curvature versus slope
  n = 294904 
  X=0, Y = 52.54 +/- 15.85 
  Weighted least-squares fit:  Y = 54.7 + 2.050 X  + -0.02315 X**2 

slope versus dZ, curvature < 5
  n = 174991 

  Weighted least-squares fit:  Y = 50.0 + -1.025 X  + 0.01112 X**2 
     at X = 100, Y = 58.7 
     effective RMSE xy = 48.4 

slope versus dZ, curvature < 15
  n = 245837 

  Weighted least-squares fit:  Y = 50.8 + -0.991 X  + 0.01097 X**2 

curvature versus dZ, slope < 10
  n = 2041 
  X=0, Y = 45.25 +/- 15.97 
  Weighted least-squares fit:  Y = 46.6 + -2.140 X  + 0.41711 X**2 


Number of samples 299352
Max dz = 900
Mean dz = 34
RMS dz = 61.6603600379
100cm = 95.853042572 percentile value of dz