Instructions for use
Viewshed Analysis is to extract the visible area within a given length range and direction range based on a certain relative height for one or more observation points on the surface of Raster Data, and output the Analyst Result as a Raster Dataset.
- As one of the components of the total elevation of the observation point, the Append: value has an important impact on the Analyst Result of the viewfield. Therefore, it is necessary to understand the surface elevation value of the observation point and the Append: value to ensure that the Analyst Result is more in line with the actual situation.
- View Radius: The default value is 0, which means to search within the entire analysis area. The unit of View Radius: is consistent with the Raster Dataset participating in the analysis.
- When there are multiple observation points, the Analyst Result of the visual field can be the union or intersection of the visual areas of all the observation points. When the "Common viewshed" "parameter is used, it means that the intersection of the visible areas of all the observation points is taken, otherwise, the union of the visible areas of all the observation points is taken.
Function entrance
- On the Spatial Analysis tab-> Raster Analysis-> Surface Analysis-> Viewfield;
- Toolbox-> Raster Analysis-> Surface Analysis-> Visibility Analysis-> Viewshed Analysis.
Operating instructions
- Specify observation point: it can be added by mouse click, or directly Import Point Dataset as observation point. The selected observation point is highlighted in blue on the map. An observation point is stored as a record.
- On the Visibility Analysis dialog, click the Click to Add "button, mouse status changes to add status, and you can select viewpoint points on the grid surface by clicking. Use the import function Import View Point
- in the toolbar. The imported Point Dataset must include Append: Field, View Radius: Field, Start Angle Field, Observation Angle Field.
When there are multiple observation points, record parameter information selected by Batch Settings button Uniform Settings, including Append: value, View Radius:, Start Angle, and View Angle:.
- Viewfield Analysis Settings:
Append: The relative height of the view point above the grid surface. For example, if the elevation of the selected point on the map is 430 meters and the Append: value is 100 meters, the elevation of the observation point is 530 meters. The default Append: is 0.
View Radius: Length range used to set Viewshed Analysis. The circular area with the observation point as the center and this value as the radius is the observation area of the visible field. The system defaults to 0, which indicates the maximum range of using the grid table Region Dataset.
Start Angle: Used to set the Start View Angle of the Viewshed Analysis direction, in degrees. Clockwise rotation at 0 degrees due north. When specified as negative or greater than 360 degrees, it will be automatically converted to the range of 0-360 degrees.
View Angle: It is used to set the View Angle: of Viewshed Analysis, which is in one-to-one correspondence with the Start Angle, and the value range is 0-360 degrees. The default is 360 degrees.
- Other Analysis Settings, including Analyst Result, Common View, whether to Result DatasetAdd to Current Map Window, and so on.
Datasource: lists the Datasources in the Current Workspace. You need to select the Data source where the Analyst Result will be saved.
Dataset: Set the Dataset for result saving. The Dataset Name to be saved by the input result is required.
Common viewshed: When there are multiple observation points, you need to set whether the viewshed is the union or intersection of the observation points. If "Common viewshed" "is checked, it means that the intersection of all the observation points will be taken as Analyst Result, otherwise, the union will be taken.
Add result to current map: If this option is selected, it means that Result Dataset will be automatically Add to Current Map Window after the analysis is completed; otherwise, it will not be automatically added.
Auto Close when finished: If this option is selected, the dialog box will be Auto CloseViewshed Analysis after the analysis is completed; otherwise, it will not be closed.
- Complete the Viewshed Analysis operation, and the results are shown as follows:
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| Figure: Viewshed Analysis result |
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