GeoMagSharpGUI

A C# WinForms application for calculating geomagnetic field values using spherical harmonic models. This is a port of the NOAA Geomag 7.0 software with a modern graphical interface.

Overview

GeoMagSharpGUI calculates Earth's magnetic field components (declination, inclination, intensity) at any location and date using coefficient files from models like:

• IGRF (International Geomagnetic Reference Field)
• WMM (World Magnetic Model)
• DGRF (Definitive Geomagnetic Reference Field)
• EMM (Enhanced Magnetic Model)

Features

• Calculate magnetic declination, inclination, and field intensity
• Support for multiple coordinate input formats (Decimal Degrees, DMS)
• GPS location integration via Windows Location Services
• Historical calculations with date range support
• Multiple output units (nanoTesla, Gauss)
• Secular variation (change per year) calculations
• Save results to file
• User-configurable preferences

Solution Structure

GeoMagGUI.sln
├── GeoMagGUI/              # WinForms Application (.NET Framework 4.0)
│   ├── coefficient/        # Magnetic model coefficient files
│   │   ├── IGRF12.COF
│   │   ├── WMM2015.COF
│   │   └── MagneticModels.json
│   ├── assets/             # Icons and images
│   ├── documentation/      # License and docs
│   ├── frmMain.cs          # Main application window
│   ├── frmAddModel.cs      # Add model dialog
│   ├── frmPreferences.cs   # User preferences dialog
│   └── Program.cs          # Application entry point
│
├── GeoMagSharp/            # Core Calculation Library (.NET Framework 4.0)
│   ├── GeoMag.cs           # Main calculation orchestrator
│   ├── Calculator.cs       # Spherical harmonic calculations
│   ├── DataModel.cs        # Data structures and models
│   ├── ModelReader.cs      # Coefficient file parser
│   ├── Units.cs            # Unit conversion utilities
│   └── GeoMagException.cs  # Custom exception types
│
├── GeoMagSharp-UnitTests/  # Unit Tests (MSTest, .NET Framework 4.5.2)
│   └── ExtensionMethodsUnitTest.cs
│
└── docs/                   # Documentation
    ├── prompts/            # Claude personas and prompt templates
    └── features/           # Feature specifications and plans

Build Requirements

• Visual Studio 2019 or later
• .NET Framework 4.0 (GUI and Library)
• .NET Framework 4.5.2 (Unit Tests)

Build Commands

Use Developer Command Prompt for Visual Studio:

# Debug build (x86)
msbuild GeoMagGUI.sln /p:Configuration=Debug /p:Platform="x86"

# Release build (x86)
msbuild GeoMagGUI.sln /p:Configuration=Release /p:Platform="x86"

# Run unit tests
vstest.console.exe GeoMagSharp-UnitTests\bin\Debug\GeoMagSharp-UnitTests.dll

Usage

1. Select a Magnetic Model - Choose from available models (IGRF, WMM, etc.)
2. Enter Location - Input coordinates as decimal degrees or DMS
3. Set Elevation - Enter altitude above MSL or depth below MSL
4. Choose Date(s) - Select single date or date range
5. Calculate - View magnetic field results in the grid
6. Save Results - Export to text file if needed

Magnetic Field Components

Component	Description
Declination	Angle between true north and magnetic north
Inclination	Angle between horizontal and magnetic field vector
Horizontal Intensity	Horizontal component of magnetic field
North Component	Northward component of horizontal intensity
East Component	Eastward component of horizontal intensity
Vertical Component	Vertical component of magnetic field
Total Field	Total magnetic field intensity

Adding New Models

1. Obtain coefficient file (.COF or .DAT format)
2. Place in GeoMagGUI/coefficient/ directory
3. Use Tools > Add Model to register the model
4. Model will be available in the dropdown

Dependencies

• Newtonsoft.Json v10.0.1 - JSON serialization
• System.Device - GPS location services (Windows)

Architecture

┌─────────────────────────────────────┐
│   Presentation (WinForms)           │
│   frmMain, dialogs, UI controls     │
├─────────────────────────────────────┤
│   Business Logic (GeoMagSharp)      │
│   GeoMag, Calculator, Models        │
├─────────────────────────────────────┤
│   Data Access                       │
│   ModelReader, JSON serialization   │
├─────────────────────────────────────┤
│   External Data                     │
│   COF/DAT coefficient files         │
└─────────────────────────────────────┘

Contributing

See AGENTS.md for coding standards and development guidelines.

For Claude Code assistance, see docs/prompts/ for personas and templates.

License

See GeoMagGUI/documentation/LICENSE

Credits

• Original NOAA Geomag 7.0 software
• British Geological Survey (BGS) calculation algorithms
• Port to C# with GUI by StreckerCM