curvature versus slope
  n = 444172 
  X=0, Y = 56.12 +/- 39.02 
  Weighted least-squares fit:  Y = 80.9 + 0.765 X  + -0.00725 X**2 

slope versus dZ, curvature < 5
  n = 8268 

  Weighted least-squares fit:  Y = 29.1 + 0.123 X  + 0.00183 X**2 
     at X = 100, Y = 59.7 
     effective RMSE xy = 81.8 

slope versus dZ, curvature < 15
  n = 30370 

  Weighted least-squares fit:  Y = 27.7 + 0.308 X  + 0.00075 X**2 

curvature versus dZ, slope < 10
  n = 1463 
  X=0, Y = 35.35 +/- 19.22 
  Weighted least-squares fit:  Y = 34.8 + 0.461 X  + 0.05604 X**2 


Number of samples 448744
Max dz = 900
Mean dz = 80
RMS dz = 110.63905278
100cm = 70.9348760095 percentile value of dz