curvature versus slope
  n = 297636 
  X=0, Y = 45.72 +/- 31.65 
  Weighted least-squares fit:  Y = 67.3 + 1.319 X  + -0.01391 X**2 

slope versus dZ, curvature < 5
  n = 27681 

  Weighted least-squares fit:  Y = 20.8 + 0.351 X  + 0.00372 X**2 
     at X = 100, Y = 93.2 
     effective RMSE xy = 142.6 

slope versus dZ, curvature < 15
  n = 75050 

  Weighted least-squares fit:  Y = 20.7 + 0.510 X  + 0.00236 X**2 

curvature versus dZ, slope < 10
  n = 5104 
  X=0, Y = 24.95 +/- 14.24 
  Weighted least-squares fit:  Y = 22.6 + 2.691 X  + -0.05882 X**2 


Number of samples 302010
Max dz = 900
Mean dz = 84
RMS dz = 142.400842694
100cm = 73.2700903944 percentile value of dz