Viewshed

The Viewshed tool in SiEGA allows users to visualize line-of-sight coverage from a specific point in a 3D environment. By placing a "viewshed actor" into the scene, users can see which areas are visible or obstructed from that vantage point, making it useful for applications like urban planning, surveillance positioning, and visibility testing in city models. The tool is interactive, real-time, and highly customizable, enabling control over field of view, distance, orientation, and resolution.

How To Use

To activate Viewshed Mode, open the Actions menu and click the Viewshed button. Once activated, movement controls switch to WASD keys for navigation, and left-click + drag lets you pan the camera. This changes the user interaction mode to better support precise placement and manipulation of the viewshed actor.

After enabling Viewshed Mode, a configuration panel appears on the right side of the screen. To begin, click “Place a Viewshed Actor” to spawn the interactive object that determines the center point of your visibility analysis. This actor will define the origin of the viewshed.

Once the button is clicked, a blue crystal-shaped actor will attach to your cursor. Move your cursor to the desired location in the scene, then click once to place it. This actor serves as the origin point for calculating visibility.

After placing the actor, drag your mouse to define the initial extent of the viewshed. The distance you drag will determine how far the field of visibility will project from the actor’s location.

With the actor in place, you can fine-tune the viewshed field using the sliders on the right panel:

• Field of View: Controls the horizontal angle of visibility.

• Max Distance: Defines how far the viewshed extends from the origin.

• Ratio: Adjusts the vertical compression or expansion of the view cone.

• View Height: Raises or lowers the actor's origin point.

• Yaw: Rotates the viewshed horizontally.

• Pitch: Adjusts the vertical angle.

• Resolution: Sets the precision and quality of the viewshed visualization.

To reposition the viewshed actor, simply click “Place a Viewshed Actor” again. This will remove the current actor and attach a new one to your cursor, allowing you to place it at a new location.

To exit Viewshed Mode, click the “X” button at the top of the configuration panel. This will close the panel and return the camera to fly mode, restoring normal navigation controls and disabling the visibility overlays.