Raster Viewshed
Open Table of Contents ToolBox Implementation
Calculates the visibility from a set of observer points to each of the cells of the output raster based on the input surface raster.  

Inputs:

  • A point dataset (Observers). The attribute table can have a numeric field which values will indicate the offset of the observers above the terrain.
  • A raster dataset representing the surface for which the analysis will be performed.
  • A field in the point feature class that will indicate the offset of the observer above the surface.
  • A number that will indicate the offset of the target above the surface.
  • Cutoff distance (optional) - how far an observer can see
  • Options (see Line of Sight discussion)
    • Apply Earth curvature correction
    • Apply air refraction corrections
    • Apply radio wave corrections.

Outputs:

  • An integer raster. Each cell will have as a value the number of observers from which this cell is visible.

Example:
Viewshed from 5 observers symbolized with unique value - the number of observers that can see each cell.
Viewshed from 5 observers classified in 2 classes:
  • 0 - Non-visible.
  • >0 - Visible

Notes:

  • Initially the name of the output raster defines the raster format
    • no extension specified - ESRI binary GRID
    • .img extension (for example raster1.img) - ERDAS IMAGINE image.
    • .tif extension (for example raster1.tif - Tagged Image File Format (TIFF) image.
  • The initial output raster format can be changed by selecting the desired output in the dialog.
  • Currently only file based rasters are supported. Rasters cannot be stored in a GeoDatabase. After you get the desired result, you can export the raster to a GeoDatabase using the standard ArcGIS tools.
  • The input  point feature class and raster must be in the same projected coordinate system.

ToolBox implementation

Command line syntax

ETS_GPViewshed <Observers> <Input Raster>  <Out Raster> <Observer Offset Field> <Target Offset> {Use Earth Curvature}  {Refraction Correction} {Radio Waves Correction} {Cutoff Distance}

Parameters

Expression Explanation
<Observers> A Point layer or feature class
<Input Raster> A  Raster dataset or Raster layer
<Out Raster> A String - the full name of the output raster (A raster with the same full name should not exist). The output raster type depends on the extension of the output file(see Notes above)
<Observer Offset Field> A String representing the name of the field which values are going to be used as offset of the observers above the raster.
<Target Offset> A Double indicating the offset of the target above the surface.
 {Use Earth Curvature} A Boolean
 {Refraction Correction} A Double representing the air refraction coefficient - Default value = 0.13
 {Radio Waves Correction} A Double representing the radio waves correction coefficient - Default value = 1.333333
 {Cutoff Distance} A Double representing the Cutoff distance.

Scripting syntax

ETS_GPViewshed (Observers, Input Raster,  Out Raster, Observer Offset Field, Target Offset, Use Earth Curvature, Refraction Correction,  Radio Waves Correction, Cutoff Distance)

See the explanations above:
<> - required parameter
{} - optional parameter

All ESRI products mentioned are trademarks of Environmental Systems Research Institute, Inc.
Copyright: Ianko Tchoukanski