Videos & image sequences

The video below goes through the basics of annotating videos in the Label Editor.

Encord provides comprehensive support for video & image sequence annotations. With the video & image sequence editor, you can:

  • Label using any annotation type.
  • Render videos and image sequences of any length.
  • Track and interpolate objects between frames.
  • Create frame-level and object event classifications.
  • Reduce manual annotations with automation features.

Navigation

Play/pause the video by clicking the play/pause button or by pressing Space. Skip through frames in the video with the Left and Right arrow keys or the forward and backward buttons. The number of frames skipped is determined by the specified Frameskip interval. Frameskip intervals can be set using the predefined values or customized by entering a value in the New input and clicking the + icon.

Control video playback speeds with the playback speed drop-down. 1x is the set playback speed in the below example.

Navigate through the video by scrubbing through or clicking anywhere on the progress bar.

Navigate to a particular frame or timestamp by clicking the compass icon. Replace the value(s) with the desired target and click Go.

Annotation types

Objects are annotated using bounding boxes, polygons, polylines, keypoints or primitives. Frames are annotated using classifications. Instantiating objects or classifications in the video editor generates a UUID that uniquely identifies that instance across a range of frames (i.e., in the temporal dimension). The identifier is sometimes called a "track," with numerical IDs supplementing UUIDs for objects for visual aid.

Object instances can be assigned with static and dynamic classifications (i.e., temporal or "event" classifications that may change over time) as defined in the specified ontology. Static classifications define the global properties of an object (e.g., the car is red and has four wheels) whereas dynamic classifications change with time (e.g., the car is turning right from frames 0 to 100 and left from frame 101 to 150). Dynamic classifications are also sometimes called "actions" or "events".

Supported annotation types & corresponding features are listed in the table below. You can read more about the listed automation features here.

Annotation typeDynamic attributeAutomated trackingInterpolationImport predictionsModel training & inference
Bounding box
Rotatable bounding boxComing soon
PolygonComing soon
PolylineComing Soon
Keypoint
BitmaskN/AEncord LabsN/A
Object primitiveN/AN/AN/A
Frame classificationN/AN/AN/A

Bounding box

Creating a bounding box requires an ontology with a bounding box annotation type. Instantiate a new bounding box instance by clicking on the specified class in the 'Classes' menu, or by using the specified hotkey (e.g., 1, 2, 3).

Instantiating existing bounding box instances (i.e., bounding boxes that should keep the same identifier in preceding or succeeding frames) can be done by clicking on the Highlight icon for the specified object or using the assigned hotkey (e.g., q, w, e).

Bounding boxes can be copy/pasted between frames using cmd (MacOS)/ctrl (Windows) + c to copy the object to the clipboard and cmd/ctrl + v to paste it on the desired frame.

Bounding box instances can be assigned with static and dynamic classifications should they be defined in your ontology:

  • Highlight an object by clicking on it in the editor canvas or by clicking on the Plus icon or start/end frame in the range overview for the specified bounding box
  • Assign a classifications by clicking on the relevant buttons or using the set hotkeys (e.g., q, u).

Tracking

Run automated object tracking by highlighting an object and clicking shift + t on your keyboard.

Object tracking can also be run by selecting the option Track from this frame in the object menu. The number of predicted frames is set to 30 by default. The number of predicted frames can be changed in the 'Settings' drawer in the Single object tracking settings drop-down.

Click the Automated labeling button to open the 'Automated labeling' drawer to run multiple object tracking.

You can read more about automated object tracking here.

Interpolation

Interpolation is run via the 'Automated labeling' drawer. Click the Automated labeling button to open the drawer. Select Interpolation from the drop-down menu, select the desired objects to interpolate, set the interpolation range (i.e., the range of frames) and click the Run interpolation button. Please note that you need a minimum two labels of an instance to run interpolation.

You can read more about interpolation here.

Rotating box

Traditional bounding boxes are great for annotating objects that appear in horizontal or vertical orientation, however, their accuracy may be limited when it comes to annotating objects at an angle. In such cases, use rotatable boxes to
produce more accurate annotations.

Creating a rotatable bounding box requires an ontology with a rotatable box annotation type. Rotatable box labels can be assigned with static classifications should they be defined in your ontology.

