Observer Points (Spatial Analyst)

Summary

Identifies which observer points are visible from each raster surface location.

Learn more about how Observer Points works

Usage

Syntax

ObserverPoints (in_raster, in_observer_point_features, {z_factor}, {curvature_correction}, {refractivity_coefficient})
ParameterExplanationData Type
in_raster

The input surface raster.

Raster Layer
in_observer_point_features

The point feature class that identifies the observer locations.

The maximum number of points allowed is 16.

Feature Layer
z_factor
(Optional)

Number of ground x,y units in one surface z unit.

The z-factor adjusts the units of measure for the z units when they are different from the x,y units of the input surface. The z-values of the input surface are multiplied by the z-factor when calculating the final output surface.

If the x,y units and z units are in the same units of measure, the z-factor is 1. This is the default.

If the x,y units and z units are in different units of measure, the z-factor must be set to the appropriate factor, or the results will be incorrect. For example, if your z units are feet and your x,y units are meters, you would use a z-factor of 0.3048 to convert your z units from feet to meters (1 foot = 0.3048 meter).

Double
curvature_correction
(Optional)

Allows correction for the earth's curvature.

  • FLAT_EARTH No curvature correction will be applied. This is the default.
  • CURVED_EARTH Curvature correction will be applied.
Boolean
refractivity_coefficient
(Optional)

Coefficient of the refraction of visible light in air.

The default value is 0.13.

Double

Return Value

NameExplanationData Type
out_raster

The output raster.

The output identifies exactly which observer points are visible from each raster surface location.

Raster

Code Sample

ObserverPoints example 1 (Python window)

This example identifies exactly which observer points are visible from each raster surface location.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outObsPoints = ObserverPoints("elevation","observers.shp", 1, "CURVED_EARTH", 0.13)
outObsPoints.save("C:/sapyexamples/output/outobspnt01")
ObserverPoints example 2 (stand-alone script)

This example identifies exactly which observer points are visible from each raster surface location.

# Name: ObserverPoints_Ex_02.py
# Description:  Identifies exactly which observer points are visible 
# from each raster surface location.
# 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
inRaster = "elevation"
inObsPoints = "observers.shp"
zFactor = 1
useEarthCurv = "CURVED_EARTH"
refractionVal = 0.13

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

# Execute ObserverPoints
outObsPoints = ObserverPoints(inRaster, inObsPoints, zFactor, 
                              useEarthCurv, refractionVal)

# Save the output 
outObsPoints.save("C:/sapyexamples/output/outobspnt02")

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