curvature versus slope
  n = 185879 
  X=0, Y = 12.52 +/- 7.95 
  Weighted least-squares fit:  Y = 17.7 + 4.138 X  + -0.04650 X**2 

slope versus dZ, curvature < 5
  n = 102565 
  X=0, Y = 10.87 +/- 6.14 
  Weighted least-squares fit:  Y = 8.3 + 0.213 X  + -0.00017 X**2 
     at X = 100, Y = 27.9 
     effective RMSE xy = 41.8 

slope versus dZ, curvature < 15
  n = 134190 
  X=0, Y = 10.33 +/- 6.31 
  Weighted least-squares fit:  Y = 8.1 + 0.244 X  + 0.00054 X**2 

curvature versus dZ, slope < 10
  n = 77848 
  X=0, Y = 9.80 +/- 5.06 
  Weighted least-squares fit:  Y = 9.4 + 0.548 X  + 0.11889 X**2 


Number of samples 188128
Max dz = 900
Mean dz = 19
RMS dz = 48.5695377783
100cm = 97.305026365 percentile value of dz