Annotation Tools

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Overview

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Bounding Box Tool

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Usage

1. Press B or select the Box tool from the toolbar
2. Click and drag from one corner to the opposite corner
3. Release to complete the box
4. Select a label from the label dropdown

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Editing

• Move: Click inside the box and drag
• Resize: Drag any edge or corner handle
• Adjust precisely: Use the properties panel to enter exact pixel values for x, y, width, and height

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Tips

• Draw tight boxes that closely fit the visible extent of the object
• Include partially occluded objects — the box should cover the visible portion
• For overlapping objects, draw separate boxes for each
• Hold Shift while dragging to constrain the box to a square

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Polygon Tool

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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

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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

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Tips

• Use more vertices on curved edges for smoother outlines
• Use fewer vertices on straight edges to keep the annotation clean
• 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

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3D Cuboid Tool

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Usage

1. Press C or select the Cuboid tool from the toolbar
2. Click in the point cloud to place the cuboid center
3. A default cuboid appears at the clicked location
4. Adjust the cuboid:
   • Drag corners: Resize length, width, and height
   • Drag edges: Adjust individual dimensions
   • Drag center handle: Reposition the cuboid
   • Drag rotation handle: Rotate around the Z-axis (yaw)
5. Assign a label

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Adjusting Dimensions

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Multi-Camera Verification

1. Draw or adjust the cuboid in the 3D view
2. Check the camera panels to verify the projection aligns with the object
3. Adjust if the 2D projection does not match

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Tips

• Fit to points: Size the cuboid to tightly enclose the object’s points
• Ground contact: Align the bottom face with the ground plane
• Orientation: Match the cuboid heading to the object’s direction of travel
• Use camera views to verify depth and height, which are harder to judge in the top-down 3D view
• Press R to reset the 3D camera view if you lose orientation

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Semantic Segmentation Tool

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Usage

1. Press M or select the Segmentation tool from the toolbar
2. Choose a label from the label panel
3. Use one of the sub-tools:

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Brush

• Click and drag to paint a mask region
• Adjust brush size with [ (smaller) and ] (larger)
• Hold Shift to paint in a straight line between two clicks

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Eraser

• Press X to toggle eraser mode
• Click and drag to erase mask pixels
• Same size controls as the brush

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Fill

• Click inside an enclosed region to flood-fill it with the current label
• Useful for filling the interior of a polygon outline

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SAM Assist

• Press S to activate SAM mode within the segmentation tool
• Click on the object to generate a mask
• Refine with positive and negative clicks
• Press Enter to apply the mask

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Tips

• Start with SAM for the initial mask, then refine edges with the brush and eraser
• Use the eraser at a small size for precise edge cleanup
• Zoom in (+ or scroll) for fine detail work along object boundaries
• Each label gets a distinct color overlay, configurable in the label panel
• Toggle mask visibility with H to see the underlying image

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Polyline Tool

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Usage

1. Press L or select the Polyline tool from the toolbar
2. Click to place the first point
3. Continue clicking to add points along the line
4. Press Enter to finish the polyline (it remains open, unlike a polygon)
5. Assign a label

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Editing

• Move a point: Click and drag any point handle
• Add a point: Click on a segment midpoint
• Delete a point: Right-click a point → Delete Point
• Extend the line: Select the endpoint and click to add more points

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Use Cases

• Lane markings and road boundaries
• Curb edges
• Fences and barriers
• Trajectory paths

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Tips

• Keep points consistent in spacing for smooth lines
• Use more points on curves, fewer on straight sections
• In video mode, polylines can be tracked across frames like any other annotation

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Classification Tool

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Usage

1. Press K or select the Classification tool from the toolbar
2. The classification panel appears (or the label panel switches to classification mode)
3. Select one or more labels that describe the image/frame:
   • Weather: sunny, rainy, foggy
   • Scene: highway, urban, parking lot
   • Time of day: daytime, nighttime
4. Classifications are saved automatically when you navigate to the next item

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Multi-Label vs. Single-Label

• Single-label: Only one classification can be selected (radio buttons)
• Multi-label: Multiple classifications can be selected (checkboxes)

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Tips

• Use classification for metadata that applies to the entire image, not to specific objects
• Combine with object-level annotations: classification for scene context, boxes/polygons for objects
• In video sequences, classification can vary per frame (e.g., lighting changes)

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Keypoint Tool

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Usage

1. Press J or select the Keypoint tool from the toolbar
2. A skeleton template appears based on your project’s keypoint definition
3. Click to place the first keypoint
4. Place subsequent keypoints following the skeleton structure
5. The viewer draws connections between keypoints automatically based on the skeleton definition
6. Assign a label

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Skeleton Definitions

• Keypoint names: e.g., nose, left_eye, right_eye, left_shoulder
• Connections: which keypoints are connected by edges
• Visibility: each keypoint can be marked as visible, occluded, or not present

{
  "keypoints": [
    "nose", "left_eye", "right_eye", "left_ear", "right_ear",
    "left_shoulder", "right_shoulder", "left_elbow", "right_elbow",
    "left_wrist", "right_wrist", "left_hip", "right_hip",
    "left_knee", "right_knee", "left_ankle", "right_ankle"
  ],
  "connections": [
    ["left_shoulder", "right_shoulder"],
    ["left_shoulder", "left_elbow"],
    ["left_elbow", "left_wrist"],
    ["right_shoulder", "right_elbow"],
    ["right_elbow", "right_wrist"],
    ["left_hip", "right_hip"],
    ["left_hip", "left_knee"],
    ["left_knee", "left_ankle"],
    ["right_hip", "right_knee"],
    ["right_knee", "right_ankle"],
    ["left_shoulder", "left_hip"],
    ["right_shoulder", "right_hip"]
  ]
}

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Editing Keypoints

• Move a keypoint: Click and drag it
• Set visibility: Right-click a keypoint to toggle between visible, occluded, and not present
• Move entire skeleton: Select all keypoints and drag

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Tips

• Place the most visible keypoints first, then fill in occluded ones
• Mark keypoints as “not present” rather than guessing their location if they are fully hidden
• Use zoom for precise placement on small or distant subjects
• Keypoints can be tracked across video frames for pose tracking

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Common Controls

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Selection

• Press V to switch to the Select tool
• Click an annotation to select it
• Click empty canvas to deselect
• Hold Ctrl / ⌘ and click to multi-select

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Move and Resize

• Drag a selected annotation to reposition it
• Drag handles to resize
• Use the properties panel for exact numeric values

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Delete

• Select one or more annotations
• Press Delete or Backspace
• Confirm deletion if prompted

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Undo / Redo

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Save

• Press Ctrl+S / ⌘S to save your work
• The viewer auto-saves periodically, but manual saves are recommended before navigating away

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Zoom and Pan

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Tool Shortcuts Reference

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General Tips

• Switch tools quickly: Use single-key shortcuts to switch between tools without reaching for the toolbar
• Zoom in for precision: Small objects and fine boundaries benefit from zooming in before drawing
• Use undo liberally: It is faster to undo a mistake than to manually correct it
• Review at full zoom-out: After annotating, zoom out to verify nothing was missed
• Keyboard over mouse: Almost every action has a keyboard shortcut; learning them significantly speeds up annotation

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Next Steps

• Follow the Video Annotation tutorial for tracking workflows
• Learn about AI-Assisted Annotation for SAM and auto-labeling
• See Annotation Types for the data format of each annotation type
• Review Keyboard Shortcuts for the complete shortcut list