Calibration strategy - 18 May 2026

Make every thermal alert auditable

This page specifies a field-reference workflow for turning raw thermal frames into calibration-flagged evidence rather than untraceable operator imagery. It is a written procedure awaiting hardware; no bench or field calibration has been performed yet.

Read the field cadence Read detection pipeline Read radiometry requirements Read survey model Read validation plan Read field-test plan Read detector path

Field kit

The payload needs reference targets, not just a factory-calibrated camera.

Warm A high-emissivity 45-60 deg C target anchors weak hot-spot checks without using live flame.

Ambient A matte reference near scene temperature catches offset drift around the operating background.

Window Pre- and post-flight window checks keep dust, smoke, moisture, and cleaning events out of the calibration blind spot.

Weather Air temperature, humidity, wind, solar condition, payload temperature, and detector warm-up time travel with the flight record.

What changed

Calibration is part of the field workflow and validation boundary.

The strategy uses two reference anchors, detector warm-up, shutter/NUC logging, window-state checks, and repeated reference passes when the route allows them.

Frames can be benchmark-grade, advisory-grade, or uncalibrated. That status follows every alert and dataset export so later validation cannot hide stale calibration.

Flight cadence

Reference checks bracket the survey and repeat when drift risk increases.

Stage	Minimum action	Why it matters
Bench characterization	Record warm-up, NUC/shutter behavior, two-reference response, and window-in/window-out offset.	Prevents the first field flight from discovering detector behavior after the data is needed.
Pre-flight stabilization	Use a 20 minute detector warm-up as the conservative starting rule unless bench data supports less.	Microbolometer drift is an operating condition, not a bookkeeping detail.
Launch reference pass	Capture raw or radiometric frames of warm and ambient targets before survey frames are scored.	Creates the first calibration segment for the flight manifest.
In-flight repeat	Add short reference waypoint passes when route geometry, elapsed time, or payload temperature change justifies them.	Repeated references make drift correction defensible instead of guessed.
Survey frames	Attach calibration version, reference age, detector settings, NUC state, window state, and payload temperature.	Every alert remains replayable against the thermal source data.
Post-flight closeout	Repeat reference frames, inspect the window, and mark the flight benchmark, advisory, or uncalibrated.	Validation metrics cannot be reported before the calibration state is known.

Quality gates

The first calibration gates are provisional but enforceable.

Benchmark-grade

Reference residual within 2 deg C after correction, with stable NUC state and known window condition.

Advisory-grade

Reference residual within 5 deg C, or only pre/post-flight references available. Useful for review, not headline metrics.

Uncalibrated

Missing reference frames, stale correction, unknown shutter/NUC state, or contaminated window state.

Still open

The final absolute radiometry budget remains part of detector, target-signal, and atmosphere closure.

Metadata contract

Calibration state has to travel with raw frames, alerts, and dataset exports.

Each flight manifest should record detector branch and serial, optics profile, window/filter state, firmware and software versions, weather source, route, operator, and storage root.

Each reference record should preserve target ID, target type, emissivity assumption, measured temperature, frame IDs, GPS position, capture time, and validity flag.

Each alert packet should include calibrated and raw values, threshold provenance, calibration version, reference age, detector settings, and a validation-exclusion flag when the frame is only advisory-grade or uncalibrated.