curvature versus slope
  n = 627677 
  X=0, Y = 10.32 +/- 8.85 
  Weighted least-squares fit:  Y = 18.7 + 4.376 X  + -0.05125 X**2 

slope versus dZ, curvature < 5
  n = 332245 
  X=0, Y = 8.59 +/- 6.47 
  Weighted least-squares fit:  Y = 8.8 + 0.196 X  + 0.00217 X**2 
     at X = 100, Y = 50.1 
     effective RMSE xy = 77.5 

slope versus dZ, curvature < 15
  n = 462148 
  X=0, Y = 9.18 +/- 6.92 
  Weighted least-squares fit:  Y = 9.0 + 0.232 X  + 0.00201 X**2 

curvature versus dZ, slope < 10
  n = 350633 
  X=0, Y = 9.38 +/- 6.53 
  Weighted least-squares fit:  Y = 8.5 + 1.795 X  + 0.00153 X**2 


Number of samples 640138
Max dz = 900
Mean dz = 20
RMS dz = 44.9221548904
100cm = 96.3503182126 percentile value of dz