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The Changepoint Detection workflow monitors RHEED streams in real time and flags changepoints as a growth unfolds: the moments where the signal’s behavior shifts. Each detected changepoint is matched against reference changepoints you have already labelled elsewhere in the same project, so recurring events inherit consistent, human-meaningful labels. Surfacing these events as they happen lets you respond quickly to unexpected changes in deposition. It runs automatically on RHEED data once a project with labelled reference changepoints is in place. See Setting up reference changepoints.

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Detection Process

For each monitored RHEED stream:
  1. Detect: As the stream arrives, the workflow continuously scans the derived metric timeseries for changepoints.
  2. Score severity: Each changepoint is assigned a severity (High, Moderate, or Low) reflecting how large the shift is.
  3. Label from references: Each new changepoint is compared against the labelled reference changepoints in its project. If a close enough match exists for the same metric, the changepoint inherits that label. Otherwise it stays Unlabelled until someone labels it.

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Setting up reference changepoints

The labels applied to detected changepoints come entirely from changepoints you have already labelled in the same project. A project that has no labelled changepoints still detects events, but those events stay unlabelled. Setting a project up as the label source takes a few steps.
1

Choose or create a project

Pick the project that will hold both the reference data and the sample you want to monitor, or create a new one.
2

Add labelled reference data items

Add one or more data items from earlier runs of this workflow to the project, then label their changepoints. These labelled changepoints define the full set of labels that can be applied during monitoring.
3

Add the sample you want to monitor

Add the physical sample for the new growth to the same project, so its detected changepoints can be matched against the references.
4

Stream the growth

Start streaming. Detected changepoints are matched against the project’s references and labelled automatically as they appear.
If the project has no labelled changepoints for this workflow yet, detected changepoints are still flagged, but they remain unlabelled. Label the matching changepoints on data items already in the project to use them as references.
Only labelled changepoints on the same data modality and metric are considered as references, so a label set on one RHEED metric is never applied to a different metric.

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How changepoints appear

Detected changepoints surface in two places in the Monitor view.As bars on the timeseries chart: In the Growth Metrics panel, each changepoint is drawn as a colored vertical band over the chart at the time it occurred. The color encodes severity: red for High, amber for Moderate, and blue for Low. Instantaneous changepoints are widened to a minimum so they stay visible, and the time axis can be switched between elapsed time and absolute timestamps.In the activity timeline: The Details sidebar’s Activity tab lists every changepoint as a row, ordered through the run, showing its timestamp, the metric it was found on, a severity badge, and its label (or Unlabelled). You can filter the timeline by label, deviation, and assigner, relabel an event, add notes, or request a suggested label. An info card shows which project is supplying the labels and the categories available.

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Severity

Severity reflects how large the detected shift is and drives the color of the changepoint in the chart and timeline:
SeverityColorMeaning
HighRedA large shift. Investigate promptly.
ModerateAmberA noticeable shift that may be worth review.
LowBlueA subtle or minor shift.
Default thresholds apply across your organization. Per-project and per-data-item overrides let you tighten thresholds for sensitive metrics or relax them for known-noisy signals.