ATan (Image Analyst)

Available with Spatial Analyst license.

Available with Image Analyst license.

Summary

Calculates the inverse tangent of cells in a raster.

Illustration

ATan illustration
OutRas = ATan(InRas)

Usage

  • In mathematics, all trigonometric functions have a defined range of valid input values called the domain. The output values from each function also has a defined range. For this tool the following are true:

    • The Domain is: -∞ < [in_value] < ∞

    • The Range is: -pi/2 ≤ [out_value] ≤ pi/2

    Note that -∞ and ∞ represent the smallest negative and largest positive value supported by the particular raster format, respectively.

  • The input values to this tool are interpreted as unitless.

  • Output values are always floating point, regardless of the input data type.

  • The output values from this tool are in radians. To use degrees instead, the resulting raster must be multiplied by the radians-to-degrees conversion factor of 180/pi, or approximately 57.296.

    For further assistance, a procedure to follow and examples of converting output in radians to degrees are available.

  • If the input is a multiband raster, the output will be a multiband raster. The tool will perform the operation on each band in the input.

  • In ArcPy, if the input is a multidimensional raster, all slices from all variables will be processed, and the output will be a multidimensional raster.

Parameters

LabelExplanationData Type
Input raster or constant value

The input for which to calculate the inverse tangent values.

To use a number as an input for this parameter, the cell size and extent must first be set in the environment.

Raster Layer; Constant

Return Value

LabelExplanationData Type
Output raster

The output raster.

The values are the inverse tangent of the input values.

Raster

ATan(in_raster_or_constant)
NameExplanationData Type
in_raster_or_constant

The input for which to calculate the inverse tangent values.

To use a number as an input for this parameter, the cell size and extent must first be set in the environment.

Raster Layer; Constant

Return Value

NameExplanationData Type
out_raster

The output raster.

The values are the inverse tangent of the input values.

Raster

Code sample

ATan example 1 (Python window)

This example calculates the inverse tangent of the values in the input Grid raster.

import arcpy
from arcpy import env
from arcpy.ia import *
env.workspace = "C:/iapyexamples/data"
outATan = ATan("degs")
outATan.save("C:/iapyexamples/output/outatan")
ATan example 2 (stand-alone script)

This example calculates the inverse tangent of the values in the input Grid raster and outputs a TIFF raster.

# Name: ATan_Ex_02.py
# Description: Calculates the inverse tangent of pixels in a raster
# Requirements: Image Analyst Extension

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

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

# Set local variables
inRaster = "degs"

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

# Execute ATan
outATan = ATan(inRaster)

# Save the output 
outATan.save("C:/iapyexamples/output/outatan.tif")

Licensing information

  • Basic: Requires Image Analyst or Spatial Analyst
  • Standard: Requires Image Analyst or Spatial Analyst
  • Advanced: Requires Image Analyst or Spatial Analyst

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