curvature versus slope
  n = 678333 
  X=0, Y = 22.65 +/- 18.08 
  Weighted least-squares fit:  Y = 42.3 + 2.887 X  + -0.03252 X**2 

slope versus dZ, curvature < 5
  n = 137398 
  X=0, Y = 7.16 +/- 3.27 
  Weighted least-squares fit:  Y = 14.1 + 0.141 X  + 0.00326 X**2 
     at X = 100, Y = 60.8 
     effective RMSE xy = 93.0 

slope versus dZ, curvature < 15
  n = 244640 
  X=0, Y = 7.16 +/- 3.27 
  Weighted least-squares fit:  Y = 13.3 + 0.319 X  + 0.00248 X**2 

curvature versus dZ, slope < 10
  n = 93711 
  X=0, Y = 13.38 +/- 8.87 
  Weighted least-squares fit:  Y = 12.4 + 2.785 X  + -0.03555 X**2 


Number of samples 692551
Max dz = 900
Mean dz = 52
RMS dz = 84.4748483278
100cm = 83.8849413256 percentile value of dz