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This documentation provides a comprehensive guide to using the Label Editor for annotation, covering its components, features, and the display of various elements.

For information on how to label, see our documentation here.

Annotation

Introductory Video Tutorials

The following video goes through the basics of annotating images in the Label Editor.

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

Check out our Video Tutorials page for more introductory videos!

Annotation mode components:


Copy / Paste Labels & Instances

Using the copy and paste features in the Label Editor can significantly save time and effort. Here’s how you can efficiently use these features:

  • Copy: To copy both the label and the instance, use the keyboard shortcut CMD + C on Mac or Ctrl + C on Windows.

  • Paste instance: To paste the copied instance, use CMD + V on Mac or Ctrl + V on Windows. Instances can only be pasted onto a different frame from where they were copied.

  • Paste Label: To paste just the label / shape, use CMD + Shift + V on Mac or Ctrl + Shift + V on Windows. Labels can be pasted onto any frame.


Bulk Label Operations

Fixing incorrect labels is an important step in producing high-quality datasets. With bulk label operations, annotators can merge labels which should really be one instance, or efficiently delete multiple labels in bulk.

Bulk label operations are accessed in the editor menu.

Merge operations

Merge one or more label objects into a single object.

  1. Select all objects to be merged in the Select objects to be merged drop-down menu.
  2. Select the target object in the Select objects to be merged into field.
  3. Click Merge.

Delete operations

Encord lets you perform bulk delete operations as follows:

Remove labels of a specific class:

  1. Select a class to delete from the Select class menu.
  2. Specify the frame range.
  3. Click the Delete button.

Delete all labels within a frame range:

  1. Navigate to the Delete all labels from range section.
  2. Set a range to delete labels from.
  3. Click Delete.

Delete labels below a specified confidence level:

  1. Navigate to the Delete labels below confidence section.
  2. Set the minimum confidence threshold. All labels with a confidence value below this threshold are deleted.
  3. Specify a range of frames to delete the specified labels from.
  4. Click Delete.

Classes

In annotation mode, the Classes section of the Label Editor shows you the available Ontology classes, both objects and classifications. You can create a new instance by either clicking the desired class, or by using the indicated instantiation hotkeys. Learn more about Ontologies in general here or learn more about the details of Ontology structure on Encord.


Instances and Frame labels

The canvas is your labeling area to annotate the instances of the Ontology classes.

  • An instance is a specific occurrence of a class. For example, if you have a class called “Car”, an instance of this class could be “Car(0)”, which might represent a specific black sedan. This single instance can appear in a single frame or a range of frames, and therefore, instances may contain multiple labels across frames. You can think of an instance as a unique object that belongs to a certain class.

  • A frame label is a frame-specific annotation of an instance. For example, the annotation of “Car(0)” on frame 201 is a label. Labels are used to annotate instances in specific frames, providing more detailed information about the instance in the context of that frame.

You can group instances of the same class together using the Group by class button.

Skip or Submit labels

Submit tasks

Labels are applied in the Label Editor. Click the Submit button to submit your labels for review.

All issues need to be resolved before a task can be submitted.

Skip tasks

Users have the option to skip tasks in instances where, for example, the file is blurred, or if they suspect the task was erroneously added.

When a user skips a task, it is automatically unassigned from them, and the task’s status is updated to Skipped. If another task is available, it automatically opens in the Label Editor and is assigned to the user.

  1. Click the Skip button to skip an annotation task.
  1. A dialog appears. Enter a reason for skipping the task - the reason is added as an issue to the task that annotators and reviewers can see. If no reason is entered “This task was skipped” is added by default.

View Annotator Instructions

The Annotator instructions button is available in the top-left corner of the Label Editor if annotation instructions are provided by the Admin or Team Manager.

To learn how to upload annotation instructions click here

Confidence Score

Each instance or label is assigned a confidence score (denoted with the symbol α) that appears next to the label name.

The confidence score is a measure of a machine learning model’s certainty that a given prediction is accurate. The higher the confidence score, the more certain a model is about its prediction.

Manual labels are always assigned α = 100%, while label predictions created via models and automated methods such as interpolation will have a confidence score below 100% (α < 100%).

Models allow you to select a Minimum confidence threshold that determines the lowest confidence that label predictions can have to appear as annotations. It ranges from 0 to 1.

