This tab allows you to adjust a number of general settings related to workspaces, the geodetic datasource and basic conversions.
The Default
Horizontal Coordinate Reference System is used as the default for
any Horizontal Coordinate Reference System field that is unpopulated.
The Default Vertical Coordinate Reference System is used as the default for any Horizontal Vertical Reference System field that is unpopulated.
Options
Checking the Always overwrite the output point name for conversions option will overwrite the point name on your output point for Interactive conversions.
Checking the Use the Text Scheme Wizard to define new Text Schemes option will automatically open the Text Scheme Wizard when you select Options > Text File Schemes. When unchecked, the Text File Scheme option will open the Text Scheme Edit form.
Checking the Generate Log File option will generate a log file of your conversions in your system folder, named Calculator.log.
Checking the Enable time-dependent (epoch-based) transformations option will turn on the Time-Dependent Transformations functionality.
Checking the Reverse latitude and longitude option will change the display order for latitude and longitude in the Interactive Conversion job and the Point Database Conversion job.
Checking the Reverse northing and easting option will change the display order for northing and easting in the Interactive Conversion job and the Point Database Conversion job.
Checking Export WKT2 objects in simplified format will change the WKT2 object export format to the simplified version.
Checking Show start page on launch will open the informational Start Page each time the program is launched.
Checking Show Geodetic Base Coordinateswill turn on additional output fields for base geodetic coordinates (when the target coordinate system is Projected) in Interactive Conversion and Point Database Conversion jobs.
Checking Reopen selection dialog to current folder will reopen the recently chosen folder (i.e. Geodetic>Africa) when choosing another coordinate system.
Magnetic Declination
The Display Magnetic Declination will add a field with the magnetic declination value, or the angle between magnetic north and true north, to all Point Database Conversion and Interactive Conversion jobs. Use the drop down menu below to select the Magnetic Declination Model. Available models include: IGRF11, IGRF12, IGRF13, IGRF14, WMM2010, WMM2015, WMM2020, WMM2025, and GUFM1. By default, the latest generation of the IGRF model will be used as it has the greatest valid date range.
GUFM1
This model covers the time period from 1590 to 1990, but is typically not used for dates more recent than 1900.
Four centuries of geomagnetic secular variation from historical records. Jackson, A., Jonkers, A. R. T. and Walker, M. R. Phil. Trans. Roy. Soc. A (2000) Vol. 358, pp957-990.
International Geomagnetic Reference Field (IGRF)
The IGRF magnetic model is a set of spherical harmonic coefficient values developed from observations recorded by satellites, ground observatories, and magnetic surveys. The model can be used to calculate magnetic declination (or variation), the angle between magnetic north and true north at any given point on the ellipsoidal surface. Updates to the IGRF model are released every 5 years, with each iteration in the model updating coefficient data tables to improve the accuracy of calculations, including for past epochs. All IGRF models are referenced to the epoch beginning on 1/1/1900.
IGRF11 - valid date range: 1/1/1900 - 1/1/2015
IGRF12 - valid date range: 1/1/1900 - 1/1/2020
IGRF13 - valid date range: 1/1/1900 - 1/1/2025
IGRF14 - valid date range: 1/1/1900 - 1/1/2030
For more information, see IAGA V-MOD Geomagnetic Field Modeling: International Geomagnetic Reference Field IGRF-13 and
International Geomagnetic Reference Field: the thirteenth generation.
World Magnetic Model (WMM)
The WMM also utilizes spherical harmonic (Gauss) coefficients to deliver calculations of magnetic variation. An updated version of the model is released every five years to address changes in Earth’s magnetic field. Each model is valid for five years from the "Model Epoch" parameter provided in the coefficients table.
WMM2010 - valid date range: 1/1/2010 - 1/1/2015
WMM2015 - valid date range: 10/2/2014 - 1/1/2020
WMM2020 - valid date range: 10/2/2019 - 1/1/2025
WMM2025 - valid date range: 1/1/2025 - 1/1/2030
For more information, see World Magnetic Model (WMM) and The US/UK World Magnetic Model for 2020-2025 : Technical Report
Limit the available coordinate systems by geographic area
Choosing Always will open a window before each coordinate system selection that allows you to limit the coordinate systems by a point or area of your choice.
Choosing Never will take you to the Select Coordinate System from Datasource window with all available coordinate systems available (unless otherwise filtered)
Choosing Ask will prompt you before each coordinate system selection if you would like to limit the coordinate systems by area, or if you would like to select from all available coordinate systems.
Customize Unit Display Settings
Clicking the Customize Unit Display Settings... button will open the Unit Display Settings window, which allows you to set the format of your coordinate data for all windows of the Geographic Calculator.