Recording a session

End-to-end walkthrough for capturing an AR session in Stera and locating the resulting .mcap on the iPhone. For getting the file onto a Mac, see Transferring files locally.

Quick start

Open Stera → tap Record → move slowly around the scene → tap Stop.

Wait until the "Saving" / "Processing" indicator disappears.

Open Files → Browse → On My iPhone → Stera → ar_sessions → newest session_YYYYMMDD_HHmmss/.

The MCAP file inside is session_data_YYYYMMDD_HHmmss.mcap.

What gets recorded

When you stop a recording, Stera creates a session folder named with the recording's start time:

session_data_20260506_142233.mcap

metadata.json

thumbnail.jpg

YYYYMMDD_HHmmss is the session start time, so the newest session has the largest number.
The single most important file is the .mcap — it contains camera frames, IMU samples, poses, and other spatial data in one binary.
For full reproducibility (and so the file opens cleanly in tools like Foxglove Studio), keep the entire session folder together.

What's captured

Each session records synchronized streams against a shared clock:

RGB — what the camera sees, at the device's native fps.
LiDAR depth — per-frame depth maps (Pro models only).
6-DOF camera pose — where the phone is in space, frame-by-frame.
IMU — accelerometer and gyroscope at high rate.

Settings

The settings panel lets you tune how Stera captures a session. Open it from the gear icon on the home screen before you start recording — most options are locked while a recording is in progress.

Capture

Frame rate (fps) — pick the RGB capture rate. Higher fps gives smoother motion but produces larger files and drains the battery faster. Lower fps is fine for slow, deliberate tasks.
Resolution — RGB frame size. Drop this if storage is tight or you're capturing long sessions.
LiDAR depth — toggle per-frame depth recording (Pro models only). Off if you don't need depth and want smaller files.
IMU rate — accelerometer/gyroscope sample rate. Leave at default unless a downstream tool requires a specific rate.

Modality	Options	Default
RGB	15 / 30 / 60 Hz	15 Hz
Video resolution	720p / 1080p	720p
LiDAR depth	15 / 30 / 60 Hz	15 Hz
Pointcloud	15 / 30 / 60 Hz	15 Hz
6-DOF camera pose	15 / 30 / 60 Hz	60 Hz
IMU (accel/gyro)	50 / 100 / 200 Hz	100 Hz

The app plays an audio cue when a recording starts and another when it stops, so you know capture is active without needing to look at the screen. You can enable or disable these cues from the settings panel.

Voice commands

Voice control — toggle hands-free recording. When enabled, Stera listens for a small set of wake phrases:
- "Start Recording" / "Stera, record" — begin a recording.
- "Stop Recording", stop" — end the current recording.

Voice control needs the Microphone permission and runs on-device — no audio leaves the phone. Disable it if you're recording in a noisy environment to avoid accidental stops.

Before you start

Device: an iPhone that supports ARKit (A12 Bionic or newer is safe).
iOS: iOS 16 or later recommended.
Free storage: AR sessions can be multiple GB. Keep at least 2–3× the expected session size free.
Battery: stay above ~30%. A shutdown mid-recording can corrupt the file.

Record a session

Open Stera on your iPhone.

Grant any permission prompts the first time you launch.

Hold the iPhone steady facing the scene you want to capture.

Tap the Record button. You should see a recording indicator (timer or red dot) confirming capture is active.

Move slowly and smoothly:

Walk at a relaxed pace.
Keep the phone roughly upright.
Avoid quick rotations or jerks — fast motion blurs frames and degrades tracking.
Re-look at areas you have already seen; this helps the AR system close loops and stay accurate.

Tap Stop to end the recording.

Wait for processing. Stera writes the MCAP, packages companion data, and renders a thumbnail. Don't force-close Stera or lock the phone aggressively while you see a "Saving" or "Processing" indicator.

Once the session appears in the Stera library with a thumbnail, the files are fully written to disk.

Closing the app early can leave the MCAP truncated. Always wait for the "Processing" indicator to disappear.

Tips for a good recording

Start the recording with the phone already pointed at the scene.
Frame the task, not yourself — keep the subject and your hands in view.
Keep the scene reasonably well-lit. ARKit struggles in dim or textureless environments (blank walls, glossy surfaces).
Aim for sessions of 30 seconds to a few minutes. Very long sessions produce very large files.
One task per session is easier to label and process than long mixed clips.

Troubleshooting

I can't find the Stera folder in Files → On My iPhone. Open Stera and record a short session. The folder is created the first time Stera writes to disk. Force-quit and reopen Files afterward.

Recording stopped on its own. Usually thermal — the iPhone got hot. Let it cool down for a few minutes, then try a shorter session. Less commonly: low battery or low storage.

Transferring files locally — get the MCAP off the iPhone and onto a Mac.