Line of sight objects determine if one or more targets are visible from a given observer's viewpoint in a scene. They are calculated against the currently displayed content in the scene, including the ground surface and symbolized features such as buildings and trees, and are therefore dependent upon the level of detail being used for the camera's view position.
Both the line of sight observer and target locations can be interactively moved through the scene. The analysis parameters, vertical offsets, and view distances can be used to model real-world objects such as a person's height and binocular range. A line of sight analysis can be based on a single observer with one or more targets created from a selected path or an existing line layer.
Note:
Each line of sight object consumes part of your analytical tool display budget. Once the display budget has been exceeded, you must remove one or more of the existing lines of sight before you can create another.
The analytical results displayed by the line of sight tool are temporary and are not saved with the project, nor are they included in map packages. However, their distance settings and geometry can be exported out as a line feature class in the default geodatabase of the project for further use. To save analytical results as data, use the geoprocessing tools for visibility instead.
Create an interactive line of sight object
To create an interactive line of sight object in a scene, on the Analysis tab, in the Workflows group, open the Exploratory 3D Analysis menu and click Line of Sight 
. This opens the Exploratory Analysis pane and activates the Interactive Placement line of sight tool. See the following sections to understand the creation parameters and methods available in the tool.
Interactive line of sight creation parameters
Interactive line of sight creation parameters are described in the following table:
| Creation parameters | Description |
|---|---|
Observer Vertical Offset | The vertical offset distance to use when creating the observer point for a new line of sight. For example, a value of 6 feet places the observer 6 feet above the clicked location in the scene. |
Observer Minimum Distance | The minimum distance from the observer to analyze. Obstructions closer than the minimum distance do not participate in the analysis. |
Observer Maximum Distance | The maximum distance from the observer to analyze. Obstructions farther than the maximum distance do not participate in the analysis. |
Target Vertical Offset | The vertical offset distance applied to the clicked location when creating a target point. |
Creation methods
There are four methods for creating an interactive line of sight object:
| Creation methods | Description |
|---|---|
Interactive Placement | Click in the scene to place the observer position. Click again to place one or more targets. This is the default method. Use this creation method for general exploratory investigation of sight lines within a scene. |
Observer From Camera | Position the view to set the camera as the observer. Click in the scene to place one or more targets. Use this creation method to create line of sight observers from important viewpoints, such as bookmarks. |
Targets Along a Line | Use a selected line to create a line of sight object based on a number of targets or a segment length. Multiple continuous lines are processed as a single route where possible. Use this method to determine visibility along a route. |
From Layer | Automatically generate lines of sight based on a line layer where feature attributes populate parameters such as minimum and maximum distances. Previously exported analysis objects can be revisited using this method. |
Update an interactive line of sight object
To update the analysis area for an existing line of sight, select the observer or target point in the scene with the Line of Sight tool and use the interactive handles to adjust the location. You can reposition the objects in the x- and y-planes or drag the green arrow to move in the z-plane. A corresponding edit overlay is an optional on-screen display of values that reflect which properties you are updating. You can also type a new value directly in it.
Select a line of sight object or target
To modify the global property values for an individual line of sight object, it must first be selected. Select a single line of sight either by clicking the observer or target point in the scene or using the following options available in the navigation box at the top of the Properties tab:
Select Next Object
—Cycle the selection forward through
the existing lines of sight observers in the scene. When the desired line of sight object is
selected, you can update its values and
colors.Select Previous Object
—Cycle the selection in reverse order through
the existing lines of sight observers.Select Next Target
—Cycle the selection forward through
the existing targets for the selected line of sight observer in the scene. When the desired target is
selected, you can update its values and
colors.Select Previous Target
—Cycle the selection in reverse order through
the existing targets for the selected line of sight observer.Select All—All line of sight objects in the scene are selected. Changes to any property values are applied to all line of sight objects.
- Delete
—The selected line of sight objects are removed from the scene and the next object is selected.
Clear a selection by clicking away from the line of sight objects in the scene with the creation method tool still active.
Update using the selection handles
When a line of sight object is selected, interactive handles appear so you can modify it. You can change the following properties for a line of sight:
- Drag the positioning circle for the observer point to a new location, updating the x- and y-values.
- Drag the observer's vertical green arrow handle to adjust its elevation (z-value).
- Drag the target's vertical green arrow handle to adjust its elevation (z-value).
Note:
The observer and target control points honor the option to navigate below ground for the scene. Therefore, to move control points below the ground elevation surface, you must enable this capability. Select the elevation surface in the Contents pane, and on the Elevation Surface Layer tab in the Surface group, check the Navigate Underground option. This property applies a 2-meter offset from the ground to ensure the point remains above ground when the scene changes the ground surface level of detail.
Update using the Properties tab
Use the Properties tab in the Exploratory Analysis pane to iteratively select your analysis objects, provide necessary modifications, or, optionally, click Delete to remove an object. To clear a selection, you must click away from the object in the scene.
Global properties
Global properties affect the appearance of all existing and future view dome objects. Expand the Global Properties heading to the width of sight lines and change the colors used to symbolize the line of sight object, including the wireframe color and nonvisible areas.
The line of sight properties you can update include the following:
- Minimum and maximum distance values for the analysis range from the observer point
- Click the Extend lines to maximum distance option to extend the lines of sight past their target to their maximum distance to show the remaining range.
- Click the Show edit overlay option to add a control to the scene that dynamically updates values as you modify the shape of the selected line of sight object. You can also directly type each of the handle values.
- Click the Show intersection distance option to display labels in the scene showing the distance from the observer to the first blocking intersection point for each line of sight object. The values are shown in the Maximum Distance unit selected during creation.
At any time, the Restore Defaults button can be used to return all global properties to their default values.
| Property | Description |
|---|---|
Line Width | The width of the lines connecting the observer and target points |
Visible Color | The color representing what the observer can see |
Not Visible Color | The color from the first obstruction point to the maximum distance representing what the observer cannot see |
Out of Range Color | The color representing visibility farther than the maximum distance |
Wireframe Color | The color of the wireframe overlay that surrounds the line of sight observer and tethers it to the ground |
Delete an interactive line of sight object
You can delete a line of sight object from a scene by selecting the observer point with the active view dome tool. Then, in the Exploratory Analysis pane, on the Properties tab, click Delete .
To delete all line of sight objects at once, as well as any other exploratory analysis objects, open the Exploratory 3D Analysis menu in the Workflows group on the Analysis tab, and click Clear All .