Viewshed Analysis is a way to understand visibility across a 3D scene. It identifies which parts of the surrounding environment can be seen from a selected location, taking into account the terrain and buildings that may obstruct the view.

This is particularly useful when assessing the visual impact of a proposed development, studying sightlines from public spaces or buildings, and understanding how new structures might affect views across an area. For example, an analysis can help establish whether a proposed building would be visible from a nearby park, how much of a landmark can be seen from a particular location, or which areas are overlooked by a development.

An analysis can use a single observer point or multiple observers to compare visibility from different locations. The results can then be explored through different visualisations, showing visible and hidden areas, overlapping views and proximity to the nearest observer.

Once created, the analysis can be saved to the scene, styled and reviewed in Scene Manager.

Using the Viewshed

1. Open Viewshed Analysis
   Open the Toolbox from the left toolbar and select Viewshed Analysis. The observer setup panel opens, where observer points can be added and configured.
2. Add observer points
   Observers define the locations from which visibility is calculated. There are two ways to add them, and both methods can be combined within the same analysis.
3. Using a viewpoint collection
   Select a viewpoint collection from the setup panel. Each viewpoint in the collection is added as an observer, with its position and camera settings carried across.
4. Placing observers in the scene
   Click directly in the 3D scene to place an observer at the selected location. Additional observers can be added in the same way.

Configure observers

Each observer has its own position and viewing parameters. The observer dropdown at the top of the setup panel switches between the available observers.

An observer can be repositioned using the movement gizmo in the scene, or configured by editing its values directly in the panel.

The following parameters are available:

• Range: Maximum viewing distance, in metres.
• Horiz. FOV: Horizontal field of view, in degrees.
• Vertical FOV: Vertical field of view, in degrees.
• Pitch: Vertical viewing angle, determining how far the observer looks up or down.
• Bearing: Horizontal viewing direction, in degrees.

Observers imported from a viewpoint collection remain linked to their original viewpoints. To edit their viewing parameters independently, unlink the observer first.

To remove an observer, click the X next to the observer dropdown.

Once all observers have been positioned and configured, select Save to Scene to create the viewshed analysis.

View and style the results

Saved viewsheds appear in Scene Manager. Selecting a viewshed opens its Properties Panel, where the display settings and visualisation can be adjusted.

Settings

The Settings tab contains the main display options:

• Visibility: Shows or hides the viewshed in the scene.
• Display on Legend: Controls whether the viewshed appears in the scene legend.
• Visualised data field: Determines which visibility data is displayed.

The available visualisation options are:

• Visible / Not visible: Distinguishes between areas that can and cannot be seen from the observer points.
• Cumulative visibility: Highlights areas visible from multiple observers, showing where their views overlap.
• Proximity to nearest observer: Displays the distance from each visible area to its closest observer.

Adjust colours

The viewshed colours can be customised through the scene legend. Select a category to open its colour settings, where the fill colour, opacity, hex value and outline can be adjusted.

Review and edit a viewshed

An existing viewshed can be returned to the observer setup using Re-adjust. This opens the original configuration, allowing observer positions and viewing parameters to be changed before saving the analysis again.

The Properties Panel also contains two tabs with additional information:

Details

Displays an overview of the analysis, including the number of observer points, creation date, creator and description.

Observers

Lists the individual observers and their configuration values, including:

• AOD
• Eastings and Northings
• Range
• Horizontal and vertical field of view
• Bearing
• Pitch