Interpolation

Interpolation is a process to automatically create instance labels by estimating the location that labels should be created in videos and image sequences. Interpolation uses manual labels as reference points and needs to be run separately for each object instance.

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Note

Object tracking and interpolation both automatically apply labels.

  • Interpolation applies labels in between existing labels.
  • Object tracking uses a single existing label and applies labels to consecutive frames.

All labels automatically created using interpolation are assigned a confidence score (α) of 99%.

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Note

No data is stored on our servers when using interpolation.


Ontologies

Ontology shapeInterpolationTracking
Bounding box
Rotatable bounding box
Polygon
Polyline
Primitive
Keypoint
BitmaskEncord Labs

Simple interpolation

The video tutorial below goes through the basics of using interpolation in the Label Editor.

  1. Create instance labels on at least two non-consecutive frames.

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Tip

The more instance labels are manually added throughout the video, the more accurate the resulting interpolation becomes.

  1. Click the icon on the instance to be interpolated, and click Interpolate.
  1. Interpolation is run between the first and last frames the instance is labeled.

Keyboard shortcut

You can use keyboard shortcuts to run interpolation.

  1. Click the instance label.
  2. Use the Shift + I keyboard shortcut to the run interpolation between the first and last frames the instance is labeled.

Advanced interpolation

  1. Create instance labels on at least two non-consecutive frames.

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Tip

Increase the accuracy of interpolated labels by adding more manual instance labels to different frames as references.

  1. Click the Automated labelling button in the bottom left corner of the label editor to bring up the options for automated labeling. The Tracking and interpolation section is open by default.

  2. The Tracking and interpolation section is open by default.

    • Select Interpolation under the Method heading.
    • Select the object instance(s) you want to interpolate.
    • Interpolation range specifies the range of frames for interpolation.

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Note

Only Organizations on 'Enterprise' pricing can interpolate over a range larger than 1000 frames.

  1. Click Run interpolation to interpolate the selected object instances.

Re-interpolate

Interpolation results can be improved by manually correcting some interpolated labels, and re-running the interpolation.

Enable the Interpolation auto adjustments toggle in the Drawing settings section of the label editor settings. This ensures that only labels with a confidence score (α) of 99% are overwritten in successive interpolations, while manual labels (α = 100%) are kept, and serve as key frames.


This process can be repeated any number of times.

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Note

All labels created using interpolation are always assigned α = 99%.