curvature versus slope
  n = 429485 
  X=0, Y = 35.88 +/- 25.10 
  Weighted least-squares fit:  Y = 54.9 + 2.101 X  + -0.02305 X**2 

slope versus dZ, curvature < 5
  n = 59659 

  Weighted least-squares fit:  Y = 11.7 + 0.304 X  + 0.00156 X**2 
     at X = 100, Y = 57.6 
     effective RMSE xy = 88.6 

slope versus dZ, curvature < 15
  n = 160206 

  Weighted least-squares fit:  Y = 12.6 + 0.305 X  + 0.00183 X**2 

curvature versus dZ, slope < 10
  n = 19528 
  X=0, Y = 13.28 +/- 7.87 
  Weighted least-squares fit:  Y = 12.5 + 2.099 X  + -0.01626 X**2 


Number of samples 436934
Max dz = 900
Mean dz = 48
RMS dz = 87.4356906532
100cm = 87.6839522674 percentile value of dz