[general]
name=Meridian
qgisMinimumVersion=3.22
qgisMaximumVersion=4.99
description=Provides magnetic declination, grid convergence and grid magnetic angle for any location and date (1900–2030) — fully offline, using WMM, WMMHR and IGRF-14 models.
version=0.2.1
author=Steve Graham
email=stevengraham84@gmail.com
about=As geologists we deal with azimuths a lot — compass readings, drill collar orientations, structural logging, downhole surveys. The reference for an azimuth is critical: is it relative to magnetic north, true north, or the grid system you're working in? When starting a new project, one of the first tasks is to orient yourself and work out the differences between these references and how to convert between them.

    If they were static it would be easy — but the magnetic field changes over time, and there are models that predict its effect across the globe and across the years. Sometimes you don't just need today's difference, but what it was when a hole was drilled, so you can verify the correct adjustment was made.

    Meridian aims to make this job a little easier. Give it a lat/long, or pick a point off the map, and it returns the adjustments you need for the specified date. It will even drop all of the info into an image or PDF for your project documentation. And if you need to process an entire dataset, feed it a point or polygon layer and it will calculate the adjustments using a date field in your data — or a date you specify.

    Disclaimer: Values are derived from global geomagnetic models (WMM/WMMHR/IGRF-14) and are approximations only. Local magnetic anomalies and model limitations mean results may differ from observed values. Always cross-check critical figures against a trusted independent source before use in survey or safety-critical applications.

tracker=https://github.com/stevengraham/meridian/issues
repository=https://github.com/stevengraham/meridian
homepage=https://github.com/stevengraham/meridian

tags=magnetic declination,grid convergence,north correction,WMM,IGRF,survey,geophysics,compass,azimuth,bearing

category=Vector
icon=icon.png

experimental=False
deprecated=False
server=False
hasProcessingProvider=no

changelog=
    0.2.1 — Fix flake8 style warnings (unused imports, semicolons, ambiguous names).

    0.2.0 — Add IGRF-14 support for historical magnetic declination (1900–2030).

    0.1.0 — Initial release.
        Bundled WMM2010, WMM2015v2, WMM2020, WMMHR2025 coefficient files.
        Auto, All, and Specific model modes.
        Per-feature date field parsing (11 formats including DD/MM/YYYY).
        Grid convergence computed numerically from layer CRS.
        Background QgsTask for WMMHR2025 datasets.
        Full component output (I, H, F, X, Y, Z).
        PDF/PNG north-arrow report with worked examples.
        Map-click tool for manual point entry.
        IGRF-14 model bundled for historical dates (1900–2010).