A Minimum confidence threshold of 0.6, as seen in the image above, states that only labels above a confidence score α = 60% will be accepted as labels.


Labels pane

The Labels pane shows all the instantiated objects and classifications for a data unit. Objects are grouped first by class, and sorted by creation time within each class, with earlier objects on top. They are named in an “ABC (0)” format, where ABC is the Ontology class and 0 is the first instance annotation.

  • A: Toggle between showing displaying all labels, or only labels in the current frame.
  • B: Show / Hide details for this instance.
  • C: The range of frames the instances appears on.
  • D: Attributes the object has and the frames they appear on.
  • E: Filter by frame range.
  • F: Sort label instances.
  • G: Search for an instance.
  • H: Show / Hide labels.
  • I: Show / Hide labels for this instance.
  • J: Additional actions. Described below.
  • K: Keyboard shortcut to create a label for this instance.
  • L:Edit attributes for this instance.
  • M: Add a new label for this instance.
  • N: Toggle auto-annotation for SAM.

Click the three dots icon to access additional actions:

Copy URL: Copies the URL for the particular object.

Copy identifier: Each object instance is automatically assigned a unique alphanumeric ID, which can be used to identify it within the project. This ID is sometimes known alternately as a feature hash, instance hash, or instance identifier. For objects and classifications, it may also be known as the object hash or classification hash. Use this button to copy the instance identifier to your clipboard — which may help in workflows using specific instances in source code or for other purposes.

Track from this frame: Initiates single object tracking. This type of automated labeling creates labels for the specified object from the current frame, according to the Single object tracking settings section in the editor settings.

Interpolate: Interpolates this object’s location for a range between specified frames. Please see our documentation on interpolation for more details.

Go to object: Navigate to the specified object in the data asset. If it is present in more than one frame, the first frame the object appears is shown.

Split object track: In some cases, particularly when many objects overlap, labels may be associated with the correct instance in several frames, but later become associated with a different instance. In those cases, use the Split object track feature, which will split the labels from one instance into two at the frame specified.

Change class: Use the drop-down in the modal to change the current class of an instance. You can only switch within classes of the same annotation type. For example, you cannot switch from a bounding box to a polygon.

Delete object: Delete an object from a single frame or a range of frames. To delete labels between frame ranges, move the frame slider to the desired frames, or input the From and To (exclusive) values in the relevant form.

Attributes

The details pane allows you to modify attributes efficiently. For dynamic attributes, use the ‘Preserve chosen state’ feature. When this feature is toggled ‘ON’, any subsequent labels for that instance automatically inherit the same dynamic attribute value as the frame where ‘Preserve chosen state’ was enabled.

See our tutorial on adding attributes for a detailed guide

If you have numerous attributes, use the search bar to quickly find specific attributes or attribute values.


Automated Labeling

Automated labeling includes several techniques to quickly create labels and classifications automatically.

For a more detailed explanation of these features, please visit our automated labeling page.
  1. Click the Automated labeling button to open the Automated labeling panel.
  2. Select the type of automated labeling you want to use.
  3. Run automated labeling for the selected objects.

Alternatively, run object tracking or interpolation on videos, image groups, and image sequences by:

  1. Right-clicking a label.
  2. Selecting Track from this frame to initiate object tracking or auto-segmentation tracking, or select Interpolate to interpolate the selected object instance.

Segment anything model (SAM)

Segment anything model (SAM) allows you to create labels around distinct features in all supported file formats.

  • Click the wand icon within the polygon class.
  • Click on the part of the frame or image you want segmented.
    • Left-click a section you want to add to your label.
    • Right-click a part of the selected area to remove it from the label.
  • Click Add label once the area you want labeled is highlighted.
A step-by-step guide for using SAM can be found here.

Edit polygons and polylines

Encord provides multiple tools to edit polygon and polyline labels after they have been created.

Move vertices:

Click and drag a vertex to move it to a new location.

Adding a polygon or polyline vertex:

You can add more vertices to a polygon after it has been created.

  1. Click the polygon you want to add a vertex to
  2. Click the position along the edge of the polygon you want to add a vertex. Repeat to add as many vertices as necessary.

Removing a polygon or polyline vertex:

You can remove the last vertex by pressing the Backspace key.

