curvature versus slope
  n = 296904 
  X=0, Y = 44.95 +/- 32.03 
  Weighted least-squares fit:  Y = 71.4 + 1.232 X  + -0.01303 X**2 

slope versus dZ, curvature < 5
  n = 10484 

  Weighted least-squares fit:  Y = 13.5 + 0.848 X  + -0.00127 X**2 
     at X = 100, Y = 85.6 
     effective RMSE xy = 132.8 

slope versus dZ, curvature < 15
  n = 33919 

  Weighted least-squares fit:  Y = 14.7 + 0.952 X  + -0.00199 X**2 

curvature versus dZ, slope < 10
  n = 1601 
  X=0, Y = 17.29 +/- 8.46 
  Weighted least-squares fit:  Y = 16.2 + 3.677 X  + -0.14017 X**2 


Number of samples 300792
Max dz = 900
Mean dz = 87
RMS dz = 125.502988012
100cm = 67.7069203968 percentile value of dz