curvature versus slope
  n = 199900 
  X=0, Y = 62.75 +/- 26.31 
  Weighted least-squares fit:  Y = 73.6 + 1.192 X  + -0.01289 X**2 

slope versus dZ, curvature < 5
  n = 62977 

  Weighted least-squares fit:  Y = 11.3 + 0.297 X  + 0.00129 X**2 
     at X = 100, Y = 54.0 
     effective RMSE xy = 82.9 

slope versus dZ, curvature < 15
  n = 127071 

  Weighted least-squares fit:  Y = 13.6 + 0.262 X  + 0.00173 X**2 

curvature versus dZ, slope < 10
  n = 1639 
  X=0, Y = 10.98 +/- 7.49 
  Weighted least-squares fit:  Y = 10.3 + 5.469 X  + -0.64681 X**2 


Number of samples 202266
Max dz = 900
Mean dz = 43
RMS dz = 65.8938540381
100cm = 94.4558156091 percentile value of dz