curvature versus slope
  n = 1571648 
  X=0, Y = 51.73 +/- 23.92 
  Weighted least-squares fit:  Y = 60.6 + 2.195 X  + -0.02511 X**2 

slope versus dZ, curvature < 5
  n = 855016 

  Weighted least-squares fit:  Y = 29.1 + -0.279 X  + 0.00315 X**2 
     at X = 100, Y = 32.6 
     effective RMSE xy = 23.3 

slope versus dZ, curvature < 15
  n = 1363824 

  Weighted least-squares fit:  Y = 29.7 + -0.296 X  + 0.00332 X**2 

curvature versus dZ, slope < 10
  n = 34003 
  X=0, Y = 26.63 +/- 14.27 
  Weighted least-squares fit:  Y = 26.5 + 0.502 X  + 0.01612 X**2 


Number of samples 1580131
Max dz = 800
Mean dz = 22
RMS dz = 29.7657521323
100cm = 99.3915061473 percentile value of dz