Instantiate a new rotatable box label by clicking on the specified class in the 'Classes' menu or using the specified hotkey. Resize rotatable boxes like normal bounding boxes, and then grab the rotation handle to adjust the position until you're satisfied with the annotation's accuracy, as below.


Polygon

Creating a polygon requires an ontology with a polygon annotation type. Enable or disable free-hand drawing mode by pressing d on your keyboard. Polygon coarseness for polygons drawn free-hand is set in the 'Settings' drawer in the Drawing settings drop-down. Instantiate a new polygon instance by clicking on the specified class in the 'Classes' menu or using the specified hotkey (e.g., 1, 2, 3).

A polygon can be closed by double-clicking anywhere on the canvas. Doing so will "snap" creating an edge between the last vertex to the first vertex drawn.

Instantiate existing polygon instances (i.e., polygons that should keep the same identifier in preceding or succeeding frames) by clicking on the Highlight icon for the specified object or using the assigned hotkey (e.g., q, w, e). See the bounding box documentation for visual instructions on how to instantiate existing polygons.

Polygons can be copy/pasted between frames using cmd (MacOS)/ctrl (Windows) + c to copy the object to the clipboard and cmd/ctrl + v to paste it on the desired frame.

Polygon instances can be assigned with static and dynamic classifications should they be defined in your ontology:

  • Highlight an object by clicking on it in the editor canvas or by clicking on the Plus icon or start/end frame in
    the range overview for the specified polygon.

  • Assign classifications by clicking on the relevant buttons or using the set hotkeys (e.g., q,
    u).

See the bounding box documentation for visual instructions on how to assign classifications.

Interpolation

Run polygon interpolation following the instructions for bounding box, which you can find here. Unlike other linear interpolation methods, Encord's polygon interpolation algorithm does not require a matching number of vertices between polygon objects in set keyframes. Our algorithm also allows you to draw polygons in arbitrary directions (e.g., clockwise, counterclockwise, and otherwise).

Editing polygons with the brush tool

You can edit existing polygons with the brush tool. This allows you to create complex shapes in a much faster way than going vertex by vertex. To use the brush tool, select an existing polygon and then click on the brush tool button. This will show the brush tool settings panel where you can choose brush or eraser and change its size. Once you are done editing, click the "x" to go back to the label editor. Use the scissors tool if you'd like to remove vertices.

Polyline

Creating a polyline requires an ontology with a polyline annotation type. Enable or disable free-hand drawing mode by pressing d on your keyboard. Polyline coarseness for polylines drawn free-hand is set in the 'Settings' drawer in the Drawing settings drop-down.
Instantiate a new polyline instance by clicking on the specified class in the 'Classes' menu or using the specified hotkey (e.g., 1, 2, 3).

Polylines can be copy/pasted between frames using cmd (MacOS)/ctrl (Windows) + c to copy the object to the clipboard and cmd/ctrl + v to paste it on the desired frame.

Complete a polyline by double-clicking anywhere on the canvas.

Instantiate existing polyline instances (i.e., polylines that should keep the same identifier in preceding or succeeding frames) by clicking on the Highlight icon for the specified object or using the assigned hotkey (e.g., q, w, e). See the documentation for visual instructions on how to instantiate existing polylines.

Polyline instances can be assigned with static and dynamic classifications should they be defined in your ontology:

  • Highlight an object by clicking on it in the editor canvas or by clicking on the Plus icon or start/end frame in the range overview for the specified polyline.

  • Assign a classification by clicking on the relevant buttons or using the set hotkeys (e.g., q, u).


Keypoint

Creating a keypoint requires an ontology with a keypoint annotation type. Instantiate a new keypoint instance by clicking on the specified class in the 'Classes' menu or using the specified hotkey (e.g., 1, 2, 3).

Instantiate existing keypoint instances (i.e., keypoints that should keep the same identifier in preceding or succeeding frames) by clicking on the Highlight icon for the specified object or using the assigned hotkey (e.g., q,
w, e). See the bounding box documentation for visual instructions on how to instantiate existing keypoints.

