Annotation Tips and Tricks

Annotation Tips and Tricks

This tutorial aims to act as a guide to show all the simple and advanced tools the LabelEngine offers.

The functionality described is as follows:

  • Start/Select a polygon
  • Zoom
  • Delete
  • Discard polygon progress
  • Turbo mode
  • Add point to existing polygon
  • Delete brush
  • Push brush
  • Magnetic mode
  • Grouping polygons
  • Copy/Paste polygon
  • Select all instances of a class
  • Cutting tool
  • Editing label layer
  • AI auto segmentation
  • Predictive labelling tool
  • General tips

Keyboard Shortcuts Overview

Start/Select a polygonClickStart or select a new polygon
Start/End a polygonSpacebarStart or end a new polygon
ZoomScroll WheelZoom in or out at the mouse pointers location
DeleteDel (fn+Del on Mac)Deleted selected polygon or point
DiscardEscDiscards current in-progress polygon
UndoCtrl+zUndo last action (point placement or polygon creation)
Select MultipleCtrl+ClickSelect multiple polygons
Turbo modeHold Shift+ClickActivates Turbo Mode
Add pointaAdds a point to the selected polygon
Delete brushdActivates/Deactivates delete brush
Push brushpActivates/Deactivates push brush
Magnetic ModemActivates/Deactivates magnetic mode
GroupgGroups selected polygons
Copy PolygonCtrl+cCopies the selected polygon
Paste PolygonCtrl+vPastes a previously copied polygon from the clipboard
Select All InstancesCtrl + Shift + ClickSelects all class instances on the image of the polygon clicked on
Keyboard Shortcuts

General Tips

To control the brush radius for push and delete tools open the settings menu then increase or decrease the “Brush Radius”

To change the frequency of points in “SHIFT” (Turbo) Mode increase or decrease the “Turbo Place Point Distance (Pixels)” setting

For fine detail annotations or high-resolution images, the loupe zoom multiplier in the top left’s zoom can be controlled in settings

Basic Tools

Starting a polygon:
Click or Spacebar on an image.

Ending a polygon:
Spacebar to end an image.

Select a polygon:
Click on the polygon
Ctrl+Click to select multiple polygons

Zoom in or out:
Adjust mouse Scroll wheel or 2 finger scroll on the trackpad

Delete a polygon or point:
Del while polygon or point selected

Discard polygon process:
Esc while a polygon is in progress


Turbo Mode

Hold Shift+Click to activate Turbo Mode – Turbo Mode, places polygons following the path of the pointer at a set distance apart (frequency of points customizable in settings)

Turbo Mode
Add Point to Polygon

Select polygon then click ‘a‘ on the keyboard near the edge of a polygon to add a point to the polygon where the pointer is

Adding A Point
Delete Brush

Click ‘d‘ on the keyboard to activate/deactivate the delete brush

Delete Mode
Push Brush

Click ‘p‘ on the keyboard to activate/deactivate the push brush

  • Note it can be used on single or multiple polygon points and the brush size is customisable in the settings
Push Mode
Magnetic Mode

Click ‘m‘ on the keyboard to activate/deactivate magnetic mode. Magnetic mode snaps the next polygon to the nearest polygons edge.
Note: Shift was held to snap to the entire edge quickly while in magnetic mode

Magnetic Mode
Group polygons
  • Select all target polygons (must all be the same label) with a Ctrl+Click
  • Click “g” on the keyboard
  • The polygons should now be grouped.
  • To reverse a grouping. Select the group and click “g
Group Polygons
Cut a Polygon

Ctrl+Click on the 2 polygons

Click Splice tool

Cutting a Polygon
Change Label Layer

Select the target polygon.

Click layer front of layer back icon in the toolbar

Editing Polygon Layer


AI Auto Segmentation

To Use AI Auto Segmentation, Click the Auto Segmentation Icon
Now create a 4 pointed polygon, each point being at the extreme most points of the target object.

  • The Highest Point
  • The Lowest Point
  • The Leftmost Point
  • The Rightmost Point

Finally, wait for the polygon to snap into place.

AI Auto Segmentation
Predictive Labelling

To use the predictive labeling first endure AI Endpoints have been added to the project.

Then navigate to the “Predictions Tab” on the right panel. Select your prediction threshold (how confident the model must be to place a polygon)

Click “Predict”

Predictive Labelling
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