curvature versus slope
  n = 57648 
  X=0, Y = 38.80 +/- 25.23 
  Weighted least-squares fit:  Y = 67.9 + 1.363 X  + -0.01458 X**2 

slope versus dZ, curvature < 5
  n = 3574 

  Weighted least-squares fit:  Y = 20.5 + -0.473 X  + 0.00925 X**2 
     at X = 100, Y = 65.7 
     effective RMSE xy = 98.1 

slope versus dZ, curvature < 15
  n = 8042 

  Weighted least-squares fit:  Y = 19.2 + -0.335 X  + 0.01013 X**2 

curvature versus dZ, slope < 10
  n = 866 
  X=0, Y = 17.00 +/- 6.50 
  Weighted least-squares fit:  Y = 18.2 + -0.800 X  + 0.19593 X**2 


Number of samples 58233
Max dz = 900
Mean dz = 89
RMS dz = 142.663940784
100cm = 67.7966101695 percentile value of dz