You can use the Line of sight tool 
to perform 3D visibility analysis from an observer to multiple target points. The visibility between the observer and
multiple target points is calculated using the currently
displayed content in the view, including ground, integrated meshes,
and 3D objects, such as buildings or trees.
The line of sight analysis appears as lines and spheres: green lines are the visible part that the observer can see, and red lines are the occluded part. Also, green spheres indicate visible targets in which the full line is green, and red spheres indicate the occluded targets. When the line of sight can't be calculated, it is displayed with a gray color. This occurs when either the target or the observer are not in the view, or when neither of them are in the view.
Create a line of sight layer
To create a line of sight layer, complete the following steps:
- Click Add Layers
on the Designer toolbar. - Click Line of sight to open the Line of sight pane.
- Click in the scene to place an observer point.
- Drag and click to place a target.
- Click and drag to place more targets.
- Click Stop anytime to stop placing points.
- To adjust the line of sight or targets, do any of the following:
- Click and drag any of the points to adjust the line of sight.
- Click Continue to place more target points.
- Click New to reset the line of sight.
- Right-click a target to remove it.
- Click Done when you are finished.
A new line of sight layer is added to the layer list in the Layer Manager pane.
Modify an existing line of sight layer
To modify an existing line of sight layer, complete the following steps:
- Click Layer Manager
to open the Layer Manager pane. - Select the line of sight layer or click Options
and click Edit Line of sight to open the Line of sight pane. - To edit a line of site or the targets, do any of the following:
- Click and drag any of the points to adjust the line of sight.
- Click Continue to place more target points.
- Click New to reset the line of sight.
- Right-click a target to remove it.
- Click Stop anytime to stop placing points.
- Click Done when you are finished.
- Click Cancel to return to the Layer Manager pane.