Calculate Grid Convergence Angle (Cartography)


Calculates the rotation angle for true north based on the center point of each feature in a feature class and populates this value in a specified field. This field can be used in conjunction with Data Driven Pages to rotate each map to true north.



CalculateGridConvergenceAngle_cartography (in_features, angle_field, {rotation_method}, {coordinate_sys_field})
ParameterExplanationData Type

Input feature class (points, multipoints, lines, and polygons).

Feature Layer

Existing field that will be populated with the true north calculation value in decimal degrees.


Method in which the rotation value is calculated. Geographic is the default value.

  • GEOGRAPHICAngle is calculated clockwise with 0 at top. This is the default.
  • ARITHMETICAngle is calculated counterclockwise with 0 at right.
  • GRAPHICAngle is calculated counterclockwise with 0 at top.

Field containing a projection engine string for a projected coordinate system to be used for angle calculation. The angle calculation for each feature will be based on the projected coordinate system projection engine string for the specific feature. In cases where there is an invalid value the tool will use the Cartographic coordinate system specified in the Cartography environment settings. The default is none, or no field specified. When no field is specified, the projected coordinate system used for calculation will be taken from the Cartography environment settings.


Code Sample

CalculateGridConvergenceAngle tool example 1 (Python window)

Calculates a true north rotation angle for a feature.

import arcpy
from arcpy import env
arcpy.env.workspace = "C:\data\ProjectData.gdb"
arcpy.CalculateGridConvergenceAngle_cartography ("US_states", "angle", "GEOGRAPHIC", "UTM")
CalculateGridConvergenceAngle tool example 2 (stand-alone Python script)

Calculates a true north rotation angle for point features.

# Name:
# Description: Calculates the true north rotation angle for features
# Author: ESRI

# Import system modules
import arcpy
from arcpy import env

# Set environment settings
arcpy.env.workspace = "C:\Data\ProjectData.gdb"

# Set local variables
inFeatures = "US_states"
angleField = "angle"
rotationMethod = "GEOGRAPHIC"
coordSystemField = "UTM"

# Execute CalculateGridConvergenceAngle
arcpy.CalculateGridConvergenceAngle_cartography(inFeatures, angleField,


Cartographic Coordinate System

This setting is used when no coordinate system field is chosen, or if a coordinate system field is chosen and the coordinate system string value is invalid, in which case the coordinate system specified here will be used in the angle calculation.

Related Topics

Licensing Information

ArcView: Yes
ArcEditor: Yes
ArcInfo: Yes