Module 1.2 - Data Quality - Standards

     This week's module involved determining the positional quality of two Albuquerque road networks against the city's aerial imagery. This module follows the procedures outlined by the National Standard for Spatial Data Accuracy (NSSDA). 

 

   The blue road network was sourced from the City of Albuquerque Planning Department, and the red road network was sourced from StreetMap USA. The red points are randomly chosen StreetMap USA intersections. Corresponding intersections in the city's planning dept. dataset and aerial imagery reference were mapped as well.

   In order to determine the horizontal accuracy, I first divided the study area into four quadrants using the Subdivide Polygon tool. This was necessary in order to obtain an ideal distribution of 20 test points as outlined in the 1999 Positional Accuracy Handbook by the Minnesota Planning, Land Management Information Center. After digitizing these points, I used the AddXY Tool to add the X and Y values to the three attribute tables. These tables were then exported using the Table to Excel conversion tool and entered into the Horizontal Positional Accuracy Statistic Worksheet.

     Using the National Standard for Spatial Data Accuracy, the City of Albuquerque Planning Dept. dataset tested 14.2 feet horizontal accuracy at 95% confidence level. Using the National Standard for Spatial Data Accuracy, the StreetMap USA dataset tested 163.8 feet horizontal accuracy at 95% confidence level.