For this lab we looked at the city streets of Albuquerque, New Mexico. The image above is a screenshot of the test points selected for the accuracy analysis. To obtain the accuracy statistics for the layer we had to create a network data set for intersection points within the street layer. Once the points were created a random generator was used to select a number of random points throughout the study area. The selected points were then narrowed down based on the criteria for an appropriate test point. Finally twenty-four points remained. Next the points were compared to more accurate orthophotos. Reference points were placed on the correct or "true" location that the selected points were trying to represent. The distance between these points was used to then calculate the accuracy statistics based on the NSSDA guidelines. The accuracy statement derived for the above layer is:
Horizontal Positional Accuracy:
Tested 243.08 feet horizontal accuracy at 95% confidence level
The depicted layer was found to be the lesser accurate of the two layers tested and did not represent the true locations as well as the other layer.
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