Import GPS coordinates and analyze positional accuracy with North Carolina surveying standards compliance
📋 Instructions & Overview
Purpose: This calculator analyzes GPS measurement precision and accuracy by calculating statistical errors and classifying results according to North Carolina surveying standards (21 NCAC 56 .1603, .1606, .1607).
Key Features:
Statistical Analysis: Calculates RMS, CEP (Circular Error Probable) at 50% and 95% confidence levels
NC Standards Compliance: Automatically classifies results into Class AA, A, B, C, or Fail
Grouping Options:
By name pattern (e.g., cntrl1.1, cntrl1.2)
By distance radius (clusters within specified distance)
Hybrid (name pattern verified by distance)
Vertical Analysis: Optional vertical classification using NC level run standards (requires base point)
How It Works:
Import Data: Upload CSV with point names and coordinates in feet
Accepts N,E,Elev (surveying) format
Accepts X,Y,Z (mathematical) format
Results display in same format as input
Group Points: Automatically detects or manually selects grouping method
Calculate Statistics:
Mean position for each group
Error from mean for each point
RMS and percentile statistics
Classify Results: Project classification based on CEP 95% (not average or worst error)
Important: Project classification is determined by the 95th percentile error (CEP 95%), ensuring that 95% of measurements meet the specified standard. This follows industry best practices and NC surveying regulations.
Statistical Notes:
CEP 95% means 95% of measurements fall within this error threshold
With only 2 points, purple indicates the larger error (statistical percentiles not applicable)
Vertical classification requires distance from reference base per NC standards
NC Standards Quick Reference:
Horizontal (21 NCAC 56 .1603):
• Class AA: ≤0.05 ft + 30ppm (Local Control Network)
• Class A: ≤0.10 ft + 50ppm (Urban Land)
• Class B: ≤0.12 ft + 90ppm (Suburban Land)
• Class C: ≤0.15 ft + 150ppm (Rural/Farmland)
Vertical (21 NCAC 56 .1606):
• Class A: Error ≤ 0.10 × √miles
• Class B: Error ≤ 0.20 × √miles
• Class C: Error ≤ 0.30 × √miles
📁 Import Data File
Upload a CSV file with coordinates in feet
Accepts both surveying (N,E,Elev) and mathematical (X,Y,Z) formats
Compatible with State Plane, UTM, or any projected coordinate system in feet
Results will display in the same format as your input file
Points can be grouped by name pattern (e.g., cntrl1.1, cntrl1.2) or by distance proximity
For NC vertical standards compliance, include your reference base point in the data or specify it below
Sample CSV format (State Plane Coordinates in feet):
Point_Name,N,E,Elev
cntrl1.1,1820220.593,492479.605,817.664
cntrl1.2,1820220.622,492479.597,817.486
cntrl1.3,1820220.583,492479.581,817.551
cntrl2.1,1820334.567,492223.456,813.345
cntrl2.2,1820334.565,492223.458,813.344
Alternative format (for distance-based grouping):
Point_Name,N,E,Elev
P001,1820220.593,492479.605,817.664
P002,1820220.622,492479.597,817.486
P003,1820220.583,492479.581,817.551
P004,1820334.567,492223.456,813.345
P005,1820334.565,492223.458,813.344
BASE1,1820000.000,492000.000,810.000
Legacy format also supported:
Point_Name,X,Y,Z
cntrl1.1,492479.605,1820220.593,817.664
cntrl1.2,492479.597,1820220.622,817.486
Format Requirements:
• Headers can use N,E,Elev (surveying) or X,Y,Z (mathematical) format
• Coordinates must be in feet (State Plane, UTM, or any projected system)
• Point names should follow patterns for automatic grouping (e.g., name.1, name.2)
• Include base point in data if applying vertical standards
Points within this horizontal distance will be grouped together
N:
E:
Elev:
NC vertical standards (21 NCAC 56 .1606) require distance from reference datum for level run classifications
Analysis Results
📊 Data Visualizations
Point Distribution (Plan View)
Click and drag to zoom, double-click to reset
Horizontal Error Distribution
Bars show frequency, curve shows normal distribution