Special Topics: Lab 2

Lab 2 covered the National Standard for Spatial Data Accuracy.  The lab looked at junction points for two data sets.  To perform this lab, I needed to create two new Data set Networks for the street shapefiles.  I selected over 85 points of the junction shapefile for the city and over 85 for the USA street shapefile.

After selecting the points, I exported the points into new shapefiles.  I then added orthophotos to see where the true intersections are located.  Zooming into each pair a test points, I found the true location and added a reference point.  I did that for all points.  A unique identifier was applied to all three data sets.  I used the Add X Y Coordinates to the attribute tables.

I exported the attribute tables for the three shape files and inserted the data into the Horizontal Accuracy spreadsheet.  This spreadsheet found the difference between the X and Y coordinates.  The differences were squared and summed.  The Root Square Mean Error was also calculated and multiplied by 1.7308 for the standard error.  This was done for the city data points and the street data points.

City:
Positional Accuracy: Using the National Standard for Spatial Data Accuracy, tested 30.64 feet horizontal accuracy at 95% confidence level.
USA Street:
Positional Accuracy: Using the National Standard for Spatial Data Accuracy, test 62.67 feet horizontal accuracy at 95% confidence level.

Test Points