Skip to main content
The Polygon tool draws arbitrary polygon shapes to outline objects with complex boundaries. It provides more precise object delineation than bounding boxes while remaining straightforward to use.

​
When to Use

Use polygons when:
  • You need precise object outlines for instance segmentation or panoptic segmentation
  • Objects have irregular shapes that bounding boxes cannot represent well
  • You need a balance between precision and annotation speed
  • The downstream model requires polygon annotations (e.g., Mask R-CNN with polygon input)
Consider a different tool when:
  • Rough localization is sufficient — use the Bounding Box tool
  • You need pixel-perfect boundaries on complex textures — use the Segmentation tool with SAM assist
  • The object has very simple rectangular shape — bounding boxes are faster

​
Usage

  1. Press P or select the Polygon tool from the toolbar
  2. Click to place the first vertex
  3. Continue clicking to add vertices along the object boundary
  4. Close the polygon by:
    • Clicking the first vertex (a highlight appears when hovering)
    • Pressing Enter
  5. Assign a label

​
Editing Vertices

  • Move a vertex: Click and drag any vertex handle
  • Add a vertex: Click on an edge midpoint (shown as a smaller handle)
  • Delete a vertex: Right-click a vertex and select Delete Vertex
  • Move entire polygon: Click inside the polygon and drag

​
Shortcuts

ShortcutAction
PActivate the Polygon tool
Enter or double-clickClose the polygon
EscapeCancel current polygon
Delete / BackspaceDelete selected polygon
Ctrl+Z / ⌘ZUndo
Ctrl+Shift+Z / ⌘⇧ZRedo

​
Common Mistakes

  • Too few vertices on curves: Curved edges look jagged with too few vertices — add more points to smooth them out
  • Too many vertices on straight edges: Straight edges only need two endpoints; extra vertices add noise without improving accuracy
  • Not closing the polygon: Forgetting to close leaves the annotation incomplete — always close with a click on the first vertex or press Enter
  • Cutting corners on occluded boundaries: Trace the visible boundary carefully; do not shortcut across occluded areas

​
Advanced Tips

  • Double-click to finish the polygon (equivalent to pressing Enter)
  • Press Escape to cancel the current polygon and start over
  • For very complex shapes, consider using the Segmentation tool with SAM instead — it can be faster for highly irregular boundaries
  • Zoom in on tight areas before placing vertices for better precision
  • In video mode, polygon vertices can be tracked across frames for object tracking workflows
  • Bounding Box — For quick rectangular localization
  • Segmentation — For pixel-level masks (especially with SAM assist)
  • Polyline — For open line annotations (lanes, paths)
  • Keypoint — For pose estimation with skeleton structures