Among the exciting new GIS components developed for XMap 7 is an ingenious tool for streamlining the process of creating or modifying polygons. The Edge Matching tool, as its name implies, provides an efficient and effective way to automatically match the edge of a polygon with the corresponding edge of its neighbor. In short, this tool saves a lot of duplicated effort when creating adjacent irregular polygons.
To help provide an appreciation of the value of this tool and to describe how it works in a practical sense, we will consider a common application for manual polygon creation: parcel mapping.
If you are lucky enough to play your GIS trade in the vast central section of the United States, property mapping is a relative breeze. Thanks to the Jeffersonian survey system, properties are typically regular, four-sided polygons, stretching as far as the eye can see. Click, click, click, click and you’re ready for the next one. Here in New England, property boundaries tend to be based not on a universal consistent system but on local geographic or hydrographic features such as streams or ridgelines, which do not usually follow straight lines or intersect at right angles.
When mapping adjoining parcels of this type, it is unavoidable that each boundary line must be precisely duplicated to avoid any holes or overlap. This process usually doubles the time and effort needed to create the parcel database—it was for such situations that XMap’s Edge Matching feature was developed.
To use the Edge Matching tool in either the Editor or Enterprise version of XMap, follow these steps.
- Create or import the first polygon, making sure it is accurately delineated.
- Create a simple version of the adjacent polygon (four points is sufficient).
- Click the Edge Matching tool on XMap’s toolbar and click anywhere within the simple polygon.
- Select the two shape points at either end of the section of this polygon that will be matched. These anchor points will be symbolized with pink boxes.
- Click anywhere within the first polygon and repeat the anchor point selection process for the two points that correspond with ends of the section of the boundary to be matched. A dashed line on the map provides a visual indication as to which of the two previously selected points will be matched. After the second point is selected, the corresponding edge of new polygon will be automatically redrawn and matched to the shape of the original polygon.
The Edge Matching tool not only saves time and effort in polygon mapping projects, it also ensures accuracy in the mapping process by eliminating the likelihood of mismatched or omitted points.
