Special Topics Module 1.2 Lab 2

 

Special Topics

Module 1.2 Lab 2

For this lab, we were given vectorized data in the form of a few polyline and polygon feature classes to determine the amount of error that exists between two data sets of roads for a city. 

The process consists of: 

1. Establishing a new point file called "reference points". 

    In this step I created a new point feature-class and chose 20 locations within the study area creating a point for each location. The placement of the location for each point represents the "true intersection" of a road. 

2. Created two new point feature classes, one for each of the streets. 

    In this step, I worked on one point feature class at a time and created a point on each line vertices of the targeted road line feature class corresponds to the nearest reference point. I made sure to follow the same path that I took when making the reference points and even labeled the reference points so that I didn't go out of order. After which I  created points for the other 19 reference locations. I then repeated this step for the second point feature class. 

Below is a image of what the 20 reference points within the study area. 

 

3. Added X, Y to each of the three tables. 

4. Performed a table join to each of the road point layers. 

5. I created two new fields in each of the road point layer tables called "Ref_x" and "Ref_Y"

    This prepares the table for the field calculate tool. 

6. I then ran calculate field in the joined table and added the reference x,y coordinates to both road point tables. 

Now that the data I need to begin the error analysis is in both tables, I exported them to excel. 

Within excel, I then began calculating the sum, mean, median, RMSE, and 95th percentile of error. 

I then created a NSSDA statement of the determined error.