Keypoints can be copy/pasted between frames using cmd (MacOS)/ctrl (Windows) + c to copy the object to the clipboard and cmd/ctrl + v to paste it on the desired frame.

Keypoint instances can be assigned static and dynamic classifications should they be defined in your ontology:

  • Highlight an object by clicking on it in the editor canvas or by clicking on the Plus icon or start/end frame in
    the range overview for the specified keypoint.

  • Assign classifications by clicking on the relevant buttons or using the set hotkeys (e.g., q,
    u).

See the bounding box documentation for visual instructions on how to assign classifications.

Automated tracking

Run automated keypoint tracking following the instructions for bounding box, which you can find here.

Interpolation

Run keypoint interpolation following the instructions for bounding box, which you can find here.


Primitives

Creating a primitive (f.k.a. skeleton templates) requires an ontology with a primitive annotation type. Use primitives to templatize shapes (e.g., 3D cuboids, pose estimation skeletons ) commonly used by your annotation team.

Instantiate a new primitive instance by clicking on the specified class in the 'Classes' menu or using the specified hotkey (e.g., 1, 2, 3).

Instantiate existing primitive instances (i.e., primitives that should keep the same identifier in preceding or succeeding frames) by clicking on the Highlight icon for the specified object or using the assigned hotkey (e.g., q, w, e). See the bounding box documentation for visual instructions on how to instantiate existing primitives.

Primitives can be copy/pasted between frames using cmd (MacOS)/ctrl (Windows) + c to copy the object to the clipboard and cmd/ctrl + v to paste it on the desired frame.

Primitives allow you to define properties of edges defined in your template as visible, occluded, or invisible. Toggle the edge property settings for a primitive by highlighting the primitive and clicking the Show controls button.

Primitive instances can be assigned with static and dynamic classifications should they be defined in your ontology:

  • Highlight an object by clicking on it in the editor canvas or by clicking on the Plus icon or start/end frame in the range overview for the specified primitive.

  • Assign classifications by clicking on the relevant buttons or using the set hotkeys (e.g., q, u)
    See the bounding box documentation for visual instructions on how to assign classifications.

Automated tracking

Run automated primitive tracking following the instructions for bounding box, which you can find here.

Interpolation

Run primitive interpolation following the instructions for bounding box, which you can find here.


Segmentation masks / Bitmasks

Bitmasks allows you to create labels using a brush tool to select parts of an image. This can be useful when creating labels for vessel outlines, or labelling topologically separate regions belonging to the same frame classification.

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Creating a mask segmentation requires an ontology with the Bitmask annotation type.

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Tip

Existing Bitmask labels can be updated using the brush tool, threshold brush, and eraser tools.

Brush tool

When you select your Bitmask annotation type, the brush tool will be selected by default. You can adjust the size of the Bitmask brush tool using the slider in the Bitmask popup, as seen in the screenshot above.

The brush tool can be selected by clicking the icon, or by hitting f on your keyboard while the popup is open.

When your label is ready, click Apply label, or press Enter.

Threshold brush

The Threshold brush tool enables you to set a threshold that determines the parts of the image or frame that is labeled by the Bitmask. This means only parts of the image within the set range are labeled when selected using the Threshold brush tool.

Three different kinds of threshold can be selected:

  • Intensity: Only pixels within the set intensity value range are labeled.
  • RGB: Only pixels within the set red, green, and blue range are labeled. The range for each color can be set separately.
  • HSV: Only pixels within the set hue, saturation, and value range are labeled.

To select the threshold brush, click the icon, or press g on your keyboard while the popup is open. Adjust the size of the brush tool, as well as the range of intensity values you would like to include in your labels using the two sliders on the popup, as seen in the screenshot below.

When your label is ready, click Apply label, or press Enter.

Threshold preview

The Threshold preview toggle allows you to see the parts of an image that correspond to the set threshold. This allows you to preview which parts of the image are labeled when a Bitmask label is applied. There are three types of Threshold preview:

  • Transparent: the parts of the image that will be included in the Bitmask label are shown, the rest of the image is black.
  • B/W: the parts of the image that will be included in the Bitmask label are shown in white, the rest of the image is black
  • Inverted: the parts of the image that will be included in the Bitmask label are shown in black, the rest of the image retains its original color.

