curvature versus slope
  n = 1136253 
  X=0, Y = 19.14 +/- 15.38 
  Weighted least-squares fit:  Y = 43.9 + 2.610 X  + -0.02754 X**2 

slope versus dZ, curvature < 5
  n = 69726 

  Weighted least-squares fit:  Y = 5.3 + 0.176 X  + 0.00070 X**2 
     at X = 100, Y = 30.0 
     effective RMSE xy = 46.3 

slope versus dZ, curvature < 15
  n = 172113 

  Weighted least-squares fit:  Y = 5.5 + 0.247 X  + 0.00071 X**2 

curvature versus dZ, slope < 10
  n = 52303 
  X=0, Y = 5.51 +/- 3.75 
  Weighted least-squares fit:  Y = 6.2 + 0.913 X  + 0.04925 X**2 


Number of samples 1146100
Max dz = 800
Mean dz = 45
RMS dz = 69.9714227381
100cm = 86.6772532938 percentile value of dz