curvature versus slope
  n = 262302 
  X=0, Y = 12.76 +/- 8.72 
  Weighted least-squares fit:  Y = 20.4 + 4.010 X  + -0.04515 X**2 

slope versus dZ, curvature < 5
  n = 136124 
  X=0, Y = 11.07 +/- 6.58 
  Weighted least-squares fit:  Y = 8.2 + 0.029 X  + 0.00254 X**2 
     at X = 100, Y = 36.6 
     effective RMSE xy = 56.0 

slope versus dZ, curvature < 15
  n = 176066 
  X=0, Y = 10.97 +/- 6.39 
  Weighted least-squares fit:  Y = 7.7 + 0.126 X  + 0.00199 X**2 

curvature versus dZ, slope < 10
  n = 101720 
  X=0, Y = 8.90 +/- 5.15 
  Weighted least-squares fit:  Y = 8.3 + 1.203 X  + 0.04036 X**2 


Number of samples 266838
Max dz = 900
Mean dz = 20
RMS dz = 44.0794736811
100cm = 96.6451554876 percentile value of dz