Build Polygons Command
The Build Polygons command allows the user to create polygons from the existing polylines drawn on the Map View. This is useful when a complex boundary, such as a watershed boundary, study area boundary, or land use zone, is too large or intricate to digitize as a single polygon and needs to be constructed in stages using multiple polyline segments. For example, the user might want to digitize a complex watershed boundary in stages, in order to break down the work into manageable tasks.
Follow the steps below to use the Build Polygons command:
- From the Map Edit ribbon menu, select the Build Polygons command.
- The Build Polygons dialog box will be displayed.
The following sections describe how to use the Build Polygons command and interact with the above dialog box.
Selecting Polylines/Polygons
The Select Polylines/Polygons section allows the user to select the polylines/polygons to create new polygons by digitizing the polyline/polygon edges to form a closed edge polygon.
Click the [Pick] button to select the polylines/polygons from the Map View. After clicking the [Pick] button, the dialog box will temporarily disappear, and a prompt will be displayed on the status bar instructing the user to select polylines/polygons to build. The user can then interactively select polylines/polygons from the Map View.
After selecting the polylines/polygons, press the [Enter] key or right-click and choose Done from the displayed context menu. The number of selected polylines/polygons will be displayed in the Pick polylines/polygons read-only field, as shown below.
The user can click the [Clear] button to cancel the previous selections and redo the entire process.
Map Layer Details
This section allows the user to create a new general drawing layer or a GIS layer for the newly created polygons. By default, the software places the newly created polygons in the Default Drawing Layer. When creating a GIS layer, the polygons are saved as an external shapefile.
The following entries are available in this section:
- Layer type
This dropdown combo box allows the user to select the type of layer to be created for the resulting polygons. The following options are available: - Drawing
This option draws a vector entity of the newly created polygons. This type of layer is similar to the Default Drawing Layer defined in the Map Data Layers panel. By default, this option is selected. - GIS
This option creates a GIS layer as a shapefile for the newly created polygons. The polygon data is stored in an external shapefile.
- Drawing
- Layer name
This dropdown combo box is used to select the layer name that will be displayed in the Map Data Layers panel. Duplicate layer names are not permitted. The user can click the [New] button to define a new layer name.
GIS Layer Details
This section is enabled when the GIS layer type is selected in the Map Layer Details section. Otherwise, this section is disabled (i.e., grayed out).
The Directory entry field defines the path and file name of the shapefile to be created. Click the […] browse button to select the shapefile directory and file name.
The Schema definition table allows the user to define the attribute fields to include in the shapefile layer. The following columns are available in this table:
- Field Name
This column is used to define the field name to be added to the shapefile layer. - Field Type
This column contains a dropdown combo box that is used to select the data type of the field defined above. The following data types are available: - Date
- Floating Point
- Integer
- Integer Array
- Long
- Long Array
- Text
- Text Array
- Width
This spin control column is used to define the maximum character length for a text field. It is enabled only when the Text field type is selected. Otherwise, it is disabled (i.e, grayed out). By default, the software uses a value of 80. However, the user can enter the maximum character length ranging from 1 to 255. Text strings longer than the specified width will be truncated.
Creating Polygons
When all the options have been defined, click the [OK] button. The software will then create new polygons by digitizing the edges of the selected polylines/polygons.