Function Description

In an editable state, use the drawn polyline to update parts of line objects or polygon objects. The local update function can use the intersecting part of this polyline with the source object (the line object to be updated) to form a new object.

• The local update function is applicable to line layers, polygon layers, and CAD layers.
• When no object to be updated is selected, the start and end points of the drawn polyline must be on the boundary of the object to be updated. Therefore, it is recommended to turn on the snapping function during operation.
• If the object to be updated is selected, the clip mode can be used for update. The drawn polyline needs to have at least two intersection points with the object to be updated.
• Objects participating in local update can be simple objects or single sub-objects of complex objects, but cannot be compounds.
• In the local update operation, depending on the object type to be updated, the update results will differ. The following will detail the update of line objects and polygon objects.
  • When the object to be updated is an unselected line object (snapping mode)

    As shown in the figure below, it is a schematic diagram of local update for an unclosed and unselected line object.

    Figure 1 shows the line object to be updated. It is updated using the polyline drawn in Figure 2. The start and end points of the polyline must be on the line object. The highlighted and bold line segment in Figure 2 is the result of local update.

    The drawn update line segment divides the line object to be updated into three segments. After determining the start and end points of the update polyline, if you press the keyboard shortcut Ctrl or Shift, you can switch the local update result, as shown in the highlighted and bold line segment in Figure 3.

    Figure 1: Object to be updated	Figure 2: Local update operation	Figure 3: Switching local update result

  • When the object to be updated is a selected line object (clip mode)

    As shown in the figure below, it is a schematic diagram of local update for an unclosed and selected line object.

    Figure 4 shows the line object to be updated. It is updated using the polyline drawn in Figure 5. The drawn polyline needs to have two or more intersection points with the line object to be updated. The highlighted and bold line segment in Figure 5 is the result of local update.

    The drawn update line segment divides the line object to be updated into three segments. After determining the start and end points of the update polyline, if you press the keyboard shortcut Ctrl or Shift, you can switch the local update result, as shown in the highlighted and bold line segment in Figure 6.

    Figure 4: Object to be updated	Figure 5: Local update operation	Figure 6: Switching local update result

  • When the object to be updated is an unselected polygon object (snapping mode)

    As shown in the figure below, it is a schematic diagram of local update for a closed and unselected polygon object.

    Ensure that the start and end points of the update polyline are on the boundary line of the polygon object. The preview effect of the update results is a blue area (Figure 8), and the boundary line of the updated polygon object is highlighted and bold. If you press the Ctrl or Shift key, the update results will automatically switch, as shown in the blue area between the highlighted and bold line segments in Figure 9.

    Figure 7: Closed polygon object to be updated	Figure 8: Local update result 1	Figure 9: Local update result 2

  • When the object to be updated is a selected object (clip mode)

    As shown in the figure below, it is a schematic diagram of local update for a closed and selected polygon object.

    The start and end points of the update polyline can be inside or outside the boundary line of the polygon object. The drawn polyline needs to have two or more intersection points with the boundary line of the polygon object. The preview effect of the update results is a blue area (Figure 11), and the boundary line of the updated polygon object is highlighted and bold. If you press the Ctrl or Shift key, the update results will automatically switch, as shown in the blue area between the highlighted and bold line segments in Figure 12.

    Figure 10: Closed polygon object to be updated	Figure 11: Local update result 1	Figure 12: Local update result 2

Function Entry

• Edit Data tab -> Feature Editing group -> General editing -> Trimming -> Local update

Operation Instructions

1. In the Layer Manager, set the layer to an editable state.
2. In the Edit Data tab, in the General editing drop-down menu, click the Local update button in the Trimming group to perform the local update operation. At this time, a polyline cursor will appear in the map.
3. Local update has two operation modes: snapping mode and clip mode. The operation method differs depending on whether the object to be updated is selected. If no object to be updated is selected, only the snapping mode can be used for update. If the object to be updated is selected, either snapping mode or clip mode can be used for update.
   • Snapping mode: Move the polyline cursor to the boundary of the line object or polygon object to be updated. The start and end points of the drawing must be on the boundary of the object to be updated. If not on its boundary, the output window will prompt: "the point should be in the line when updating with capture mode. please select an object if you want to update with clip mode." You need to redraw the start point. If the start point of the drawn polyline snaps to the line, it must be in snapping mode.
     Note:

     To use snapping mode, you need to first enable the Point Snapping to Lines function in Snapping Settings.

   • Clip mode: Select the object to be updated. The start point of the drawing can be on or off the boundary of the object to be updated, but the drawn polyline needs to have two or more intersection points with the boundary line of the line object or polygon object.
4. Continue drawing the polyline. When the drawn point snaps to the object to be updated, the updated shape will be automatically highlighted. The currently drawn polyline will divide the boundary of the object to be updated into multiple segments. Hold down the Ctrl key to switch and select the boundary to update.
5. Click the right mouse button to confirm using the currently drawn shape for update, completing the local update operation.