The Build Polygons command allows the user to create polygons from the existing polylines. For example, the user might want to digitize a complex watershed boundary in stages, in order to break down the work into manageable tasks.
Note that the polylines must connect with each other where no breaks are allowed between the polyline connections.
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 the Build Polygons command and how to interact with the above dialog box.
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 on what to do next. The user can then interactively select polylines/polygons from the Map View.
After selecting the polylines/polygons, the number of selected polylines/polygons will be displayed in the Pick polylines/polygons read-only field. Click the [Clear] button to cancel all the previous selections and redo the entire process.
Note that if the polylines/polygons were pre-selected prior to running this command, then the Pick polylines/polygons read-only field will display the number of selected polylines/polygons.
Map Layer Details
This section allows the user to create a new general drawing layer or a GIS layer for the 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 a shapefile.
The following entries are provided in this section to define the type and name of the map layer:
- Layer type
This dropdown combo box defines the type of layers that can be created. The following options are provided:
This option is used to draw a vector entity of the newly created polygons. This type of layer is identical to the Default Drawing Layer that is defined in the Map Data Layers panel. By default, this option is selected.
This option is used to create a GIS layer for creating a shapefile of the newly created polygons. This data is stored within an external shapefile.
- Layer name
This field defines 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 gets enabled when the user selects a GIS layer type. Otherwise, the options in this section are not available.
The Directory field defines the path and name of the shapefile to be created. Click the […] browse button to select the shapefile directory and file name.
The Schema definition data table allows the user to define the fields to include for the shapefile layer.
This data table requires the following data:
- Field Name
This data column is used to define the field name to add to the shapefile layer.
- Field Type
This dropdown combo box is used to select the data type of the field defined above. The following data types are provided:
- Floating Point
This spin control button is only available for text field types and has a default value of 80. This spin control can range from 1 to 255. The strings longer than the field width that do not fit into the field format will be truncated.
When all the data have been defined in the dialog box, click the [OK] button and the software will create new polygons by digitizing the edges of the selected polylines/polygons.
Note that if the selected polylines are disjointed/not connected, then the following informational message will be displayed.