Frame Navigation

Efficient frame navigation is essential for fast, accurate annotation. Master Annotator provides multiple ways to move through your trajectory data — from fine-grained single-frame stepping to full-speed playback.

Overview

Every dataset in Master Annotator is a sequence of frames, where each frame corresponds to one row in your CSV file. The navigation controls let you move through this sequence to inspect the robot's behavior at each timestep and apply labels.

All navigation methods are synchronized — the timeline scrubber, 3D viewer, video panel, and joint graphs all update together when you change frames.

Timeline Scrubber

The timeline scrubber is a horizontal bar displayed at the bottom of the labeling interface. It provides a visual overview of the entire trajectory and shows your current position within it.

• Click anywhere on the timeline to jump directly to that frame.
• Click and drag the scrubber handle to smoothly scan through the trajectory. The 3D viewer and video panel update in real-time as you drag.
• Label colors are displayed on the timeline as colored segments, giving you a visual overview of which frames have been labeled and with which labels.

Arrow Key Navigation

The left and right arrow keys provide keyboard-driven frame navigation:

• Right Arrow — Move forward by the current step size.
• Left Arrow — Move backward by the current step size.
• Home — Jump to the first frame (frame 0).
• End — Jump to the last frame.

Arrow key navigation respects the configured step size, so pressing Right Arrow with a step size of 5 advances by 5 frames instead of 1.

Configurable Step Size

The step size determines how many frames you advance or retreat with each navigation action (arrow keys and Auto-Advance mode). Available step sizes:

• 1 — Every frame (default). Maximum precision.
• 5 — Skip 4 frames per step. Good for quick scanning.
• 10 — Skip 9 frames per step. Fast traversal of long trajectories.
• Custom — Set any integer value via the Annotation Settings.

The step size can be changed at any time from the annotation toolbar without interrupting your workflow.

Play / Pause

Press Space to start or stop automatic playback. During playback, the viewer advances through frames at the configured FPS (frames per second), animating the robot and video in real-time.

• Default FPS: 10 frames per second. Adjust in Annotation Settings.
• Shared controls: Play/pause is shared between the 3D viewer and the video panel — both start and stop together.
• Looping: Playback stops automatically when it reaches the last frame.

Jump to Frame

To navigate directly to a specific frame, use the frame input field in the annotation toolbar. Type a frame number and press Enter to jump to that exact position. This is useful when you know the frame number from a previous annotation pass, an external tool, or a team member's notes.

Frame Counter

The frame counter is displayed in the annotation toolbar and shows your current position in the format:

current / total

For example, 142 / 3000 means you are on frame 142 out of 3000 total frames. The counter updates in real-time as you navigate, giving you constant awareness of where you are in the trajectory.

Navigation Reference