curvature versus slope
  n = 57918 
  X=0, Y = 45.25 +/- 35.63 
  Weighted least-squares fit:  Y = 67.9 + 1.080 X  + -0.01014 X**2 

slope versus dZ, curvature < 5
  n = 1661 

  Weighted least-squares fit:  Y = 7.4 + 0.456 X  + -0.00033 X**2 
     at X = 100, Y = 49.8 
     effective RMSE xy = 77.3 

slope versus dZ, curvature < 15
  n = 5224 

  Weighted least-squares fit:  Y = 8.7 + 0.480 X  + -0.00045 X**2 

curvature versus dZ, slope < 10
  n = 890 
  X=0, Y = 10.92 +/- 6.13 
  Weighted least-squares fit:  Y = 10.4 + 1.069 X  + 0.12312 X**2 


Number of samples 58200
Max dz = 900
Mean dz = 57
RMS dz = 120.84701072
100cm = 86.0687285223 percentile value of dz