curvature versus slope
  n = 899588 
  X=0, Y = 36.25 +/- 25.21 
  Weighted least-squares fit:  Y = 36.5 + 1.288 X  + -0.00919 X**2 

slope versus dZ, curvature < 5
  n = 8228 

  Weighted least-squares fit:  Y = 1.8 + 0.401 X  + -0.00276 X**2 
     at X = 100, Y = 14.4 
     effective RMSE xy = 22.4 

slope versus dZ, curvature < 15
  n = 46344 

  Weighted least-squares fit:  Y = 2.8 + 0.306 X  + -0.00086 X**2 

curvature versus dZ, slope < 10
  n = 58164 
  X=0, Y = 4.27 +/- 2.64 
  Weighted least-squares fit:  Y = 5.1 + 0.118 X  + -0.00030 X**2 


Number of samples 930454
Max dz = 900
Mean dz = 3499
RMS dz = 8608.28130349
100cm = 99.7121835147 percentile value of dz
Mean dz (curv<=5) = 451
RMS dz (curv<=5) = 2976.67751025