curvature versus slope
  n = 684253 
  X=0, Y = 18.89 +/- 14.20 
  Weighted least-squares fit:  Y = 35.0 + 3.537 X  + -0.04112 X**2 

slope versus dZ, curvature < 5
  n = 179003 
  X=0, Y = 7.18 +/- 5.97 
  Weighted least-squares fit:  Y = 18.6 + 0.312 X  + 0.00290 X**2 
     at X = 100, Y = 78.8 
     effective RMSE xy = 120.3 

slope versus dZ, curvature < 15
  n = 321004 
  X=0, Y = 7.40 +/- 5.16 
  Weighted least-squares fit:  Y = 18.8 + 0.365 X  + 0.00283 X**2 

curvature versus dZ, slope < 10
  n = 126408 
  X=0, Y = 19.27 +/- 13.45 
  Weighted least-squares fit:  Y = 20.2 + 1.564 X  + 0.05291 X**2 


Number of samples 695376
Max dz = 900
Mean dz = 47
RMS dz = 77.8074546557
100cm = 87.7841628126 percentile value of dz