curvature versus slope
  n = 1269106 
  X=0, Y = 47.55 +/- 26.57 
  Weighted least-squares fit:  Y = 63.3 + 1.555 X  + -0.01624 X**2 

slope versus dZ, curvature < 5
  n = 36111 

  Weighted least-squares fit:  Y = 17.4 + 0.617 X  + -0.00212 X**2 
     at X = 100, Y = 57.8 
     effective RMSE xy = 86.6 

slope versus dZ, curvature < 15
  n = 172701 

  Weighted least-squares fit:  Y = 25.5 + 0.454 X  + -0.00097 X**2 

curvature versus dZ, slope < 10
  n = 3322 
  X=0, Y = 18.89 +/- 10.97 
  Weighted least-squares fit:  Y = 27.7 + -1.892 X  + 0.15603 X**2 


Number of samples 1285397
Max dz = 900
Mean dz = 60
RMS dz = 83.0421579681
100cm = 82.9775547944 percentile value of dz