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Interactive viewshed basics

Interactive viewsheds are used to determine the visible areas of a 3D view from a given viewpoint. They are calculated against the currently displayed content within a scene, including the ground surface and symbolized features such as buildings and trees.

The viewshed's observer location can be interactively moved through the view. The analysis parameters—the view distance, field-of-view angles, and direction—can be used to model real-world objects such as security cameras or spotters with binoculars. You can also create multiple viewsheds to identify areas that have double, or higher, visibility coverage.

Tip:

Each viewshed object consumes part of your analytical tool display budget, based on its field-of-view angles. Once the display budget has been exceeded, you will receive a notification. You must clear one or more of the existing viewsheds before you can create another.

The analytical results displayed by these tools are temporary and are not saved with the project, nor are they included in map packages. However, their distance, direction, and angle settings and geometry can be exported as point feature classes for further use. If you require the displayed analytical results as data, consider using the geoprocessing tools for visibility instead.

Create an interactive viewshed

The interactive viewshed tool Viewshed Tool is available in the Interactive Analysis gallery in the 3D Exploratory Analysis group on the Analysis tab. As you save templates with custom configurations, they are added to the gallery.

Interactive viewshed creation parameters

OptionDescription

Azimuth

The compass bearing of the viewshed. For example, a value of 180 indicates the observer is looking south.

Tilt

The tilt of the viewshed, where 0 is horizontal and the value increases as the observer looks up. For example, a value of -90 indicates the observer is looking directly down.

Offset

The vertical offset distance to use when creating the observer point for a new viewshed. For example, a value of 6 feet would place the observer at that height above the clicked location in the view.

Horizontal Angle

The horizontal angle of the field of view. For example, a value of 90 indicates a 90-degree view angle for the width of the viewshed.

Vertical Angle

The vertical angle of the field of view. For example, a value of 60 indicates a 60-degree view angle for the height of the viewshed.

Minimum Range

The minimum distance from the observer to analyze. Obstructions closer than the minimum range will appear out of range for the observer.

Maximum Range

The maximum distance from the observer to analyze. Obstructions farther than the maximum range will appear out of range for the observer. For example, a value of 500 feet would mean no analysis results farther than that distance.

Creation methods

MethodDescription

Interactive Placement Viewshed Interactive Placement

Click in the view to place the observer position.

Interactive Orientation Viewshed Interactive Orientation

Click in the view to place the observer position and again to orient the view direction.

Observer from Camera Viewshed From Camera

Create a viewshed using the current camera's viewpoint.

Along a Line Viewshed Along a Line

Use a selected line to create viewsheds based on a travel distance or a percentage along the line.

From Layer Viewshed From Layer

Create viewsheds based on a point layer, where feature attributes can drive parameters such as view direction and distance.

Update an interactive viewshed

To update an existing viewshed, click the observer control with the Viewshed tool to select it. Use the interactive handles to adjust the location and size. You can move the object in x- and y-space or drag the green arrow to move in z-space. An on-screen display dynamically shows the values update. Additional handles are available to adjust the tilt (red), heading (green), and field-of-view distance (blue). The blue arrow changes both the minimum and maximum distances proportionally.

Viewshed selected for updating

If you prefer to manually type values, you can update specific properties for a selected viewshed on the Properties tab in the Exploratory Analysis pane. Browse through selecting each existing viewshed in the scene to make iterative updates. Click All to select and edit all interactive viewshed objects at once.

Delete an interactive viewshed

You can remove a viewshed object by selecting the observer with the Viewshed tool and clicking Delete on the Properties tab. You can also delete a viewshed by pressing the Delete key or by right-clicking and choosing Delete Delete. You can clear all viewsheds at once by clicking the Clear All button Clear All in the 3D Exploratory Analysis group on the Analysis tab.

Interactive viewshed methodology

The interactive viewshed tool is designed for quick interaction within a 3D view. It uses the observer point as a camera viewpoint and takes a raster-based approach for processing what it can see. The result is then projected back into the view, classified into different colors.

This means that the accuracy of the analysis for content in the view is tied to both the relative distance and viewing angles from the observer point. The interactive viewshed results will generally be clearer from higher viewing angles across short distances, and less clear from low viewing angles across large distances.

Viewshed accuracy comparison
Viewshed accuracy drops with larger distances and oblique viewing angles.

The ratio between the minimum and maximum viewing distances also changes the accuracy of the result. It is recommended that the ratio should remain as low as possible. For example, 10 feet to 600 ft (1:60) would be better than 2 feet to 600 feet (1:300).

Viewshed accuracy comparison for distance ratio
Visual inaccuracies can appear as the viewshed's analysis range ratio increases.

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