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Annotations

Relay provides a full annotation system for marking up your data with shapes, text, segmentation masks, and comments.

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Annotation types

All annotations are stored in world coordinates, ensuring they stay aligned with the image regardless of zoom or pan.

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Annotation scoping

Annotations can be scoped to:
  • Per Z-slice — visible only on a specific Z-plane
  • Per time-point — visible only at a specific time
  • All slices — visible across the entire Z-stack

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Annotation features

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Styling

  • Fill color, stroke color, stroke width, and opacity
  • Per-annotation style customization

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Organization

  • Z-order management — bring to front, send to back, move up/down
  • Per-pane visibility — the same annotation can be shown or hidden independently per pane
  • Copy across documents — copy annotations between different files

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Segmentation metadata

Annotations from model outputs (like SAM3) include:
  • Instance ID
  • Class label
  • Confidence score
  • Model name that generated the annotation

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Document model

Annotations are organized into documents (collections):
  • Documents can be scoped to a tab or pane
  • Multiple documents per pane, switchable
  • Persisted locally in IndexedDB

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Comments

Relay supports threaded comments attached to specific locations in your images:
  • Position-linked — comments are tied to a specific view state and location
  • Threaded replies — reply to comments to create discussions
  • Resolve/unresolve — mark comments as resolved when addressed
  • Per-pane modals — comment panels are independent per pane
  • Server persistence — comments sync to the server for shared workspaces
  • Read-only in shares — viewers can read but not add comments on shared links

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Keypoint labeling

Relay includes a dedicated keypoint annotation workflow designed for creating DeepLabCut training datasets:
  • Session-based — create labeling sessions with defined keypoint schemas
  • Frame navigation — step through video frames or image stacks
  • Individual keypoint selection — click to place each keypoint
  • Undo/redo — full history stack for corrections
  • Color palettes — customizable keypoint colors
  • Export — export labeled keypoints for model training