curvature versus slope
  n = 851242 
  X=0, Y = 9.98 +/- 7.03 
  Weighted least-squares fit:  Y = 10.8 + 4.599 X  + -0.05174 X**2 

slope versus dZ, curvature < 5
  n = 514665 
  X=0, Y = 6.53 +/- 4.33 
  Weighted least-squares fit:  Y = 7.1 + 0.171 X  + 0.00033 X**2 
     at X = 100, Y = 27.6 
     effective RMSE xy = 41.8 

slope versus dZ, curvature < 15
  n = 700766 
  X=0, Y = 6.26 +/- 4.08 
  Weighted least-squares fit:  Y = 7.1 + 0.218 X  + 0.00052 X**2 

curvature versus dZ, slope < 10
  n = 556160 
  X=0, Y = 7.52 +/- 4.65 
  Weighted least-squares fit:  Y = 6.7 + 1.660 X  + -0.03170 X**2 


Number of samples 862881
Max dz = 900
Mean dz = 12
RMS dz = 31.336879232
100cm = 98.5015314974 percentile value of dz