curvature versus slope
  n = 307374 
  X=0, Y = 44.51 +/- 20.91 
  Weighted least-squares fit:  Y = 53.7 + 2.168 X  + -0.02373 X**2 

slope versus dZ, curvature < 5
  n = 51330 

  Weighted least-squares fit:  Y = 36.3 + -0.047 X  + 0.00415 X**2 
     at X = 100, Y = 73.2 
     effective RMSE xy = 99.7 

slope versus dZ, curvature < 15
  n = 127612 

  Weighted least-squares fit:  Y = 36.5 + -0.003 X  + 0.00379 X**2 

curvature versus dZ, slope < 10
  n = 2767 
  X=0, Y = 38.63 +/- 12.16 
  Weighted least-squares fit:  Y = 38.5 + -1.477 X  + 0.26445 X**2 


Number of samples 309373
Max dz = 900
Mean dz = 58
RMS dz = 126.925174808
100cm = 86.5870648053 percentile value of dz
Mean dz (curv<=5) = 36
RMS dz (curv<=5) = 57.6714834212