Calculate Magnetic Components (Topographic Production Tools)

Summary

Calculates the magnetic field at point locations for a given date and altitude.

Usage

Caution:

This tool modifies the input data. See Tools that modify or update the input data for more information and strategies to avoid undesired data changes.

The Input Features parameter value must be points. You can filter input points by applying a layer definition query or selection set.
The Altitude parameter specifies the elevation as a linear unit of the input points. The Altitude value must be a numeric value above sea level. Do not use decimal degrees or unknown units.
The Altitude parameter applies the same elevation value to all points in the Input Features parameter value. To use a different altitude value for each input point, use the Iterate Feature Selection or Iterate Field Value tool in ModelBuilder. The iterator can pass a value to the Altitude parameter. In this configuration, the tool runs once per input point.
Magnetic field values are written to existing fields. This tool does not create fields. To add a field, use the Add Field tool.
The Magnetic Component parameter field controls the type of magnetic field calculation. You must specify a magnetic component and an existing field to write to. You can calculate up to nine magnetic component types.
To use the Grid variation option for the Magnetic Component parameter, you must set the ArcGIS Pro data frame coordinate system to Lambert Conformal Conic. If you specify Grid variation with another coordinate system, the tool will fail.
This tool uses the World Magnetic Model 5-year epoch specific to the data provided. For example, if the data specified is from 2020, the model epoch released at the end of 2019 is used.
Use the Magnetic Model file parameter to run the tool with an unconventional model.

Caution:

If the standard World Magnetic Model is not used, the model specified must match the WMM.xml file structure.

Label	Explanation	Data type
Input Features	The point features for which magnetic field values will be calculated.	Feature Layer
Altitude	The elevation of the Input Features value including the linear unit. Do not use decimal degrees or unknown units. The default is 0 meters.	Linear Unit
Date	The date for which magnetic field values will be calculated. The date must be valid for the specified World Magnetic Model. The format must use two digits for the month, two digits for the day, and four digits for the year. The default is the system current date.	Date
Magnetic Component	The magnetic component that will be calculated and the field where the values will be written. Value table columns: Component—The component type that will be used in the magnetic field calculation. Declination—The angle between magnetic north and true north. This value varies by location on the globe. Annual Drift—The annual rate of change in magnetic declination. This value varies by location on the globe. Inclination—The angle between a compass needle and the plane of the horizon. Inclination is also known as magnetic dip or the dip of the compass needle. This value varies by latitude. Horizontal—This value is calculated using north and east components. Horizontal is also known as Horizontal intensity, or H. This value varies by location on the globe. East Component—The easterly intensity of the geomagnetic field. East component is also known as Y. This value varies by location on the globe. North Component—The northerly intensity of the geomagnetic field. North component is also known as X. This value varies by location on the globe. Vertical Intensity—The vertical intensity of the geomagnetic field. Vertical intensity is also known as Z. This value varies by location on the globe. Total Intensity—This value is calculated using horizontal and vertical components. Total intensity is also known as F. This value varies by location on the globe. Grid Variation—The angle between magnetic north and grid north. You must use the Lambert conformal conic projected coordinate system in the map frame, in the geoprocessing environment, or in the input point data. Field—The field where calculated results will be written.	Value Table
Magnetic Model file (Optional)	The `.xml` file that will be used for the magnetic model. Review the `WMM.xml` file in `Resources\Defense` for an example of the expected format.	File

Derived output

Label	Explanation	Data type
Updated Features	The Input Features layer with the chosen fields updated.	Feature Layer

arcpy.topographic.CalculateMagneticComponents(in_features, altitude, date, magnetic_component, {wmm_file})

