Appearance of an area feature with inner boundaries is often connected with creation of a new feature lying inside the existing one but belonging to a different type. For example, if a house is built inside a garden, the house boundary becomes inner boundary of the garden. To provide precise coincidence of these two boundaries it is desirable to have a possibility to create one of them on the basis of another boundary using a special operation, not manually.
ObjectLand provides a possibility to create a new area feature based on the inner boundary of another one (if we take the same example of a garden, at first an area in the garden was fenced off and then the house was built) and also with a possibility of reverse operation – adding inner boundary of an area feature based on the outer boundary of another area feature (at first the house was built, then the territory of the house was excluded from the garden).
Transformation of a feature to inner boundary of another feature and back is shown at figure 18-7.
Figure 18-7. Transformation of a feature to inner boundary
To create an area feature based on one of inner boundaries of another area feature the user should perform the following sequence of operations:
Switch to the mode Edit, submode Editing vertices and select one of the vertices of the inner boundary being transformed.
Call the context menu and perform the command Transform, select direction for transformation: Inner Boundary to Feature in the nested menu. A dialog box shown at figure 18-8 will be opened.
Figure 18-8. Dialog box “Transforming the inner boundary to area feature”
Determine if the inner boundary basing on which the feature was created should be removed simultaneously with creation of new feature (checkbox Remove inner boundary) or it should be retained.
After pushing the button Perform a new area feature of the same type to which the original feature with inner boundary belongs will be created.
For performing reverse transformation, that is, adding an inner boundary of one (“outer”) area feature based on the outer boundary of another (“inner”) feature the following actions should be made:
Switch to the mode Edit and select “inner” feature for editing.
Call context menu and perform the command Transform. Select direction of the transformation: Feature to Inner Boundary from the nested menu.
To select the “outer” feature for transformation click this feature. A dialog box shown at figure 18-9 will be opened.
Figure 18-9. “Transforming the area feature to inner boundary”
Determine if “inner” feature should be removed simultaneously with creation of inner boundary of “outer” feature (checkbox Remove feature), or it should be retained.
If the status “The operation is possible” is indicated in the dialog box, after pushing the button Perform new inner boundary of ”outer” feature coinciding with outer boundary of “inner” feature will be added.
If “inner” feature has inner boundaries itself, they are ignored when the operation is performed.
The operation cannot be performed in the case when some parts of “inner” feature lie outside the “outer” one.
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