Table of Contents

Multi-frame point

Alex Cota Updated by Alex Cota

For customers annotating very detailed objects and their movement in a video, the multi-frame point tool provides more granularity than the multi-frame bounding box tool. With the multi-frame point tool, you can apply a point to a series of frames and adjust the position of the point across the frame sequence. You can also add nested radio and checklist classifications to point objects in your ontology.

Video point tool

Import your video data

First, create your project in Labelbox and ensure your videos are in .mp4 format.

By default, you'll be able to load videos with up to 2000 frames and 30fps. Please contact support if you need to work with larger videos.

You have two options for adding your video files to Labelbox:

  1. Direct upload files via app or via Python SDK.
  2. Import URLs via JSON or CSV. Note: private data will require signed URLs. To see the JSON video import format, see Import via JSON - Video import sample.
    1. Upload JSON or CSV containing URLs via app.
    2. Bulk import URLs in JSON via the GraphQL API.
    3. Bulk import URLs in JSON via the Python API.

Configure point for video

Project setup
  1. Create a project.
  2. Select "editor" as your label editor.
  3. From the "Configure editor" window, click "Add object" and name the object class.
  4. Select "Point" as your labeling tool.
  5. Click "Confirm".
  6. Click "Complete setup".
Nested classifications

The nested classification types supported for multi-frame point are radio and checklist only. Text and dropdown classification types are not supported. In the configure editor step, you can create nested classifications within your point objects by clicking the right carrot next to the object. You’ll also have the option to make the classification question(s) required.

How it works

There are two main components to creating multi-frame points:

  • The selected frames to persist the point
  • The point position on the frames

A keyframe is a frame on the timeline where a change occurs. Interpolated (tweened) frames are the ones between two keyframes. Labelbox uses interpolation to incrementally adjust the position of a point between two keyframes.

When a keyframe is created, a white dot on the frame distinguishes keyframes from all other frames.

Select frames

Apply a point at a single keyframe

By default, when you apply a point when a single frame is selected, that point will persist at the same position across all subsequent frames until the end of the video.

Apply a point to a set of frames

When you select a set of frames on the timeline and apply a point to the selection, the point will persist at the same position across each frame in the selection.

Toggle on/off a point

When an item in the video goes out of frame then reappears 1 or more frames later, use the toggle icon to turn on/off the point for that item. Note: Toggle on/off is only possible when a single frame is selected. You cannot toggle the point on or off when multiple frames are selected.

Copy/paste a point

When you copy and paste a point from one frame to another, it will be pasted at the same position. A new point instance is created out of the copied object and, by default, the point will persist until the last frame in the video. Note: Copy/paste on multiple frames at a time is not supported.

Edit a point position

Edit a point

When you select one or multiple frames, you can adjust the position of a point in the frame selection. When these changes are made, Labelbox treats the selected frame(s) as a new keyframe or group, and interpolates the point’s position between any preceding and following keyframes.

Change position mid-sequence

When you change the position of the point in the middle of the sequence, Labelbox uses interpolation (also known as tweening) to incrementally adjust the point to its new position. The updated point position will persist until the end of the sequence.

Insert point between interpolated frames

When you adjust the position of a point between two already interpolated keyframes, Labelbox will interpolate the point to adjust for the newly inserted keyframe.

Delete point

Right click on the point to delete the entire instance of the point in every frame it appears. You can also do this with the backspace key.

Create instances

When a video is loaded in the labeling interface, your labelers can use the same class for more than one annotation with the following steps:

  1. Select the point class from the "Tools" panel.
  2. Select the same point class again.
  3. Draw the next instance of the point.

Export labels

For instructions on how to access your multi-frame point labels and a sample Point label export, see our docs on Video export formats.

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