Name	Explanation	Data type
in_features	The point features for which magnetic field values will be calculated.	Feature Layer
altitude	The elevation of the `in_features` value including the linear unit. Do not use decimal degrees or unknown units. The default is 0 meters.	Linear Unit
date	The date for which magnetic field values will be calculated. The date must be valid for the specified World Magnetic Model. The format must use two digits for the month, two digits for the day, and four digits for the year. The default is the system current date.	Date
magnetic_component [[component, field],...]	The magnetic component that will be calculated and the field where the values will be written. Value table columns: `Component`—The component type that will be used in the magnetic field calculation. `DECLINATION`—The angle between magnetic north and true north. This value varies by location on the globe. `ANNUAL_DRIFT`—The annual rate of change in magnetic declination. This value varies by location on the globe. `INCLINATION`—The angle between a compass needle and the plane of the horizon. Inclination is also known as magnetic dip or the dip of the compass needle. This value varies by latitude. `HORIZONTAL`—This value is calculated using north and east components. Horizontal is also known as Horizontal intensity, or H. This value varies by location on the globe. `EAST_COMPONENT`—The easterly intensity of the geomagnetic field. East component is also known as Y. This value varies by location on the globe. `NORTH_COMPONENT`—The northerly intensity of the geomagnetic field. North component is also known as X. This value varies by location on the globe. `VERTICAL_INTENSITY`—The vertical intensity of the geomagnetic field. Vertical intensity is also known as Z. This value varies by location on the globe. `TOTAL_INTENSITY`—This value is calculated using horizontal and vertical components. Total intensity is also known as F. This value varies by location on the globe. `GRID_VARIATION`—The angle between magnetic north and grid north. You must use the Lambert conformal conic projected coordinate system in the map frame, in the geoprocessing environment, or in the input point data. `Field`—The field where calculated results will be written.	Value Table
wmm_file (Optional)	The `.xml` file that will be used for the magnetic model. Review the `WMM.xml` file in `Resources\Defense` for an example of the expected format.	File

Derived output

Name	Explanation	Data type
updated_features	The `in_features` layer with the chosen fields updated.	Feature Layer

Code sample

CalculateMagneticComponents example 1 (stand-alone script)

The following code sample demonstrates how to use the CalculateMagneticComponents function in Python.

# Name: CalculateMagneticComponents_sample.py
# Description: Calculates four types of magnetic component fields for a feature class.

# Import System Modules
import arcpy

# Setting Data Variables
ElevP2 = r'C:\Data\Edit_Sample.gdb\Features\ElevP'
ElevP_Layer = 'ElevP_Layer'

# Make Feature Layer from the ElevP feature class
arcpy.management.MakeFeatureLayer(ElevP2, ElevP_Layer)

# Add four magnetic component fields
arcpy.management.AddField('ElevP_Layer', 'Declination', 'LONG')
arcpy.management.AddField('ElevP_Layer', 'Annual_Drift', 'LONG')
arcpy.management.AddField('ElevP_Layer', 'Inclination', 'LONG')
arcpy.management.AddField('ElevP_Layer', 'Horizontal', 'LONG')

# Setting Local Variables
altitude = '1 Feet'
date = '1/1/2010'
magnetic_component = 'DECLINATION Declination;ANNUAL_DRIFT Annual_Drift;INCLINATION Inclination;HORIZONTAL Horizontal'

# Run Calculate Magnetic Components
arcpy.topographic.CalculateMagneticComponents('ElevP_Layer', altitude, date, magnetic_component, '')

CalculateMagneticComponents example 2 (stand-alone script)

The following code sample demonstrates how to use the CalculateMagneticComponents function in Python.

# Name: CalculateMagneticComponents_sample.py
# Description: Calculates the declination for a feature class using user provided magnetic model file.

# Import System Modules
import arcpy

# Setting Data Variables
ElevP2 = r'C:\Data\Edit_Sample.gdb\Features\ElevP'
ElevP_Layer = 'ElevP_Layer'
wmm_file = r'C:\Data\Test_WMM.xml'

# Make Feature Layer from the ElevP feature class
arcpy.management.MakeFeatureLayer(ElevP2, ElevP_Layer)

# Add four magnetic component fields
arcpy.management.AddField('ElevP_Layer', 'Declination', 'LONG')

# Setting Local Variables
altitude = '1 Feet'
date = '1/1/2010'
magnetic_component = 'DECLINATION Declination'

# Run Calculate Magnetic Components
arcpy.topographic.CalculateMagneticComponents('ElevP_Layer', altitude, date, magnetic_component, wmm_file)

Environments

Current Workspace

Licensing information

Basic: No
Standard: Requires Topographic Mapping or Aviation Airports or Aviation Charting or Maritime or Bathymetry
Advanced: Requires Topographic Mapping or Aviation Airports or Aviation Charting or Maritime or Bathymetry

Calculate Magnetic Components (Topographic Production Tools)

Summary

Usage

Caution:

Caution:

Parameters

Derived output

Environments

Licensing information

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