Issue 66

Analyze Map Boundary Data Using the Query Command in MapViewer 7

When working with digital maps, you may need to select map boundaries that meet specific criteria, such as a polygon that defines a county, whose population is less than 500,000. Rather than tirelessly searching through the worksheet, you can use MapViewer’s Query command to spatially analyze your map boundary data. When using a query string in MapViewer, you have the freedom to select the object data, object attribute, operator, and an optional function. This article will demonstrate how easy it is to select specific map data when using the Query command in MapViewer.

Using a Query String in MapViewer

To spatially analyze your data using a query string in MapViewer, you will first need a digital map project that contains map boundary data and associated object attributes. Click here to download a MapViewer project file that contains digitized line and point boundaries with associated attributes that we can use to query. We will use the Query command in MapViewer to identify a paved bike friendly road that crosses a mountain pass.

The image above is a section from the Colorado Bicycling and Scenic Byways Map provided by the Colorado Department of Transportation.

1. Click File | Open and in the Open dialog, select the GSM file, and click Open. A map projected is displayed.
2. Scroll through the Object Manager and notice there is a host of point and curve objects with varying attributes.
3. To show curves that meets a specific criteria click Analysis | Query. Our first goal is to select a route that would be road bicycle friendly.
4. In the Query dialog set up your query string to: Select Curves in the Map where Attrib1 = “Bikes” and Attrib2 = “Paved”, so that your Query dialog matches mine, and then select OK.
   



You can quickly select all curves that meet the criteria of being
both bicycle friendly and paved using a query string in MapViewer.

5. Now that we have selected curves that meet our road biking criteria, let’s change the line properties so that we can easily identify potential routes. In the Property Inspector within the Line Properties section change the Style to Solid, Color to Orange, and the Width to 0.050 in.



Edit your curve properties to identify a route that meets your specified criteria.

6. We can further query the map to identify curves that are not only bicycle friendly and paved, but also cross a mountain pass. Click Analysis | Query and in the Query dialog set up your querry string to: Select Points in the Map where the SID = “Mtn Pass”. Ensure that your Query dialog matches mine, and then select OK.
   



Use the MapViewer Query string to identify points that meet your criteria.

7. Let’s change the symbol properties to make all the mountain passes easier to identify. In the Property Inspector within the Symbol Properties change Symbol to the 15 the filled triangle and the color to Red and the symbol size to 0.20 in.
8. Our results identify two routes that meet all our specified criteria, a paved, bike friendly road that crosses a mountain pass.



Quickly and efficiently analyze your map data using MapViewer's Query command

Using MapViewer’s Query command allows for fast and easy spatial analysis. The query string allows you to quickly and confidently select all map data that meets your specific criteria.