curvature versus slope
  n = 1193051 
  X=0, Y = 9.30 +/- 9.87 
  Weighted least-squares fit:  Y = 31.1 + 3.480 X  + -0.03740 X**2 

slope versus dZ, curvature < 5
  n = 244471 
  X=0, Y = 8.03 +/- 3.66 
  Weighted least-squares fit:  Y = 7.8 + 0.172 X  + -0.00048 X**2 
     at X = 100, Y = 20.1 
     effective RMSE xy = 29.2 

slope versus dZ, curvature < 15
  n = 310101 
  X=0, Y = 8.02 +/- 3.68 
  Weighted least-squares fit:  Y = 7.6 + 0.246 X  + 0.00065 X**2 

curvature versus dZ, slope < 10
  n = 233632 
  X=0, Y = 8.04 +/- 3.71 
  Weighted least-squares fit:  Y = 7.9 + 1.321 X  + -0.03773 X**2 


Number of samples 1205860
Max dz = 800
Mean dz = 44
RMS dz = 70.1997150991
100cm = 87.1038926575 percentile value of dz