curvature versus slope
  n = 611299 
  X=0, Y = 40.65 +/- 30.57 
  Weighted least-squares fit:  Y = 77.0 + 1.047 X  + -0.01028 X**2 

slope versus dZ, curvature < 5
  n = 3523 

  Weighted least-squares fit:  Y = 66.4 + -0.470 X  + 0.00494 X**2 
     at X = 100, Y = 68.8 
     effective RMSE xy = 28.3 

slope versus dZ, curvature < 15
  n = 19238 

  Weighted least-squares fit:  Y = 61.3 + -0.048 X  + 0.00294 X**2 

curvature versus dZ, slope < 10
  n = 982 
  X=0, Y = 62.56 +/- 24.22 
  Weighted least-squares fit:  Y = 66.9 + -4.120 X  + 0.24454 X**2 


Number of samples 616634
Max dz = 900
Mean dz = 91
RMS dz = 119.331471121
100cm = 63.2172406971 percentile value of dz