Summary
Generates a SpatialReference object with a custom projected coordinate system optimal for the specified extent and intended purpose of your map or analysis.
Since there is no way to project a curved surface onto a flat surface without distortion, various map projections exist that compromise between preserving angle, area, distance, or direction. The intended purpose and extent of a map can help determine which of these properties to preserve. For example, a conformal projection may be chosen for a navigational map to preserve bearing, or a projection preserving area may be required to visualize or measure the relative size of features.
Syntax
GenerateOptimalCoordinateSystem (extent, property, {custom_name})
Parameter | Explanation | Data Type |
extent | The extent of interest. The Extent object must have a spatial reference in a geographic coordinate system such as WGS84. | Extent |
property | A property that represents the purpose of the projection.
Not all properties are supported for all extents of interest. The CONFORMAL and EQUIDISTANT_MERIDIANS properties are only supported for large-scale extents, and the COMPROMISE_WORLD property is only supported for full-world extents. The EQUAL_AREA and EQUIDISTANT_ONE_POINT properties are supported for all extents | String |
custom_name | The name of the custom projected coordinate system. If unspecified, the name will be Custom_Projection. | String |
Data Type | Explanation |
SpatialReference | A SpatialReference object with the custom projected coordinate system that is optimal for the specified extent and intended purpose. |
Code sample
Create a custom projected coordinate system that optimizes preserving area over a feature class's extent, and project the feature class to the custom projected coordinate system.
import arcpy
# Input features in Projected Coordinate System
infc = r"C:\Projected.gdb\Colorado_Counties"
# Get extent of features
desc = arcpy.Describe(infc)
extent = desc.extent
# Project the extent to Geographic Coordinate System WGS84
gcs_sr = arcpy.SpatialReference(4326)
prj_extent = extent.projectAs(gcs_sr)
# Create custom projected coordinate system
custom_sr = arcpy.GenerateOptimalCoordinateSystem(prj_extent, "EQUAL_AREA",
"EQUAL_AREA_COLORADO")
# Project the input features to the custom projection
fc_prj = arcpy.management.Project(infc, "TestPoly_Projected", custom_sr)
Create a simple polygon object and project it to a custom projected coordinate system with the conformal property.
import arcpy
gcs_sr = arcpy.SpatialReference(4326) # Create WGS84 spatial reference
# Create polygon
poly_info = [[20, 20], [20, 60], [60, 60], [60, 20], [20, 20]]
poly_pts = arcpy.Array([arcpy.Point(*coords) for coords in poly_info])
poly = arcpy.Polygon(poly_pts, gcs_sr)
# Create extent object from polygon
extent = poly.extent
# Create custom projected coordinate system
custom_sr = arcpy.GenerateOptimalCoordinateSystem(extent, "CONFORMAL")
# Project the polygon to the custom projection
poly_prj = poly.projectAs(custom_sr)