curvature versus slope
  n = 388096 
  X=0, Y = 10.35 +/- 8.94 
  Weighted least-squares fit:  Y = 20.1 + 3.770 X  + -0.04750 X**2 

slope versus dZ, curvature < 5
  n = 191938 
  X=0, Y = 6.64 +/- 4.07 
  Weighted least-squares fit:  Y = 6.0 + 0.222 X  + 0.00218 X**2 
     at X = 100, Y = 49.9 
     effective RMSE xy = 77.9 

slope versus dZ, curvature < 15
  n = 243273 
  X=0, Y = 6.78 +/- 4.11 
  Weighted least-squares fit:  Y = 5.9 + 0.273 X  + 0.00191 X**2 

curvature versus dZ, slope < 10
  n = 186769 
  X=0, Y = 6.80 +/- 4.09 
  Weighted least-squares fit:  Y = 6.3 + 1.310 X  + 0.00972 X**2 


Number of samples 399078
Max dz = 900
Mean dz = 20
RMS dz = 38.574603044
100cm = 96.0401224823 percentile value of dz