Working with Water Body Polygons

Water bodies are difficult to model accurately because it is hard to identify and match features due to the uniformity and non-static nature of water. In order to enable PhotoMesh to model and texture a water body successfully, you can define the required water body by drawing or importing a corresponding polygon. PhotoMesh uses this polygon to generate a flat surface over the user-defined water body, and automatically reconstruct any above-water elements – boats, piers, small islands without requiring special user markings. Water bodies can be either of the following:

§ Leveled – A constant water level (i.e., altitude) is set for all points in the water body polygon, to create level water bodies such as seas, lakes, ponds, and pools. This is especially useful for creating a level water body on top of a non-flat terrain or mesh, or for creating a flat water body based on an imported polygon with variable altitude values.

§ Non-Leveled (Sloped) – PhotoMesh segments the water body polygon into multiple flat reconstruction tiles, each of which has a different elevation value based on the average elevation within the specific tile. This option should be selected to create an elevation gradient for water bodies such as rivers, with non-uniform water levels.

Polygon data for both imported polygon layers and manually created ones can be viewed and modified in the Water Polygon list. This list has two tabs: "Polygons" which lists all the individual polygons in the project, and "Layers" tab which lists the polygon layers.

Creating Water Body Polygons

To create a water body polygon:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Polygons tab, select Draw Water Body Polygon or Draw Leveled Polygon .

3. With the cursor in the 3D Window, click to add the first point of the polygon. Click again to add additional points of the polygon until you have marked the entire shape. You must place at least three points to define the polygon.

Note: It is sometimes easier to draw an accurate water polygon over a textured mesh model. After adding the model, rebuild, setting the Build Start From field to Auto, so that the required steps are automatically selected.

Note: When creating a water body polygon, the lines of the polygon should not overlap each other.

Note: It is recommended to keep the number of polygon points to the minimum required to define the shape. Adding unnecessary points may adversely affect performance.

4. Right-click to finish the polygon. The polygon name and water average elevation can be modified in the Water Polygon list. See "Water Polygon List" in this chapter for information. If you want to edit the polygon, see "Editing a Water Body Polygon’s Shape" and "Setting Water Body Polygon Properties" in this chapter for information.

Importing Water Body Polygons

To import a water polygon shapefile or KML layer:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Layers tab, select Import . The Import Water Body Polygon Layer dialog is displayed.

3. Browse to the water polygon layer you want to import, and click Open. If you want to edit the polygons, see "Editing a Water Body Polygon’s Shape" and "Setting Water Body Polygon Properties" in this chapter for information. The water polygons are reprojected to the coordinate system of the current project.

Exporting Water Body Polygons

To export a water polygon layer to a shapefile:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Layers tab, select Export . The Export Water Body Polygon Layer dialog is displayed.

3. Browse to the folder in which to save the layer, type a File name, and click Save. The polygons are exported in Lat-Long coordinate system with the vertical coordinate system of the current project's terrain.

Editing a Water Body Polygon

After modifying a water body polygon, all affected tiles (e.g., tiles that now are intersected by the polygon) require rebuilding from the point cloud step. PhotoMesh will automatically determine what processing is required following the water polygon change, by rebuilding the project from "Auto".

To move a water polygon or modify its shape:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Polygons tab, select the required water polygon, and click Edit Water Body . Then use the polygon mini toolbar to edit the polygon. See "Editing Polylines and Polygons" in this chapter for information on editing polygons.

Selecting Water Body Polygons

Polygons can be selected to perform various commands on them, e.g., jump to a polygon, level/unlevel, or set average elevation.

To select water body polygons:

1. In the Project Tree, select the Water Polygons group.

2. In the 3D Window, click the polygon you want to select, or select the polygon in the Water Polygon list, on the Polygons tab. You can multi-select polygons, either in the Water Polygon list or by using CTRL-click or SHIFT-click in the 3D Window.

Note: If you turned on global selection, you can select a polygon in the 3D Window even without first selecting the Water Polygons group in the Project Tree as long as the polygons are visible in the 3D Window.

See "Showing and Hiding Group Items" and "Selecting Items Using the Item List" in the "Using the Project Tree and Item List" chapter and "Selecting Objects in the 3D Window" in the "Basic Concepts" chapter for information.

Navigating to a Water Body Polygon

To fly or jump to a water body polygon:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Polygons tab, right-click the required polygon, and select Fly To/Jump To.

Setting Water Body Polygon Properties

Water body polygon data (e.g., average elevation and elevation offset) can be viewed or modified in the Water Polygon list. See "About the Item List" in the "Using the Project Tree and Item List" chapter for information on working with the Water Polygon list.

