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Ango Import Format

Overview of the Ango Hub Label Import Format

Ango Hub allows administrators and project managers to import existing annotations. In order to be imported to the platform, existing labels need to be converted to the Ango Hub Import Format. The following article will provide the format’s specifications, as well as examples of import files.

Common Properties

External ID

The external ID identifies assets in projects.

The external ID of each asset can be viewed from the Assets tab of your project, under the External ID column.

External IDs do not have to be unique. You can have more than one asset with the same external ID.

It is possible to import annotations referencing assets with only their external IDs, as in many exampled below. In this situation, all assets sharing the same external ID will be pre-labeled.

Warning for Video Pre-Annotations

Schema IDs

The Schema ID is a unique identifier for each labeling tool.

To obtain each tool's schema ID, navigate to the Label Set section of the Settings. You will find it when expanding the details of each tool.

Object ID

By default, all objects (annotations) created on Ango Hub, either directly from the platform or by importing them, get assigned a random Object ID used to identify them uniquely.

You may, however, choose to assign a custom object ID to annotations you are importing. This is useful (and necessary) in a number of cases:

  • In video annotations, the object ID allows you to move and track the same annotation between frames.

  • In single and group relations, the Object ID is necessary to relate annotations to one another.

Assigning an object ID manually means that Ango Hub will not create one for the object in question.

Ango Hub will not check nor warn you if you import multiple, different annotations with the same object ID in the same asset or, in the case of videos, in the same frame.

Using the same object ID on more than one object in the same frame can cause unexpected behavior, and may break functionality such as relations.

Unless this is by design, such as tracking an annotation between video frames, always ensure your object IDs are unique to prevent unexpected behaviors.

To add an object ID to any object you are importing, simply add the following line to your object:

For example, a PDF area object with a custom object ID would look like this:

You can add custom Object IDs to all annotation types.

Lock

You can lock certain annotations so that annotators cannot edit them. To do so, simply add "lock":true as a property to an object. For example:

Sample Category Schema

Lock is available for all annotation types, including classifications, except relations. We plan on supporting locking relations soon.

Metadata

  • Add the description metadata to the tools

Sample Category Schema
  • Add the description metadata to the classifications

Sample Category Schema

Page

The "page" field is essential for determining which specific page of an asset the objects should be added to. This field is particularly important when working with assets that contain multiple frames or pages, such as videos, multi-image assets, and DICOM images.

Sample Category Schema

Tools

Bounding Box

x and y refer to the coordinates of the bounding box's top-left corner.

Sample Category Schema

Bounding Box with OCR Text

You may include OCR information such that, when imported, if in the category schema, the "Targeted OCR" toggle was enabled for the bounding box tool:

then you may add the "ocr" field to the bounding box to import, as pre-labels, the OCR contents. Here is an example JSON with the OCR field:

Sample Category Schema

3D Bounding Box

Sample Category Schema

Rotated Bounding Box

Sample Category Schema

3D Rotated Bounding Box

For NRRD assets in the Medical Labeling Editor, use x1, y1, z1, x2, y2, and z2 to define two opposite corners of the box in voxel coordinates. The rotationPlane determines the plane in which rotation is applied: AXIAL, CORONAL, or SAGITTAL.

coordinates1, coordinates2, and measurement are optional. When provided, they should correspond to the NRRD volume's origin, orientation, and spacing.

For the complete asset-import workflow and the rotation-plane axis mapping, see How to Import Rotated Bounding Boxes into NRRD Assets.

Rotated Bounding Box Angles

Rotated Bounding Box Angles
Rotated Bounding Box Angles

Polygon

Sample Category Schema

Polyline

Sample Category Schema

3D Polyline

Sample Category Schema

Segmentation

Segmentations are composed of instances, zones, regions, and holes.

An instance may contain more than one zone. One zone contains exactly one region. A region can contain more than one hole.

Each of the points composing the segmentation is represented as an X/Y coordinate pair. For more information on how X/Y pairs work in the Ango Annotation Format, check out this section. For the way Ango Hub exports segmentation labels, check out this page.