Remove vertices from a polygon as follows:

  1. Click the polygon you want to remove vertices from
  2. Right-click a vertex to delete it

Polygon and polyline brush tool:

Use the brush tool to modify the edge of a polygon or polyline in a free-hand manner.

  1. Right-click the polygon you would like to edit.
  2. Click Edit with brush or click the G hotkey. A floating brush tool menu appears.
  3. Adjust the brush size to suit your needs.
  4. Mouse over location you would like to start editing from, and click and hold to start the edit process.
  5. Drag the cursor freely to draw out the new polygon edge let go of mouse to finish editing.

Eraser tool:

Use the eraser tool to remove any part of a polygon in a free-hand manner.

  1. Right-click the polygon you would like to edit.
  2. Click Edit with brush or click the G hotkey. A floating brush tool menu appears.
  3. Select the eraser tool.
  4. Adjust the brush size to suit your needs.
  5. Mouse over location you would like to start editing from, and click and hold to start the edit process.
  6. Drag the cursor freely to draw out the new polygon edge let go of mouse to finish editing.

Editor Canvas Interactions

Shape-specific interactions:

ShapeInteractionsModalities
BitmaskAbility to move (one or multiple)All
Ability to ‘select multiple’ with Shift + clickAll
Draw using polygon ‘pen’All
Panoptic modeAll
PolygonAll
Add vertex with left-clickAll
Remove vertex with right-clickAll
PolylineAll
Add vertex with left-clickAll
Remove vertex with right-clickAll

Right-click interactions:

Track from this frame refers to auto-segmentation tracking for Polygons and Bitmasks, and to object tracking for all other label shapes.
ShapeRight-click InteractionsModalities
Bounding BoxTrack from this frameVideos, image groups, and image sequences only
Bounding BoxInterpolateVideos, image groups, and image sequences only
Bounding BoxSplit object trackAll
Bounding BoxChange classAll
Bounding BoxCopy identifierAll
Bounding BoxDelete objectAll
Bounding BoxCopy URLAll
Rotatable Bounding BoxTrack from this frameVideos, image groups, and image sequences only
Rotatable Bounding BoxInterpolateVideos, image groups, and image sequences only
Rotatable Bounding BoxSplit object trackAll
Rotatable Bounding BoxChange classAll
Rotatable Bounding BoxCopy identifierAll
Rotatable Bounding BoxDelete objectAll
Rotatable Bounding BoxCopy URLAll
PolygonInterpolateAll
PolygonSplit object trackAll
PolygonChange classAll
PolygonCopy identifierAll
PolygonDelete objectAll
PolygonCopy URLAll
PolygonTrack from this frameVideos
PolygonEdit with brushAll
PolygonFreehand edge touchupAll
PolylineTrack from this frameVideos, image groups, and image sequences only
PolylineInterpolateVideos, image groups, and image sequences only
PolylineSplit object trackAll
PolylineChange classAll
PolylineCopy identifierAll
PolylineDelete objectAll
PolylineCopy URLAll
PolylineFreehand edge touchupAll
KeypointTrack from this frameVideos, image groups, and image sequences only
KeypointInterpolateVideos, image groups, and image sequences only
KeypointSplit object trackAll
KeypointChange classAll
KeypointCopy identifierAll
KeypointDelete objectAll
KeypointCopy URLAll
BitmaskInterpolateVideos, image groups, and image sequences only
BitmaskChange classAll
BitmaskCopy identifierAll
BitmaskDelete objectAll
BitmaskCopy URLAll
BitmaskSelect more bitmasks to combineAll
BitmaskTrack from this frameVideos
Object PrimitiveTrack from this frameVideos, image groups, and image sequences only
Object PrimitiveInterpolateVideos, image groups, and image sequences only
Object PrimitiveChange classAll
Object PrimitiveCopy identifierAll
Object PrimitiveDelete objectAll
Object PrimitiveCopy URLAll

Controls Common To Both Modes

The current workflow status is displayed in the top left corner of the label editor.

Editor Layout

Contact support to gain access to custom editor layouts.

You can customize the default Label Editor layout by uploading a JSON file that defines your preferred arrangement. These JSON files can be added in the Project settings and are applied to all tasks in a Project.

Custom editor layouts depend on a file’s client_metadata or their DICOM tags. This means that custom editor layouts only work for files that contain client_metadata or DICOM tags. Watch the video tutorials below to learn how it fits together.

