curvature versus slope
  n = 929766 
  X=0, Y = 10.20 +/- 6.96 
  Weighted least-squares fit:  Y = 9.3 + 3.839 X  + -0.04392 X**2 

slope versus dZ, curvature < 5
  n = 369304 
  X=0, Y = 5.66 +/- 5.71 
  Weighted least-squares fit:  Y = 9.5 + 0.615 X  + -0.00400 X**2 
     at X = 100, Y = 30.9 
     effective RMSE xy = 46.3 

slope versus dZ, curvature < 15
  n = 723006 
  X=0, Y = 5.90 +/- 5.91 
  Weighted least-squares fit:  Y = 11.6 + 0.448 X  + -0.00033 X**2 

curvature versus dZ, slope < 10
  n = 445990 
  X=0, Y = 12.21 +/- 8.52 
  Weighted least-squares fit:  Y = 11.4 + 2.312 X  + 0.04416 X**2 


Number of samples 934258
Max dz = 700
Mean dz = 16
RMS dz = 24.2280828792
100cm = 99.4350596944 percentile value of dz