Running your first measurement

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With the SDK installed and initialized, you're ready to perform your first measurement.

This article explains what happens during a measurement, what your application needs before a scan can begin, and how to determine whether the measurement completed successfully or needs to be repeated.

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Before you start a measurement

Before triggering a scan, make sure your application is ready to begin the measurement process.

At a minimum, this means:

- the SDK has been successfully initialized,
- your application has permission to access the camera,
- the device meets the minimum system requirements,
- the camera preview is visible to the user.

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Depending on your platform, there may be additional implementation steps. Refer to the platform-specific documentation for installation and initialization details.

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Starting a measurement

Once your application is ready, you can start a measurement using the SDK.

From the user's perspective, the process is simple: they position their face within the camera preview and remain relatively still while the SDK analyzes the video stream. You can see use instructions for optimal performance here.

Behind the scenes, Shen AI continuously evaluates the quality of the captured signal. The SDK automatically determines when enough high-quality data has been collected to calculate the requested measurements.

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What happens during the scan?

While the measurement is running, the SDK guides the user through the process.

Depending on your integration, users may receive feedback about:

- whether their face is correctly positioned,
- whether lighting conditions are sufficient,
- whether they're moving too much,
- whether the signal quality is good enough to continue.

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Providing this real-time feedback helps users complete successful measurements on their first attempt.

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Detecting when a measurement is complete

A standard Shen AI measurement takes 30 seconds. In most cases, the SDK collects enough physiological data within this time to assess the requested measurements and automatically completes the scan.

Occasionally, the measurement may take a little longer. This typically happens when the SDK needs additional data because the signal quality isn't sufficient. Common reasons include:

- excessive user movement,
- poor lighting conditions,
- the user's face not being fully visible,
- temporary drops in signal quality.

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Rather than stopping after a fixed amount of time, Shen AI continuously evaluates the quality of the captured signal throughout the measurement. If additional high-quality data is needed, the scan continues until enough information has been collected or the measurement can no longer be completed successfully.

When the measurement is complete, the SDK automatically returns the results to your application. At this point, your application can display the measurements, save them, or use them as part of your own workflows.

If the SDK cannot collect enough reliable data, it reports the reason the measurement failed. Your application can then guide the user through another attempt, for example, by asking them to improve the lighting, reposition themselves, or remain still during the scan.

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Why a measurement might not start

If a measurement doesn't begin, the cause is usually one of a few common issues.

The SDK hasn't been initialized successfully. Before starting a measurement, verify that initialization completed without errors and that you're using a valid SDK key.

The application doesn't have permission to access the camera. Make sure camera permissions have been requested and granted before attempting to start a scan.

The device doesn't meet the minimum system requirements. Unsupported operating systems, browsers, or hardware may prevent the SDK from running correctly.

The camera isn't available. This can happen if another application is already using the camera or if the device doesn't provide access to a supported camera.

If everything appears to be configured correctly but measurements still don't start, consult the platform-specific troubleshooting guides in the Developer Portal.