curvature versus slope
  n = 186103 
  X=0, Y = 19.35 +/- 16.86 
  Weighted least-squares fit:  Y = 29.4 + 3.258 X  + -0.03216 X**2 

slope versus dZ, curvature < 5
  n = 69176 
  X=0, Y = 7.36 +/- 4.69 
  Weighted least-squares fit:  Y = 6.7 + 0.312 X  + 0.00090 X**2 
     at X = 100, Y = 46.9 
     effective RMSE xy = 73.0 

slope versus dZ, curvature < 15
  n = 116348 
  X=0, Y = 7.07 +/- 4.37 
  Weighted least-squares fit:  Y = 7.0 + 0.345 X  + 0.00062 X**2 

curvature versus dZ, slope < 10
  n = 63248 
  X=0, Y = 7.84 +/- 4.96 
  Weighted least-squares fit:  Y = 6.9 + 1.715 X  + 0.01015 X**2 


Number of samples 189109
Max dz = 900
Mean dz = 19
RMS dz = 35.4541958025
100cm = 98.1703673543 percentile value of dz