curvature versus slope
  n = 859581 
  X=0, Y = 26.43 +/- 20.15 
  Weighted least-squares fit:  Y = 48.1 + 2.295 X  + -0.02419 X**2 

slope versus dZ, curvature < 5
  n = 52328 

  Weighted least-squares fit:  Y = 40.4 + 0.325 X  + 0.00113 X**2 
     at X = 100, Y = 84.2 
     effective RMSE xy = 116.0 

slope versus dZ, curvature < 15
  n = 158210 

  Weighted least-squares fit:  Y = 42.5 + 0.272 X  + 0.00157 X**2 

curvature versus dZ, slope < 10
  n = 25702 
  X=0, Y = 40.05 +/- 16.98 
  Weighted least-squares fit:  Y = 41.6 + 1.754 X  + 0.01675 X**2 


Number of samples 865524
Max dz = 900
Mean dz = 72
RMS dz = 102.08329932
100cm = 77.2536636766 percentile value of dz