curvature versus slope
  n = 185892 
  X=0, Y = 20.31 +/- 17.73 
  Weighted least-squares fit:  Y = 49.5 + 2.314 X  + -0.02557 X**2 

slope versus dZ, curvature < 5
  n = 30325 
  X=0, Y = 3.09 +/- 2.19 
  Weighted least-squares fit:  Y = 4.9 + 0.435 X  + -0.00001 X**2 
     at X = 100, Y = 48.3 
     effective RMSE xy = 75.4 

slope versus dZ, curvature < 15
  n = 50117 
  X=0, Y = 3.09 +/- 2.19 
  Weighted least-squares fit:  Y = 4.8 + 0.515 X  + -0.00049 X**2 

curvature versus dZ, slope < 10
  n = 21604 
  X=0, Y = 7.31 +/- 5.29 
  Weighted least-squares fit:  Y = 6.2 + 2.095 X  + 0.01455 X**2 


Number of samples 187679
Max dz = 900
Mean dz = 45
RMS dz = 78.9683480896
100cm = 87.7668785533 percentile value of dz