Eraser

The Eraser tool allows you to erase parts, or the entirety of your Bitmask selection if the Apply label button has not been clicked yet.

To select the threshold brush, click the icon, or press h on your keyboard while the popup is open.

Bitmask overlap management

It is possible to prevent a Bitmask label from being overlapped by subsequent Bitmasks after the label is created. Use the toggle in the Labels section of the Label Editor to set the overlap behavior.

Choose between the following settings:

  • **Can be drawn over** - if drawn over, any part of the image beneath the existing Bitmask that falls within the specified threshold range will be included in the next label.
  • Cannot be drawn over - no part of the image covered by this Bitmask will be included in any other Bitmask labels.

  • Must be drawn over - if drawn over, any part of the Bitmask label will be included in the new Bitmask, regardless of threshold values set.

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Note

The Must be drawn over setting for Bitmask overlap is only available to select customers. Please contact [email protected] for more information.

Updating Bitmask labels

To update a Bitmask label:

  1. Click the Bitmask label you would like to edit.
  2. Select either the brush, threshold brush, or eraser tool and make your changes.
  3. Press Enter or click the button in the Bitmask popup.

Moving Bitmasks

Bitmask labels can be moved to another location after being created.

  1. Click the Bitmask label you want to move.
  2. Click and drag the Bitmask to the desired location.
  3. Release the Bitmask to confirm the new location.

Frame classification

Creating frame classification(s) requires an ontology with a classification annotation type. Frame-level classifications consider the frame as a whole, not the objects' localization. Instantiate a frame-level classification instance by clicking on the specified class in the 'Classes' menu or using the specified hotkey (e.g., 1, 2, 3).

Set the desired start and end frame by clicking the Set start to current and Set end to current buttons or using the set hotkeys c and v, respectively. Click the This frame button or the x hotkey to set the slider to only the current frame (e.g., frame 100). Add additional ranges by clicking the Add range button or pressing the n hotkey to add a frame range (e.g., if a car enters and leaves the frame throughout a video). Click the Save button or the m hotkey to save the instance. Use the This frame & save button or the z hotkey to classify and save the results for a single frame quickly.

Encord currently supports radio, checklist, and free-form text input classification types.

Edit existing classification instances by clicking on the Plus icon for the specified instance in the 'Classifications' pane in the 'All instances' section.


Dynamic attributes

Encord supports dynamic attributes for all object annotation types (i.e., bounding box, polygon, polyline, keypoint, and primitives).

Highlight the desired object to assign dynamic classifications. Dynamic classifications are recognized by the Dynamic tag next to the given feature in the ontology. Dynamic classifications are only applied in the frames specifically indicated but can be edited in ranges if they span multiple frames.

Attribute propagation & Keyframes

The video tutorial goes through the basics of working with Dyanmic Attributes in the Label Editor.

Keyframe-based attribute propagation allows you to mark frames in which dynamic attributes change value as keyframes, and then bulk apply attributes between the keyframes. This saves time when applying dynamic attribute to object instances across many frames.

Using keyframe-based attribute propagation

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You need an ontology with a dynamic nested attribute to use keyframe-based attribute propagation.

  1. Apply object labels to all relevant frames.

  2. Add the dynamic attribute to the label in the first frame that the object appears in.

  3. Navigate to the point of the video or image sequence where the dynamic attribute changes value, and apply the attribute to the object here.

  4. Use the icon highlighted above, or the keyboard shortcut Shift + L to set keyframes on frames where the attribute changes value.

  5. Use the icon highlighted above, or the keyboard shortcut Shift + P to apply attribute values to all frames following a keyframe, matching the value set in the keyframe.

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All frames in between keyframes have to be labeled for attribute propagation to work.

You can also add or remove keypoints manually:

  • Use the icon, or the keyboard shortcut Shift + A to add a keypoint to a frame.
  • Use the icon, or the keyboard shortcut Shift + S to remove a keypoint from a frame.

Frame labels tab

The Frame labels tab will show all instances with a label in the current frame, and will be empty when there are no labels in a given frame.


