curvature versus slope
  n = 701402 
  X=0, Y = 33.48 +/- 28.00 
  Weighted least-squares fit:  Y = 59.6 + 1.697 X  + -0.01762 X**2 

slope versus dZ, curvature < 5
  n = 42889 
  X=0, Y = 27.52 +/- 8.58 
  Weighted least-squares fit:  Y = 28.8 + -0.026 X  + 0.00284 X**2 
     at X = 100, Y = 54.6 
     effective RMSE xy = 72.8 

slope versus dZ, curvature < 15
  n = 114022 
  X=0, Y = 27.52 +/- 8.58 
  Weighted least-squares fit:  Y = 28.6 + 0.159 X  + 0.00185 X**2 

curvature versus dZ, slope < 10
  n = 18836 
  X=0, Y = 26.78 +/- 11.53 
  Weighted least-squares fit:  Y = 27.1 + 1.291 X  + 0.06803 X**2 


Number of samples 716472
Max dz = 900
Mean dz = 64
RMS dz = 94.8577882938
100cm = 79.477774428 percentile value of dz