Sample Category Schema

Entity

Entity: Audio Labeling

The start and end properties refer to the seconds elapsed since the start of the audio file.

The optional selection property contains the text associated with the audio entity. The optional tier property assigns the entity to a tier using a zero-based index (0–4). If tier is omitted, the entity is added to the default tier.

Sample Category Schema
Open

Entity: Text Labeling

The start and end properties refer to the character indices of the entity.

The "selection" field is optional for text entities and it is required only to appear on export.

Sample Category Schema
Open

Entity: Video Labeling

The start and end properties refer to the seconds elapsed since the start of the video file.

Sample Category Schema

Point

Sample Category Schema

Circle

Sample Category Schema

PDF

height and width refer to the dimensions of the relevant page of the pdf file.

Sample Category Schema
PDF · 1KB
Open

Brush

Brush

For how to import brush traces with the brush tool, refer to the following page.

Medical Brush

For how to import brush traces with the medical brush tool, refer to the following page.

Message

Sample Message Asset
Sample Category Schema

Angle

Sample Category Schema

Skeleton

Sample Category Schema

Tools with Nested Classifications

Bounding Box / Radio

Sample Category Schema

Any tool and classification available in Ango Hub can be used as a nested classification. The Bounding Box and Radio combination is provided here as an example.

Tool Import for Video and Multi-Image Labeling

Tools: Video Labeling

Video object annotations use keyFrames for frames where the object's geometry is explicitly set. Hub interpolates supported object tools between those keyframes within the object's segments range. See Frame Interpolation for how keyframes, segments, and out-of-view segments appear in the video editor.

Sample Category Schema

Customize Timeline Color

It is also possible to customize the color of a specific interval in the video timeline as follows:

Sample Category Schema

Any tool available in Ango Hub can be used with video assets. The Bounding Box tool is provided here as an example.

Tools: Multi-Image Labeling

Importing annotations for multi-image assets is functionally the same as importing video annotations, with each "image" being a page. Pages start from 0.

Sample Category Schema

Any tool available in Ango Hub can be used with multi-image assets. The Bounding Box tool is provided here as an example.


Classifications

Radio

Sample Category Schema

Checkbox

Sample Category Schema

Single-Select Dropdown

Sample Category Schema

Multi-Select Dropdown

Sample Category Schema

Single-Select Tree

Sample Category Schema

Multi-Select Tree

Sample Category Schema

Text

Sample Category Schema

Nested Classifications

Radio / Radio / Radio

Sample Category Schema

Any classification available in Ango Hub can be used as a nested classification. Nested Radio classifications are provided here as an example.

Multiple Classifications

Sample Category Schema

Any classification available in Ango Hub can be used in multiple question mode. The Radio classification is provided here as an example.

Classification Import for Video and Multi-Image Labeling

Please ensure the "Frame-specific" flag is enabled to add classification labels to each frame, and the "Multiple" flag is enabled to add multiple classification labels for an asset.

Classifications: Video Labeling

Frame-specific video classifications also use keyFrames, but the keyframe value is an answer, not object geometry. The latest previous classification keyframe applies until another keyframe changes the answer, or until the classification's segments range ends. See Frame-Specific Classifications for the UI behavior.

Sample Category Schema

Customize Timeline Color

It is also possible to customize the color of a specific interval in the video timeline as follows:

Sample Category Schema

Any classification available in Ango Hub can be used with video assets. The Radio classification is provided here as an example.

Classifications: Multi-Image Labeling

Sample Category Schema

Any classification available in Ango Hub can be used with multi-image assets. The Radio classification is provided here as an example.


Relations

Single

Direction Options: "straight", "reverse", "bidirectional"

Sample Category Schema

The optional classifications list contains answers to questions configured on the relation. It follows the same nested-classification format used by tools and is supported for both Single and Group relations.

Group

Sample Category Schema

Any tool available in Ango Hub can be used with relations. The Bounding Box tool is provided here as an example.

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