curvature versus slope
  n = 202682 
  X=0, Y = 9.24 +/- 7.49 
  Weighted least-squares fit:  Y = 19.1 + 3.971 X  + -0.04413 X**2 

slope versus dZ, curvature < 5
  n = 97217 
  X=0, Y = 14.04 +/- 5.72 
  Weighted least-squares fit:  Y = 15.7 + 0.001 X  + 0.00251 X**2 
     at X = 100, Y = 41.0 
     effective RMSE xy = 59.4 

slope versus dZ, curvature < 15
  n = 122042 
  X=0, Y = 14.63 +/- 5.81 
  Weighted least-squares fit:  Y = 15.2 + 0.117 X  + 0.00201 X**2 

curvature versus dZ, slope < 10
  n = 100284 
  X=0, Y = 15.69 +/- 6.67 
  Weighted least-squares fit:  Y = 15.6 + 0.404 X  + 0.10617 X**2 


Number of samples 203899
Max dz = 900
Mean dz = 31
RMS dz = 73.5798885566
100cm = 94.2191967592 percentile value of dz