curvature versus slope
  n = 645697 
  X=0, Y = 10.76 +/- 8.97 
  Weighted least-squares fit:  Y = 13.1 + 4.845 X  + -0.05791 X**2 

slope versus dZ, curvature < 5
  n = 359584 
  X=0, Y = 8.51 +/- 4.42 
  Weighted least-squares fit:  Y = 8.8 + 0.204 X  + 0.00230 X**2 
     at X = 100, Y = 52.2 
     effective RMSE xy = 80.8 

slope versus dZ, curvature < 15
  n = 520323 
  X=0, Y = 8.71 +/- 4.74 
  Weighted least-squares fit:  Y = 9.1 + 0.270 X  + 0.00137 X**2 

curvature versus dZ, slope < 10
  n = 368892 
  X=0, Y = 9.38 +/- 5.01 
  Weighted least-squares fit:  Y = 8.7 + 1.821 X  + 0.04460 X**2 


Number of samples 654633
Max dz = 900
Mean dz = 15
RMS dz = 30.3150127824
100cm = 98.5005338869 percentile value of dz