curvature versus slope
  n = 60764 
  X=0, Y = 38.63 +/- 18.30 
  Weighted least-squares fit:  Y = 46.6 + 2.456 X  + -0.02527 X**2 

slope versus dZ, curvature < 5
  n = 23205 

  Weighted least-squares fit:  Y = 19.2 + -0.128 X  + 0.00378 X**2 
     at X = 100, Y = 44.2 
     effective RMSE xy = 62.5 

slope versus dZ, curvature < 15
  n = 38120 

  Weighted least-squares fit:  Y = 19.5 + -0.159 X  + 0.00506 X**2 

curvature versus dZ, slope < 10
  n = 2172 
  X=0, Y = 17.73 +/- 6.64 
  Weighted least-squares fit:  Y = 18.3 + -1.144 X  + 0.49940 X**2 


Number of samples 61435
Max dz = 900
Mean dz = 34
RMS dz = 96.0208310733
100cm = 94.0278342964 percentile value of dz