curvature versus slope
  n = 951976 
  X=0, Y = 83.51 +/- 21.31 
  Weighted least-squares fit:  Y = 84.3 + 0.560 X  + -0.00433 X**2 

slope versus dZ, curvature < 5
  n = 2155 

  Weighted least-squares fit:  Y = 7.7 + 0.153 X  + 0.00071 X**2 
     at X = 100, Y = 30.1 
     effective RMSE xy = 45.7 

slope versus dZ, curvature < 15
  n = 22487 

  Weighted least-squares fit:  Y = 12.2 + 0.198 X  + 0.00042 X**2 

curvature versus dZ, slope < 10
  n = 44 

  Weighted least-squares fit:  Y = 13.8 + -5.376 X  + 1.41245 X**2 


Number of samples 964866
Max dz = 900
Mean dz = 57
RMS dz = 80.8517161228
100cm = 82.8034151893 percentile value of dz