curvature versus slope
  n = 364784 
  X=0, Y = 14.44 +/- 12.39 
  Weighted least-squares fit:  Y = 20.4 + 4.278 X  + -0.04984 X**2 

slope versus dZ, curvature < 5
  n = 185829 
  X=0, Y = 4.48 +/- 4.35 
  Weighted least-squares fit:  Y = 4.5 + 0.330 X  + 0.00115 X**2 
     at X = 100, Y = 49.0 
     effective RMSE xy = 76.7 

slope versus dZ, curvature < 15
  n = 262860 
  X=0, Y = 4.71 +/- 4.41 
  Weighted least-squares fit:  Y = 4.7 + 0.351 X  + 0.00111 X**2 

curvature versus dZ, slope < 10
  n = 169696 
  X=0, Y = 6.08 +/- 4.33 
  Weighted least-squares fit:  Y = 5.6 + 1.165 X  + 0.10147 X**2 


Number of samples 369548
Max dz = 900
Mean dz = 15
RMS dz = 40.7062648741
100cm = 97.9109614989 percentile value of dz