build upon an existing ontology without affecting projects that use it, create a copy. This creates a duplicate, independent version that you can freely modify.

1. Create a new project.
2. From the project overview, select Set up ontology.
3. Select the ontology you want to copy from the list.
4. Click Create copy and select.
5. Name your new ontology.

Your new ontology will automatically be attached to the project you just created.

Adding or archiving features in the copied ontology will not impact the original ontology from which the copy was created.

However, modifications made to a specific feature included in the ontology will cascade through all ontologies containing the feature, including the original ontology.

Edit your ontology

Navigate to Schema > Ontologies and click on the ontology you wish to modify. To edit your ontologies, you can:

Add a new feature: Click the + button under Objects or Classifications and search for the feature you want to add. Remember, this will not automatically require you to rework existing labels.

Reorder features: In the edit screen, simply drag and drop the features into the new order you want them to appear for labelers.

Archive a feature: If a feature has already been used to create annotations, you cannot delete it, but you can archive it. Archiving removes the feature from the labeler’s view but preserves all historical data.

1. Go to the Schema tab.
2. Click Ontologies and select the ontology you want to edit.
3. Click Edit.
4. Select the feature you wish to remove.
5. Click the settings icon in the top right corner to remove or archive the feature. If a feature has never been used, you can safely remove it permanently.

You can unarchive a feature at any time from the ontology editor to make it available for labeling again.

Archived features are still included in exports

To ensure that all annotation data can be exported from our application, archiving a feature will not remove it from the export file. If you do not plan on using that data in your downstream systems, you will need to ignore those annotations based on feature schema ID.

Delete your ontology

To keep your workspace clean, you can filter for and delete all unused ontologies and features from the Schema tab.

1. Go to the **Schema **tab.
2. Select Show : Unused.
3. Click Delete unused ontologies.

You can do this from the Schema tab by adjusting the filter to “Show: Unused”. When this option is selected, you will see a new button to delete all unused features or ontologies.

Deleting an ontology is permanent and cannot be undone.