Editor timeline

The Editor timeline is a visualization of the times and durations at which objects and instances appear within a video. Every object added by an annotator will automatically appear on the timeline at the point in time when it is added. The colors of an object on the timeline match those used to label the objects in the video.

For example, the timeline in the image above shows that:

  • The 'lake' object was added at the start of the video (0:00), and is present in all frames in the first 7 seconds of the video.

  • There are 3 separate instances of a 'boat' object - the times in the video at which they appear, and the duration of the annotations.

The timeline moves as the video is played, so that the location of the cursor on the timeline always corresponds to the frame currently being displayed.

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Tip

Clicking an object or instance on the timeline brings up the first frame on which it appears, and displays the instance label's classification properties.

The editor timeline is visible by default when using the label editor. It can be re-sized or completely removed by dragging it either up or down, as seen below.

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The editor timeline is available in both the Annotation and Review states for videos.

Advanced Editor timeline

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Note

The advanced Editor timeline is only available to select customers. Please contact [email protected] for more information.

The advanced Editor timeline has all the abilities of the regular Editor timeline - familiarize yourself with the documentation for the Editor timeline before continuing.

Selecting objects and instances

One or more objects and instances can be selected using the timeline. Simply click an object or instance on the timeline to select it. To select multiple objects or instances, click while holding down the Shift key.

Alternatively select a object or instance by right clicking and choosing Select.

Moving objects and instances

Once objects and instances have been selected they can be moved to the top or the bottom of the timeline to suit your needs.

  1. Select the instances and objects you want to move.
  2. Right click your selection.
  3. Hover on Move when moving a single object or instance, and Move all when moving multiple objects or instances.
  4. Select To top or To bottom depending on whether you want to move the object(s) and instance(s) to the top or the bottom of the timeline.

Merging instances on the timeline

Multiple instances of the same object can be merged into a single instance of your choice, provided they don't appear on the same frame.

  1. Select the instances you want to merge.
  2. Right click your selection.
  3. Hover on Merge into.
  4. Select the instance you want to merge your selection into.

Linking object instances

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Object instances are linked using Relation attributes, which are set up in the Ontology. See our documentation on Relation attributes to learn more.

  1. Create both instance labels. In this example a chicken and its' wing have been labeled using bounding boxes.

  2. Click the Edit classifications button for the object with the Relation attribute. In the example this object is the wing, as seen below.

  1. Click the Set relation... bar and select the instance you want to link the selected instance to. In our example the chicken and the wing appear on the same frame, and therefore appear under the This frame heading. Instances in different frames will appear under the heading Rest.
  1. Click Done. The instances are now linked. This is shown in the Instance labels section with the name of the linked instance being displayed.

Automation

Supported annotation types and available automation features are listed in the table below.

Annotation typeDynamic attributeAutomated trackingInterpolationImport predictionsModel training & inference
Bounding box
Rotatable bounding boxComing soon
PolygonComing soon
PolylineComing Soon
Keypoint
BitmaskN/AEncord LabsN/A
Object primitiveN/AN/AN/A
Frame classificationN/AN/AN/A

Automated object tracking

Encord's automated object tracking feature uses a proprietary algorithm that runs without using a representational model. The algorithm works by matching pixel information inside the annotation to subsequent pixels in neighboring frames.

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Tip

Read more about object tracking and how to use it in our step-by-step guide.


Interpolation

Encord's interpolation feature uses a proprietary linear interpolation algorithm that runs without using a representational model or matching pixel information in neighboring frames.

Our interpolation algorithm has been built with pragmatic usage in mind. For example, unlike other linear interpolation methods, Encord's interpolation algorithm does not require a matching number of vertices between objects in set keyframes. Our algorithm also allows you to draw object vertices in arbitrary directions (e.g., clockwise, counterclockwise, and otherwise).

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Tip

Use our step-by-step guide to learn how to use the interpolation feature, and how to improve interpolation results using re-interpolation.


Import model predictions

Encord's Python SDK & APIs allow you to import model predictions programmatically. Importing model predictions helps to pre-annotate your data to save annotation costs.


Models

The Models tab is where you attach and manage models for automated labeling to your Project. Encord's Apollo allows you to build models for automated data labeling.

Please see our documentation on models here.