curvature versus slope
  n = 5589836 
  X=0, Y = 10.82 +/- 8.94 
  Weighted least-squares fit:  Y = 31.9 + 3.878 X  + -0.04459 X**2 

slope versus dZ, curvature < 5
  n = 1316725 
  X=0, Y = 19.78 +/- 13.72 
  Weighted least-squares fit:  Y = 13.9 + 0.285 X  + -0.00175 X**2 
     at X = 100, Y = 24.9 
     effective RMSE xy = 32.6 

slope versus dZ, curvature < 15
  n = 2478487 
  X=0, Y = 19.60 +/- 13.74 
  Weighted least-squares fit:  Y = 14.7 + 0.207 X  + 0.00038 X**2 

curvature versus dZ, slope < 10
  n = 764321 
  X=0, Y = 16.87 +/- 11.84 
  Weighted least-squares fit:  Y = 15.9 + 0.653 X  + 0.03659 X**2 


Number of samples 5677243
Max dz = 900
Mean dz = 32
RMS dz = 50.931326313
100cm = 93.9023924112 percentile value of dz