Spline (Spatial Analyst)

Summary

Interpolates a raster surface from points using a two-dimensional minimum curvature spline technique.

The resulting smooth surface passes exactly through the input points.

Learn more about how Spline works

Usage

Syntax

Spline (in_point_features, z_field, {cell_size}, {spline_type}, {weight}, {number_points})
ParameterExplanationData Type
in_point_features

The input point features containing the z-values to be interpolated into a surface raster.

Feature Layer
z_field

The field that holds a height or magnitude value for each point.

This can be a numeric field or the Shape field if the input point features contain z-values.

Field
cell_size
(Optional)

The cell size at which the output raster will be created.

This will be the value in the environment if it is explicitly set; otherwise, it is the shorter of the width or the height of the extent of the input point features, in the input spatial reference, divided by 250.

Analysis Cell Size
spline_type
(Optional)

The type of spline to be used.

  • REGULARIZED Yields a smooth surface and smooth first derivatives.
  • TENSION Tunes the stiffness of the interpolant according to the character of the modeled phenomenon.
String
weight
(Optional)

Parameter influencing the character of the surface interpolation.

When the REGULARIZED option is used, it defines the weight of the third derivatives of the surface in the curvature minimization expression. If the TENSION option is used, it defines the weight of tension.

The default weight is 0.1.

Double
number_points
(Optional)

The number of points per region used for local approximation.

The default is 12.

Long

Return Value

NameExplanationData Type
out_raster

The output interpolated surface raster.

Raster

Code Sample

Spline example 1 (Python window)

This example inputs a point shapefile and interpolates the output surface as a TIFF raster.

import arcpy
from arcpy import env  
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outSpline = Spline("ozone_pts.shp", "ozone", 2000, "REGULARIZED", 0.1)
outSpline.save("C:/sapyexamples/output/splineout.tif")
Spline example 2 (stand-alone script)

This example inputs a point shapefile and interpolates the output surface as a GRID raster.

# Name: Spline_Ex_02.py
# Description: Interpolate a series of point features onto a 
#    rectangular raster using a minimum curvature spline technique.
# Requirements: Spatial Analyst Extension
# Author: ESRI

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inPntFeat = "ozone_pts.shp"
zField = "ozone"
cellSize = 2000.0
splineType = "REGULARIZED"
weight = 0.1

# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")

# Execute Spline
outSpline = Spline(inPntFeat, zField, cellSize, splineType, weight)

# Save the output 
outSpline.save("C:/sapyexamples/output/splineout02")

Environments

Related Topics

Licensing Information

ArcView: Requires Spatial Analyst or 3D Analyst
ArcEditor: Requires Spatial Analyst or 3D Analyst
ArcInfo: Requires Spatial Analyst or 3D Analyst

6/29/2011