curvature versus slope
  n = 7133968 
  X=0, Y = 38.48 +/- 27.40 
  Weighted least-squares fit:  Y = 29.7 + 3.696 X  + -0.03946 X**2 

slope versus dZ, curvature < 5
  n = 1970071 
  X=0, Y = 43.02 +/- 25.73 
  Weighted least-squares fit:  Y = 11.7 + 0.537 X  + -0.00341 X**2 
     at X = 100, Y = 31.3 
     effective RMSE xy = 45.6 

slope versus dZ, curvature < 15
  n = 3903924 
  X=0, Y = 43.02 +/- 25.73 
  Weighted least-squares fit:  Y = 13.2 + 0.443 X  + -0.00280 X**2 

curvature versus dZ, slope < 10
  n = 1301562 
  X=0, Y = 12.99 +/- 9.36 
  Weighted least-squares fit:  Y = 11.9 + 2.138 X  + -0.10224 X**2 


Number of samples 7262941
Max dz = 900
Mean dz = 23
RMS dz = 37.2424488991
100cm = 97.415440935 percentile value of dz