To upload an editor layout:

  1. Navigate to the Project settings.
  2. Click on Layouts.
  3. Click Upload JSON.
  4. Select the JSON file containing the layout you want the Label Editor to have.

JSON file requirements:

The JSON file must follow the JSON schema defined here. The following fields are required:

Complete example

1

Add client metadata to files

Editor layouts are based on DICOM tags for DICOM files or on client_metadata for all other use cases. We provide templates for common mammography layouts based on DICOM tags here.

This example uses client_metadata. The following SDK script can be used to add client metadata to specific data units in a Dataset.

from encord import EncordUserClient
from encord.client import DatasetAccessSettings

# Instantiate Encord client by substituting the path to your private key
user_client = EncordUserClient.create_with_ssh_private_key(
                ssh_private_key_path="<private_key_path>",
            )


# Specify a Dataset to read or write metadata to
dataset = user_client.get_dataset("<dataset_hash>")

# Fetch the Dataset's metadata
dataset.set_access_settings(DatasetAccessSettings(fetch_client_metadata=True))

# Add your file names and client metadata here
layouts = {
  'Image1.jpg': {"encord-EditorGridPosition": "A", 'encord-LayoutGroup': '1'},
  'Image2.jpg': {"encord-EditorGridPosition": "B", 'encord-LayoutGroup': '1'},
  'Image3.jpg': {"encord-EditorGridPosition": "A", 'encord-LayoutGroup': "2"},
  'Image4.jpg': {"encord-EditorGridPosition": "B", 'encord-LayoutGroup': '2'},
  'Image5.jpg': {"encord-EditorGridPosition": "A", 'encord-LayoutGroup': '1'},
  'Image6.jpg': {"encord-EditorGridPosition": "B", 'encord-LayoutGroup': '1'},
  'Image7.jpg': {"encord-EditorGridPosition": "A", 'encord-LayoutGroup': "2"},
  'Image8.jpg': {"encord-EditorGridPosition": "B", 'encord-LayoutGroup': '2'},
  'Image9.jpg': {"encord-EditorGridPosition": "A", 'encord-LayoutGroup': "1"},
  'Image10.jpg': {"encord-EditorGridPosition": "B", 'encord-LayoutGroup': '1'},
  'Image11.jpg': {"encord-EditorGridPosition": "A", 'encord-LayoutGroup': "2"},
  'Image12.jpg': {"encord-EditorGridPosition": "B", 'encord-LayoutGroup': '2'},
}

for dr in dataset.data_rows:
  dr.client_metadata = layouts[dr['data_title']]
  print (dr.title)
  print (dr.client_metadata)
  dr.save()
2

Create a JSON file

Create a JSON for specifying the editor layout that suits your needs.

In the JSON file below:

  • The grid arrangement is configured to display two files side by side in the Label Editor.

  • The gridContent section specifies that tasks in either position (0 or 1) can have client metadata values for encord-EditorGridPosition set to either A or B.

  • The topLevelGridFilter is defined as encord-LayoutGroup, meaning tasks with matching encord-LayoutGroup metadata values are displayed together in the Label Editor, ensuring they appear side by side when they share the same encord-LayoutGroup values.

    {
      "grid": [
        [0],
        [1]
      ],
      "gridContent": {
        "0": {
          "client_metadata_query": {
            "or_conditions": [
              {
                "key": "encord-EditorGridPosition",
                "operator": "=",
                "value": "A"
              },
              {
                "key": "encord-EditorGridPosition",
                "operator": "=",
                "value": "B"
              }
            ]
          }
        },
        "1": {
          "client_metadata_query": {
            "or_conditions": [
              {
                "key": "encord-EditorGridPosition",
                "operator": "=",
                "value": "A"
              },
              {
                "key": "encord-EditorGridPosition",
                "operator": "=",
                "value": "B"
              }
            ]
          }
        }
      },
      "topLevelGridFilter": {
        "client_metadata": {
          "key": "encord-LayoutGroup",
          "operator": "="
        }
      },
      "$schema": "https://raw.githubusercontent.com/encord-team/Annotate/main/editor-layouts/editor_layout_schema.json"
    }
    
3

Create a JSON file

Upload the JSON file to your Project in Encord.

