curvature versus slope
  n = 421227 
  X=0, Y = 9.81 +/- 7.29 
  Weighted least-squares fit:  Y = 14.0 + 4.304 X  + -0.04693 X**2 

slope versus dZ, curvature < 5
  n = 242632 
  X=0, Y = 5.69 +/- 3.72 
  Weighted least-squares fit:  Y = 3.7 + 0.402 X  + 0.00043 X**2 
     at X = 100, Y = 48.3 
     effective RMSE xy = 75.6 

slope versus dZ, curvature < 15
  n = 331585 
  X=0, Y = 5.93 +/- 3.78 
  Weighted least-squares fit:  Y = 4.2 + 0.417 X  + 0.00047 X**2 

curvature versus dZ, slope < 10
  n = 262478 
  X=0, Y = 5.48 +/- 3.54 
  Weighted least-squares fit:  Y = 5.1 + 1.257 X  + 0.10113 X**2 


Number of samples 428129
Max dz = 900
Mean dz = 15
RMS dz = 41.7731971484
100cm = 97.3143608585 percentile value of dz