Main Menu - Building Buttons
Build Theme button
The Build Theme button allows you to turn a properly edited line theme into a polygon theme. This function is analogous to ARC/INFO's BUILD function, although it is much slower and not as powerful. You can also incorporate attributes attached to labelpoints into the resulting polygons. The line theme must be topologically 'clean' to be built. As it currently stands, the Build function cannot detect intersect errors; that is, if your lines cross each other, the program will build them anyway and you will not get topologically correct polygons. There is a
line intersection detection function
on the Parcel Editor dialog that you can run to test for these; be aware that it gets exponentially slower the larger your shapefile is.
As experienced GIS users know, polygons have many properties that are essential for display and analysis and the ability to create them from lines is important for data development. The build function works on the first active theme and will test your line theme for certain basic conditions before trying to build it (it can't be editable and can't have any dangles). The build button is located on both the Parcel Editor dialog and the Main Menu dialog.
Unbuild Theme button
The Unbuild Theme button takes a polygon theme and turns it into a line theme and, if you want, a labelpoint theme that can hold the attributes of the polygon theme. Unlike most scripts that do this (and unlike using ARC/INFO's SHAPEARC command on a polygon theme) this does NOT result in lines that overlap or are 'doubled' where polygons abut one another. It produces a topologically 'clean' (assuming your polygons didn't overlap) line theme that can be 'built' back into the same polygon theme in most cases. [Since ArcView, unlike ARC/INFO, supports polygons that can overlap one another, there is no guarantee that you'll have a clean polygon coverage to begin with, and it is very time-consuming to test for this]. This function is useful for editing a polygon theme as lines using the Parcel Editor dialog (which allows for detailed editing and rebuilding), as well as for transferring a theme to ARCINFO.
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