  1. Navigate to the Project settings.
  2. Click on Layouts.
  3. Click Upload JSON.
  4. Select the JSON file containing the layout you want the Label Editor to have.
4

Create a JSON file

Open any task in the task queue of your Project.

The JSON file in this example results in the following Label Editor layout.

We provide end-to-end walkthroughes for how to set up custom editor layouts using:

Editor Menu

Open the editor menu by clicking the menu icon in the top left corner of the Label Editor.

The editor menu contains the following controls:

  • Return to Project - Returns the user to the Project navigation.
  • Save changes - Saves the current state of all labels.
  • View - Allows users to change what information is displayed next to all labels.
  • Bulk label operations (annotation mode only) - Allows the user to perform actions on many labels at once.
  • Automated labeling (annotation mode only) - Lets the user choose between several automated labeling techniques.
  • Dark mode - Toggle dark mode on and off.
  • Keyboard shortcuts - Displays a full list of keyboard shortcuts.
  • Editor settings - Opens the Editor settings.

Editor Header

The Editor header at the top-right of the navigation bar contains buttons and menu items to perform labeling activities as well as manage general app settings and notifications.

IconNameDescription
HelpLinks to the: quick start guide, documentation, learning hub, and Encord support team.
NotificationsShows the current status and history of actions taken in the application. This includes uploading datasets, training models, and exporting labels.
ShareCopies the URL of the asset currently being labeled or reviewed.
Save labelsManually saves labels on the Encord server.
Label Editor settingsSettings controlling your labeling and reviewing experience.
IssuesShows any issues and comments for the current task, such as any objects or classifications marked as Required, or comments added by other users.

Quick Toolbar

A toolbar with handy tools to:

Remove polygon vertices (the scissors tool) is currently not available in review or review-edit mode.
Click the zoom icon again to disable zoom.

Rotate the Label Editor

Click the Rotate toolbar icon on the quick toolbar to bring up a pop-up that enables you to rotate the label editor by using the slider, as shown below.

Click the Rotate 90 degrees icon to rotate the editor in increments of 90 degrees.

Pixelated Scaling

The Pixelated scaling feature enhances the visibility of individual pixels in an image or frame by disabling the browser’s automatic edge smoothing. This increased pixel clarity aids annotators in creating precise, pixel-perfect annotations, thereby improving their annotation accuracy, especially when zooming into an image.

Pixelated Scaling turned onPixelated Scaling turned off

Enable Pixelated scaling by selecting the Adjust filters icon ()in the Quick toolbar and enabling the Pixelated scaling checkbox, as shown below.

Pixelated scaling is a browser-specific feature. The table below shows which types of files Pixelated scaling works for Firefox and Chrome.

File typeChromeFirefox
Image
Image group
Video
Image sequence

Grayscale Filter

The Grayscale filter feature enhances the visibility across an image or frame by applying an RGB grayscale to the image/frame. The filter applies across the pixels of an image/frame using the value for Red, Green, or Blue as a base then converting to grayscale.

You can use the Grayscale filter on images, videos, and DICOM (DICOM and NIfTi) series.

Grayscale Image/Frame

Grayscale DICOM/NIfTi

Media Navigation Controls

The video frame slider lets you quickly scroll through frames in a video asset. Below the frame slider are a range of controls to let you play, skip and navigate through media. Notice that the navigation controls are not displayed in single images files, as well as any media with only 1 frame.

Icon descriptions:

The Time and Frame rate information for each frame is displayed in the far lower right corner.


Comments and Issues

Issues can be added to annotation and review tasks to communicate with other users. All issues contain comment threads relating to the entire task or specific sections of the task. A small notification badge on the Issues icon displays the number of unresolved issues in a task.

Selecting an issue card highlights the label the issue pertains to.

Issues can be added to:

  • The entire task.
  • The current frame (for videos, image groups, and image sequences).
  • A specific location on the frame or task.

Issue threads can be filtered by Resolved and Unresolved issues.

To add a new issue:

  1. Open the Issues pane by clicking the Issues icon.
  2. Click + New.
  3. Choose the part of the task where you want to create the issue.
  4. Add a comment on the issue.
  5. If you selected ‘Pin on canvass’ in step 3, click the desired location on the canvas.
  6. Click Create issue.

