curvature versus slope
  n = 375268 
  X=0, Y = 7.95 +/- 5.92 
  Weighted least-squares fit:  Y = 8.9 + 3.971 X  + -0.05007 X**2 

slope versus dZ, curvature < 5
  n = 230411 
  X=0, Y = 7.76 +/- 5.68 
  Weighted least-squares fit:  Y = 5.6 + 0.195 X  + 0.00240 X**2 
     at X = 100, Y = 49.1 
     effective RMSE xy = 76.6 

slope versus dZ, curvature < 15
  n = 320363 
  X=0, Y = 7.87 +/- 5.62 
  Weighted least-squares fit:  Y = 5.6 + 0.287 X  + 0.00156 X**2 

curvature versus dZ, slope < 10
  n = 286942 
  X=0, Y = 6.56 +/- 4.64 
  Weighted least-squares fit:  Y = 5.3 + 1.792 X  + 0.00069 X**2 


Number of samples 378806
Max dz = 900
Mean dz = 10
RMS dz = 35.2845575288
100cm = 98.9369228576 percentile value of dz