curvature versus slope
  n = 210680 
  X=0, Y = 11.88 +/- 9.38 
  Weighted least-squares fit:  Y = 19.2 + 4.086 X  + -0.04595 X**2 

slope versus dZ, curvature < 5
  n = 102186 
  X=0, Y = 8.03 +/- 4.72 
  Weighted least-squares fit:  Y = 5.8 + 0.393 X  + -0.00072 X**2 
     at X = 100, Y = 37.9 
     effective RMSE xy = 58.8 

slope versus dZ, curvature < 15
  n = 141324 
  X=0, Y = 8.20 +/- 4.63 
  Weighted least-squares fit:  Y = 5.8 + 0.438 X  + -0.00068 X**2 

curvature versus dZ, slope < 10
  n = 94391 
  X=0, Y = 7.74 +/- 4.67 
  Weighted least-squares fit:  Y = 7.3 + 1.052 X  + 0.09200 X**2 


Number of samples 212480
Max dz = 900
Mean dz = 19
RMS dz = 50.6557005677
100cm = 97.2693900602 percentile value of dz