DeLorme Professional Weblog

What is the function of the Magic Wand Selection tool in the XMap toolbar? It is always grayed out, even after I make a layer active.

The Magic Wand Selection tool was added to XMap for some very specific applications and it requires that several prerequisites are satisfied before it becomes available. 

The object of the tool is to allow the concurrent selection of multiple line segments that are connected and share a common attribute. This provides the means to verify that the particular attribute has been consistently assigned for each selected segment and to ensure that the line segments are actually connected without any breaks. It also simplifies the process of editing attributes as all sections of the line can be updated simultaneously.

The Magic Wand Tool is essential for DeLorme’s corporate road and street data management process. Technicians are able to quickly ascertain whether roads, which are typically represented in the database by many individual line segments, are connected and that each segment has the correct road label. DeLorme software depends on this verification of connectivity and label consistency to ensure that the route planning tool provides the optimal directions and to guarantee that address searches return accurate results.

While not every XMap user will find a need for the Magic Wand Selection function, several innovative applications have recently been brought to our attention. These include an energy company using the tool to manage gas pipeline maintenance schedules, and a public works department monitoring water supply lines.

In order to perform a Magic Wand Selection, the geometry shape of the line layer must be changed to topological using the Layer Properties dialog box. This exposes the nodes that represent the connectivity relationship between intersecting and adjacent line segments. A User Input query must then be created based on the attribute which is common to each segment. After these modifications have been made and the layer is made active in the drop down list in the toolbar, the Magic Wand Selection tool will be available.

The following procedure is an example of the practical use of the Magic Wand Selection tool in XMap using a layer containing bus routes served by the Washington DC Metropolitan Transit Authority. In this case, the Magic Wand tool will allow us to quickly see the roads and streets served by each numbered route. To follow along with these steps, download the shapefile named Metro Bus Routes from the DC GIS Data Clearinghouse at http://dcatlas.dcgis.dc.gov/catalog.

1. After importing the metro bus routes shapefile, use the Symbolize tool to select your preferred color and style for the lines. In this case a layer classification is not necessary.
2. Right-click on the layer in the workspace and choose Properties.
3. From the Geometry Shape drop down list, choose Topological Geometry and uncheck the boxes next to Shape Points and End Nodes. This setting will disable or turn off all of the nodes, which are not needed for this application, thus ensuring that the map is uncluttered.
4. Click the Query button on the left of the tab area and ensure that the Metro Bus Routes layer is selected in the Layer drop down list.
5. Build a query using the following parameters:
   • Attribute – LINENAME
   • Operator – EQUALS
   • Criteria – [Leave Blank]
   • Logical Operator – [Leave Blank]
   • User Input – Check Box
6. Give the query a name, such as “Search by Route”, by clicking the Manage button and selecting Rename.
7. In the toolbar above the map window, select Metro Bus Routes from the Active Layer drop down list.
8. Click the arrow on the Magic Wand Selection button and select the query that was just created
9. Use the tool to select a line segment on the map. The entire route will be highlighted, indicating the directions followed by that particular bus route. Furthermore the attributes for this route will be highlighted below the map. To filter this list so that only the results of the Magic Wand Selection are displayed, choose Toolbar Select from the Show drop down list above the attributes table.

The Magic Wand Selection tool is further example of DeLorme’s commitment to developing innovative and practical spatial technology that is accessible to all.