Viewshed Point Editor Tool

Overview

The Viewshed Point Editor Tool is a specialized visibility analysis preparation system for creating and managing observation points used in viewshed analysis. It supports both automated random point distribution within selected polygons and manual point placement, with configurable point counts and bearing angles.

Interface Access

Tool Launch

1. Find Viewshed Points Editor icon
2. Open editor panel

Panel Layout

The panel is organized into three sections:

Section	Contents
Draw row	Select Target Shape, Draw Reference Point, and Reset buttons
Actions row	Generate (random points) and Save buttons
Parameters	Total area display, Max Points indicator, Num of Points input, Angle input
Delete section	Vis Num input and Delete button (outlined in red)

Target Layer Selection

Before selecting shapes, choose the target layer from the Target Layer dropdown at the top of the panel.

• The dropdown refreshes automatically when clicked, showing all currently visible polygon layers
• Supported layer types:
  • FeatureLayers with polygon geometry
  • MapImageLayers that contain polygon sublayers
• Changing the selection deactivates any active selection mode

Point Creation

Selecting Target Shapes

Target shapes define the area within which random points are generated.

1. Choose a layer from the Target Layer dropdown
2. Click the Select Target Shape button (cursor icon) to activate selection mode — the button icon changes to indicate active state
3. Click polygons on the map to select them (highlighted with a target symbol)
4. Click a selected polygon again to deselect it (toggle behavior)
5. Click the Select Target Shape button again to deactivate selection mode

TIP

The Total (ha) readout below the toolbar updates as you select polygons, showing the cumulative area of all selected shapes. This value determines the maximum number of points available.

MapImageLayer cycling

When clicking on a MapImageLayer location with multiple overlapping polygons, each subsequent click on the same spot cycles to the next polygon. A notification shows which feature was selected (e.g., "feature 2 of 3").

Random Generation

Generates evenly distributed viewshed points within the selected target area.

1. Select at least one target shape (see above)
2. Configure parameters:
   • Num of Points — number of points to generate (1 to max)
   • Angle — rotation angle for the point grid (0–180 degrees)
3. Click Generate

Max Points limit

The maximum number of points depends on the total area of selected shapes:

• Area < 50 ha → maximum 10 points
• Area ≥ 50 ha → maximum 15 points

The Max Points indicator on the panel updates dynamically as you select shapes. Increasing the selected area unlocks more points.

WARNING

If the selected area is too small or irregular to fit the requested number of points, a warning shows how many points could be generated (e.g., "Only 8 out of 10 points could be generated due to space constraints").

Generating new random points clears any previously generated reference points before creating the new set.

Manual Addition

Place individual reference points directly on the map.

1. Click the Draw Reference Point button (pin icon) to activate draw mode — the button icon changes to indicate active state

   

2. Click anywhere on the map to place points

3. Each click adds a new reference point (duplicate points at the same location are ignored)

4. Click the Draw Reference Point button again to deactivate draw mode

INFO

Manual points and randomly generated points can be combined before saving.

Reset

Click the Reset button (reset icon) to clear all selected target shapes and reference points and deactivate any active selection or drawing mode.

Point Management

Saving Points

Saves all current reference points to the database as a new viewshed point set.

1. Draw or generate reference points on the map

2. Click the Save button

   

3. On success, a notification shows the assigned viewshed point number (e.g., "Viewshed points with number 42 have been saved successfully")

WARNING

• Save requires at least one reference point — clicking Save with no points shows an error
• If more than 15 reference points are drawn, only the first 15 are saved; a warning is shown

After saving, the reference point graphics and target shapes are cleared from the map automatically.

Point Deletion

Delete an existing viewshed point set by its visibility number.

1. Enter the visibility number in the Vis Num field

   

2. Click the Delete button (trash icon) — this button is disabled until a vis number is entered

INFO

The Delete button only enables when a vis number is entered in the field.

Delete Confirmation Dialog

When you click the Delete button, a confirmation dialog appears to prevent accidental deletion.

Dialog Details:

• Heading: "Delete Viewshed Points?"
• Kind: Danger (red indicator)
• Modal: Yes — you must respond before continuing
• Content: Displays the viewshed point number being deleted and warns that the action cannot be undone
• Footer Buttons:
  • Cancel (left) — closes the dialog without changes
  • Delete (right, red) — permanently removes the viewshed points

The dialog prevents closing via the Escape key or clicking outside, ensuring you make an explicit choice.

Troubleshooting

Issue	Solution
No layers appear in the Target Layer dropdown	Ensure at least one polygon FeatureLayer or MapImageLayer with polygon sublayers is visible on the map
Select Target Shape button is hidden	The button only appears when a target layer is selected in the dropdown
Generate button does nothing	Select at least one target shape first — "Please select at least one target shape first" error appears if none selected
Fewer points generated than requested	The selected area may be too small or irregular; try selecting a larger target area or reducing Num of Points
Max Points shows 10 instead of 15	Selected area is below 50 ha; select more polygons to increase total area above 50 ha
Save fails with no error	Ensure at least one reference point is drawn or generated before saving
Only 15 points saved despite drawing more	The system saves a maximum of 15 points; a warning is shown when this limit is exceeded
Delete button is greyed out	Enter a visibility number in the Vis Num field first
Features not visible after saving	Check that the Viewshed Points layer is visible in the layer panel

Video Tutorials

Random Point Generation

Manual Point Creation

Point Deletion Tutorial

See Also

• Plot Random Tool - Random plot generation using polygon boundaries
• Concepts: FeatureLayer vs MapImageLayer - Understanding layer types used for polygon selection
• Advanced Editor - Geometric operations for spatial analysis

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