curvature versus slope
  n = 2711652 
  X=0, Y = 37.24 +/- 32.24 
  Weighted least-squares fit:  Y = 55.7 + 1.123 X  + -0.00963 X**2 

slope versus dZ, curvature < 5
  n = 79050 
  X=0, Y = 6.91 +/- 3.65 
  Weighted least-squares fit:  Y = 6.5 + 0.042 X  + 0.00244 X**2 
     at X = 100, Y = 35.1 
     effective RMSE xy = 54.2 

slope versus dZ, curvature < 15
  n = 300217 
  X=0, Y = 6.55 +/- 3.25 
  Weighted least-squares fit:  Y = 6.4 + 0.060 X  + 0.00222 X**2 

curvature versus dZ, slope < 10
  n = 255585 
  X=0, Y = 7.11 +/- 3.29 
  Weighted least-squares fit:  Y = 6.7 + 0.146 X  + -0.00039 X**2 


Number of samples 2743948
Max dz = 900
Mean dz = 333
RMS dz = 2914.91063328
100cm = 99.4357400359 percentile value of dz
Mean dz (curv<=5) = 57
RMS dz (curv<=5) = 1211.40992236