[j-w9]

"Use position throughout flight rather than just using a single origin" from #81. Built on #373 (its commit is included), so that should go first.

When the log has POS, the earth field is evaluated along the track (at most one point per second, skipping 0,0 before a fix) and interpolated to each attitude/compass sample time for the body frame expected field. A "Use position along flight" checkbox in the Location box controls this. It is ticked by default when there is a track and disabled when there is none. The single Location is still used for intensity and declination in the plots, and when the box is unticked.

With the WMM the field changes by roughly 1 mGauss per 10 km and 7 to 10 mGauss per 100 km (1.4 to 1.7%) at the locations I checked, so this mainly matters for long range flights. On two short logs, fitted offsets move by about 0.005 mGauss. With the box unticked, results are identical to #373, and the interpolated field matches direct evaluation at the track points.

[AP-Review]

Deprecated — see below for the updated review.

Previous review (2026-11-09)

Automated review note — AI-generated (Claude+Codex), validated against the live diff. Please sanity-check before acting.
Verdict: COMMENT

Reviewed at head c343ceac47.
Full report: https://firmware.ardupilot.org/Tools/APReview/DevCallReviews/PRReviews/ardupilot/webtools/374/1.html#prWebTools-374

WMM2025 model, altitude/date inputs and track interpolation check out (coefficients match NOAA, field values match pygeomag); two nonblocking items remain.

Should fix

• MAGFit/magfit.js:818 With "Use position along flight" ticked, get_yaw still uses the single-location earth_field.declination (magfit.js:894) and the field-length reference is a flat earth_field.intensity line (magfit.js:416). On long routes a correct compass shows a fake yaw drift, about 8° over 60N 110W to 100W. Derive the declination per sample from atan2(y, x) of the interpolated track vector, and plot the track vector's magnitude over time.

Minor

• MAGFit/magfit.js:1762 get_log_date returns undefined for pre-instance GPS logs, so they get today's date. log.extractStartTime() || new Date() already handles both formats, and AirspeedFit/LogFinder use it.

[AP-Review]

Automated review note — AI-generated (Claude+Codex), validated against the live diff. Please sanity-check before acting.
Verdict: COMMENT

Reviewed at head 24b5876371.
Full report: https://firmware.ardupilot.org/Tools/APReview/DevCallReviews/PRReviews/ardupilot/webtools/374/2.html#prWebTools-374

The WMM2025 model still matches the published coefficients (all 90 coefficients identical, and field values agree with pygeomag), but both items from the last review are still open.

Since then, only the Location tooltip changed (the 2025-2030 validity note); there was no code change and no reply.

Should fix

• MAGFit/magfit.js:818 Track yaw diagnostics (still open): with "Use position along flight" on, get_yaw still uses the single earth_field.declination (magfit.js:894) and the field-length reference is flat (magfit.js:416), so a perfect compass shows about 8° of false yaw drift between 110W and 100W at 60N. Take the declination per sample from atan2(y, x) of the interpolated track vector, and plot the track magnitude.

Minor (1)

• MAGFit/magfit.js:1762 Log date (still open, narrower than first stated): get_log_date ignores non-instanced GPS. Because load already rejects non-instanced MAG, this only affects logs from dev builds between 2 and 19 November 2020 (instanced MAG, plain GPS), which get today's date. log.extractStartTime() || new Date() handles both layouts.

Not fully reviewed: no end-to-end browser run with real logs, so on-page rendering and long-log performance are untested.