curvature versus slope
  n = 423185 
  X=0, Y = 24.17 +/- 21.18 
  Weighted least-squares fit:  Y = 55.4 + 2.053 X  + -0.02225 X**2 

slope versus dZ, curvature < 5
  n = 36827 

  Weighted least-squares fit:  Y = 31.7 + 0.340 X  + 0.00260 X**2 
     at X = 100, Y = 91.7 
     effective RMSE xy = 135.2 

slope versus dZ, curvature < 15
  n = 80299 

  Weighted least-squares fit:  Y = 31.3 + 0.469 X  + 0.00178 X**2 

curvature versus dZ, slope < 10
  n = 25480 
  X=0, Y = 32.58 +/- 10.17 
  Weighted least-squares fit:  Y = 33.2 + 1.257 X  + 0.07098 X**2 


Number of samples 429656
Max dz = 900
Mean dz = 80
RMS dz = 115.485929879
100cm = 72.2021803489 percentile value of dz