curvature versus slope
  n = 797633 
  X=0, Y = 39.18 +/- 22.99 
  Weighted least-squares fit:  Y = 51.7 + 2.077 X  + -0.02197 X**2 

slope versus dZ, curvature < 5
  n = 59702 

  Weighted least-squares fit:  Y = 9.6 + 0.949 X  + -0.00326 X**2 
     at X = 100, Y = 71.9 
     effective RMSE xy = 112.0 

slope versus dZ, curvature < 15
  n = 205306 

  Weighted least-squares fit:  Y = 12.3 + 0.902 X  + -0.00254 X**2 

curvature versus dZ, slope < 10
  n = 5170 
  X=0, Y = 12.27 +/- 9.09 
  Weighted least-squares fit:  Y = 13.0 + 3.692 X  + -0.07085 X**2 


Number of samples 809372
Max dz = 900
Mean dz = 58
RMS dz = 87.965902485
100cm = 83.2903782192 percentile value of dz