Digitizing using Clean and Build

You can digitize polygons using the standard Digitize tool. But, consider the following: If the polygons do not share a common border, you would draw them as you would polylines. But where they share a common border you would draw with various snapping options on. However, even with snapping, it can be tedious. You have to digitize around both borders, and if you miss a snap, you may end up with gaps or overlaps. This idea is to digitize polylines instead and then clean and build polygons.

The advantages are:

You only cover the same territory once you can reposition (edit) nodes without concern about making both borders fit it is easier to see what you have on screen when you pan and zoom the amount of time you spend on the project is greatly reduced The trick is not to leave gaps or to run over the same area. You set snapping on and digitize polylines into a polyline file, making sure that where there is no snap point that you cross the line with another or use the EV8 boundary snap. This is a purposeful creation of dangles.

You get something like this;

You then run any of the EV8 clean and build tools to get your polygons. Do not set a tolerance. Dangles are ignored by EV8 polygon build. The polygons will all have perfectly matching borders, and will not have slivers, gaps, or overlaps. Common intersections are not shifted by a 'fuzzy' tolerance.

If you look at the polyline sketch above, you will see that the work is easily divided into subsets. The way to do this is to draw a set of general borders first, trying to break the task into natural sections. Then as shown in the upper left part of the sketch, you work within each subset. Data created within the boundaries of a subset can be save in different files, or done by different people, and merged later.

Note: Dangles are not ignored by EV8 polyline build.


Attributes can be added using the Attribute Read/Edit tool. You could use the Write Attributes File-to-File function if you have the attributes in some other form. For example, a GPS point file may contain a connection to a database of some sort, or a CAD may contain a text layer. Any file that can be read into ArcMap, and made into a shapefile can be used with this function to automatically write both the fields and the data via a spatial pattern you choose when running the function. So before you start a manual attribute session adding look around to see if the data is stored elsewhere.