curvature versus slope
  n = 656718 
  X=0, Y = 17.15 +/- 15.00 
  Weighted least-squares fit:  Y = 31.4 + 3.720 X  + -0.04209 X**2 

slope versus dZ, curvature < 5
  n = 348043 
  X=0, Y = 17.74 +/- 6.48 
  Weighted least-squares fit:  Y = 12.2 + 0.066 X  + 0.00187 X**2 
     at X = 100, Y = 37.6 
     effective RMSE xy = 55.8 

slope versus dZ, curvature < 15
  n = 407524 
  X=0, Y = 17.59 +/- 6.57 
  Weighted least-squares fit:  Y = 11.8 + 0.214 X  + 0.00245 X**2 

curvature versus dZ, slope < 10
  n = 269523 
  X=0, Y = 12.19 +/- 7.61 
  Weighted least-squares fit:  Y = 10.6 + 3.040 X  + -0.02960 X**2 


Number of samples 665305
Max dz = 900
Mean dz = 36
RMS dz = 69.6275807421
100cm = 89.2501935203 percentile value of dz