curvature versus slope
  n = 219227 
  X=0, Y = 31.07 +/- 29.63 
  Weighted least-squares fit:  Y = 65.6 + 1.300 X  + -0.01312 X**2 

slope versus dZ, curvature < 5
  n = 8533 

  Weighted least-squares fit:  Y = 2.0 + 0.616 X  + -0.00086 X**2 
     at X = 100, Y = 55.0 
     effective RMSE xy = 86.3 

slope versus dZ, curvature < 15
  n = 24643 

  Weighted least-squares fit:  Y = 3.3 + 0.675 X  + -0.00123 X**2 

curvature versus dZ, slope < 10
  n = 6442 
  X=0, Y = 4.22 +/- 3.29 
  Weighted least-squares fit:  Y = 3.5 + 3.469 X  + -0.03768 X**2 


Number of samples 224158
Max dz = 900
Mean dz = 59
RMS dz = 94.1116358374
100cm = 82.3999143461 percentile value of dz