To display and modify water body polygon properties:

1. In the Project Tree, select the Water Polygons group.

2. For group/layer properties: In the Water Polygon list, click the Layers tab, and modify the property value as required. See "Water Polygon List – Layers Tab" in this chapter for more information.

3. For individual polygon properties: In the Water Polygon list, click the Polygons tab, select the row of the required polygon, and then click in the required column, and modify its properties as required. See "Water Polygon List" in this chapter for more information.

Note: You can also search the list for the required polygons. See "Selecting Items Using the Item List" in the "Basic Concepts" chapter for information.

Water Polygons List – Layers Tab

The properties in the Water Polygon list – Layers tab apply to all polygons in the layer.

Property	Description
Selection	Select the check box to select the layer for editing.
Name	Name of the water body layer in the Water Polygons list. All manually created polygons are saved in the same layer.
Fill Color	Fill color for all the water body polygons in the layer.
Visible	Select the check box to show the layer’s polygons in the 3D Window.
Excluded	Select the check box to exclude the water body layer from the project.
Leveled	Select the check box to set a constant water level (i.e., altitude) for all points in all the water body polygons in the layer, to create level water bodies such as seas, lakes, ponds, and pools. This is especially useful for creating level water bodies on top of a non-flat terrain or mesh, or for creating flat water bodies based on imported polygons with variable altitude values. If the check box is cleared, PhotoMesh segments the water body polygons into multiple flat reconstruction tiles, each of which has a different elevation value based on the average elevation within the specific tile. This option should be selected to create an elevation gradient for water bodies such as rivers, with non-uniform water levels.
Elevation Offset	Elevation offset from the current elevation value applied to entire water body layer.
Coordinate System	Coordinate system of all the water polygons in the layer (Read-only for manually created polygons). When water polygon layers are imported, they are reprojected to the terrain database coordinate system. Note: When the coordinate system is changed, the layer is reloaded causing all manual modifications, e.g., editing of the polygon or changes to elevation offset, to be lost.
Original Source Path	Original source path from where the water body layer was imported (Read-only).

Water Polygon List – Polygons Tab

In the Water Polygon list – Polygons tab, you can view and set certain polygon properties, as well as set polygon visibility and inclusion in the project. See "About the Item List" in the "Using the Project Tree and Item List" chapter for information on working with the polygon list.

Property	Description
Selection	Select the check box to select the polygon for editing. You can select multiple polygons to perform actions on multiple polygons.
Name	Name of the water polygon.
Layer	Name of the water polygon layer. All manually created polygons are saved in the same layer. Click the three dots to open the Layers tab to edit the layer name.
Visible	Select the check box to show the polygon in the 3D Window.
Excluded	Select the check box to exclude the polygon from the project. The polygon continues to display in the 3D Window.
Leveled	Select the check box to set a constant water level (i.e., altitude) for all points in the water body polygon, to create level water bodies such as seas, lakes, ponds, and pools. This is especially useful for creating a level water body on top of a non-flat terrain or mesh, or for creating a flat water body based on an imported polygon with variable altitude values. If the check box is cleared, PhotoMesh segments the water body polygon into multiple flat reconstruction tiles, each of which has a different elevation value based on the average elevation within the specific tile. This option should be selected to create an elevation gradient for water bodies such as rivers, with non-uniform water levels. If a water polygon is leveled, all its nodes are set to the elevation of the first node drawn. Note: If you want to level or unlevel multiple polygons, multi-select the required polygons. Then right-click in the Water Polygon list, and select Level/Unlevel. Unleveling allows you to set different elevations for each polygon node. See "Selecting Water Body Polygons" in this chapter for more information.
Average Elevation	The average elevation of the water polygon. When this value is edited, PhotoMesh proportionally adjusts the elevation value of each of the individual nodes, so that the ratio between node elevations is still maintained. Note: If you want to set the average elevation of multiple polygons, multi-select the required polygons. Then right-click in the Water Polygon list, and select Set Average Elevation. You can also modify the average elevation of multiple polygons by a specified delta. To do so, multi-select the required polygons. Then right-click in the Water Polygon list, and select Set Elevation Delta. See "Selecting Water Body Polygons" in this chapter for more information.

Deleting Water Body Polygon Layers

To delete a polygon layer:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Layers tab, right-click the required polygon, and select Delete.

Deleting Water Body Polygons

To delete a polygon from a layer:

1. In the Project Tree, select the Water Polygons group.

2. In the Water Polygon list, on the Polygons tab, right-click the required polygon, and select Delete.