Determines the raster surface locations visible to a set of observer features using geodesic methods.
<DIV STYLE="text-align:Left;"><DIV><DIV><UL><LI><P><SPAN>This tool performs two types of visibility analysis, Frequency and Observers, which can be set using the analysisType parameter. </SPAN></P></LI><LI><P><SPAN>To ensure the accuracy of the output, assign a vertical coordinate system to the input raster, if it does not already have one. </SPAN></P></LI><LI><P><SPAN>When the input raster needs to be resampled, the bilinear technique will be used. An example of when an input raster may be resampled is when the output coordinate system, extent, or cell size is different from that of the input. </SPAN></P></LI><LI><P><SPAN>To enhance performance, you can explicitly set the maximumViewingDistance parameter to a value that represents the maximum viewing distance of interest for your analysis. </SPAN></P></LI><LI><P><SPAN>By default, the optimizeFor parameter uses the Accuracy option, which gives the most accurate output. To improve the performance of the tool in terms of processing time, use the Speed option. </SPAN></P></LI><LI><P><SPAN>The observer parameters related to height, such as observersHeight, observersElevation, targetHeight, can be specified as a linear unit or as a field. During the calculation, the linear unit value will be converted internally to the Z unit of the input raster. However, if the linear unit is unknown or a numeric field is specified, the value is assumed to be in the Z unit of the input raster. </SPAN></P></LI><LI><P><SPAN>The observer parameters related to viewing distances, such as the maximumViewingDistance and the minimumViewingDistance parameters, can be specified as a linear unit or as a field. During the calculation, the linear unit value will be converted internally to the XY units of the input raster. However, if the linear unit is unknown or a numeric field is specified, the value is assumed to be in the XY unit of the input raster. </SPAN></P></LI></UL></DIV></DIV></DIV>
| Parameter | Explanation |
|---|---|
| inputElevationSurface | <DIV STYLE="text-align:Left;"><P><SPAN>The elevation surface to use for calculating the viewshed. </SPAN></P></DIV> |
| inputObserverFeatures |
The point features that represent the observer locations when calculating the viewsheds. |
| outputName | <DIV STYLE="text-align:Left;"><P><SPAN>The name of the output raster service. </SPAN></P></DIV> |
| optimizeFor (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>The optimization method to use for calculating the viewshed. </SPAN></P><UL><LI><P><SPAN>SPEED—This method optimizes the processing speed, trading some accuracy in the result for higher performance. This is the default.</SPAN></P></LI><LI><P><SPAN>ACCURACY—This method is optimized for accuracy in the results, at the expense of a longer processing time. </SPAN></P></LI></UL></DIV> |
| analysisType (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>Specifies the type of visibility analysis you wish to perform, either determining how visible each cell is to the observers, or identifying for each surface location which observers are visible. </SPAN></P><UL><LI><P><SPAN>FREQUENCY—The output records the number of times that each cell location in the input surface raster can be seen by the input observation locations (as points or as vertices for polyline observer features). This is the default. </SPAN></P></LI><LI><P><SPAN>OBSERVERS—The output identifies exactly which observer points are visible from each raster surface location. The allowed maximum number of input observers is 32 with this analysis type. </SPAN></P></LI></UL></DIV> |
| verticalError (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>The amount of uncertainty in the surface elevation values. </SPAN></P></DIV> |
| refractivityCoefficient (Optional) |
The coefficient of the refraction of visible light in air. |
| maximumViewingDistance (Optional) |
This is a cutoff distance, where the computation of visible areas stops. |
| minimumViewingDistance (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>This is a distance where the computation of visible areas begins. </SPAN></P></DIV> |
| viewingDistancesAre3D (Optional) | <DIV STYLE="text-align:Left;"><DIV><P><SPAN>Specify whether the minimumViewingDistance and maximumViewingDistance parameters are measured in a three-dimensional way or a simpler, two-dimensional way. </SPAN></P><UL><LI><P><SPAN>False - The viewing distances are to be interpreted as a 2D distance. </SPAN></P></LI><LI><P><SPAN>True - The viewing distances are to be interpreted as a 3D distance. </SPAN></P></LI></UL></DIV></DIV> |
| observersElevation (Optional) |
This is the elevation of your observer locations. |
| observersHeight (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>This is the height used for your observer locations. </SPAN></P></DIV> |
| targetHeight (Optional) |
This is the height of structures or people on the ground used to establish visibility. |
| horizontalStartAngle (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>The start angle of the horizontal scan range. </SPAN></P></DIV> |
| horizontalEndAngle (Optional) |
The end angle of the horizontal scan range. |
| verticalUpperAngle (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>The upper vertical angle limit of the scan relative to the horizontal plane. </SPAN></P></DIV> |
| verticalLowerAngle (Optional) |
The lower vertical angle limit of the scan relative to the horizontal plane. |
| outputAboveGroundLevelRasterName (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>The name of the output aboveground-level (AGL) raster. </SPAN></P></DIV> |
| outputObserverRegionRelationshipTableName (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>The output table for identifying the regions that are visible to each observer. </SPAN></P></DIV> |
| context (Optional) | <DIV STYLE="text-align:Left;"><P><SPAN>Specifies the analysis environments. </SPAN></P></DIV> |
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