To resolve an issue:

  1. Open the Issues pane by clicking the Issues icon.
  2. Click the tick to mark a thread as resolved.

Resolved issues remain visible but can be filtered out. All users can resolve issues.

To delete an issue thread:

  1. Open the Issues pane by clicking the Issues icon.
  2. Click the Ellipsis icon to show more options.
  3. Click Delete thread.

Users can only delete issues that they created. Label rejections cannot be deleted.

Types of Issues:

There are two types of issues: general issues and rejection issues.

  • General issues serve as comments to communicate with other users and can be created at any stage in the Label Editor.
  • Rejection issues are added when a reviewer rejects a task. The reviewer is prompted to provide a reason for the rejection. When rejecting all instances in a frame or image, a rejection issue is created for each rejected label. If a comment is provided, it is applied to all rejected labels within the frame or image.

Use Cases:

  • Ask questions: Annotators and reviewers can ask questions about the task. Admins can use this feedback to improve guidance.
  • Explain task rejection: Reviewers can provide reasons for rejection, helping annotators avoid repeating mistakes.
  • Track unresolved issues: Keep a record of open discussions that need follow-up before finalizing annotations.

Editor Lock

The ‘Editor lock’ is a safety feature we implemented to prevent several people making changes to the same file - annotators labeling, or reviewers reviewing the same data unit.

A warning is triggered in two cases:

  1. When you have the same task open in two different tabs or browser windows:
  1. When a different user is editing the same task:

Turbo mode simplifies the standard annotation workflow, enabling labelers to rapidly assign or confirm attributes. Activate turbo mode and choose an instance from the top-left dropdown menu to set the instance and its relevant attributes.

In turbo mode, the auto-zoom feature automatically focuses the camera on the active instance as you browse through them. You can adjust the zoom manually to get a better view of the instance’s context. The view auto-zooms again when moving to another instance.

Enable turbo mode:

  1. Open the editor settings.
  2. Use the search bar to search for Turbo mode.
  3. Enable the Turbo mode toggle.

WACOM Tablet Support

Our Label Editor fully supports Wacom tablets and pens. You get the best experience if you enable freehand drawing mode.

Label Editor V1 (Legacy)

Label Editor V1 is now deprecated, and we strongly recommend using the new Label Editor. All functionality found in Label Editor V1 is also available in the new Label Editor.

The following actions vary significantly between the legacy Label Editor V1 and the new Label Editor. To see how to perform these in the new Label Editor, see our documentation here.

Adding a polygon vertex - Label Editor V1

To add more vertices to a polygon after it has been created:

  1. Click the polygon you want to add a vertex to
  2. Click the Add vertex icon in the floating window that appears, or use the A hotkey to activate ‘Add vertex mode’
  3. Move the mouse, which should now be in a ’+’ icon, over the edge where you wish to add a vertex. The edge in question should highlight indicating you’ve placed the mouse correctly. Click to place a vertex
  4. Continue placing vertices until you’re satisfied. Press A or click the Add vertex icon on the floating toolbar to turn off add vertex mode

Removing a polygon or polyline vertex - Label Editor V1

To remove vertices from a polygon::

  1. Click on the polygon you want to remove a vertex from.
  2. Click the Remove vertex icon in the toolbar that appears, or use the S hotkey to activate ‘Remove vertex mode’.
  3. Move the cursor to the vertex you want to remove. The cursor should have a ‘cancel’ icon attached.
  4. Click the vertex you want to remove.
  5. Continue removing any vertices until you are satisfied.
  6. Click the icon from step 2 again, or press the S hotkey again to exit ‘Remove vertex mode’.

Freehand edge touchup - Label Editor V1

If you need to modify the edge of a polygon to account for complicated shapes or other requirements, the freehand edge touchup feature allows you edit the edge of the polygon in a free-hand manner, from one vertex to another.

If you need to edit your shape along the edge of the polygon, in between vertices, use the polygon brush tool instead.
  1. Click the polygon you would like to edit.
  2. Click the Freehand edge touchup icon in the floating toolbar that appears, or use the F hotkey to activate ‘freehand edge touchup’ mode.
  3. Mouse over the vertex you would like to start editing from, and click to start the edit process.
  4. Drag the cursor freely to draw out the new polygon edge. Navigate the cursor to the pre-existing vertex you want to finish on, and click to finalize the new edge boundary.