curvature versus slope
  n = 663482 
  X=0, Y = 6.21 +/- 5.50 
  Weighted least-squares fit:  Y = 6.9 + 5.394 X  + -0.06266 X**2 

slope versus dZ, curvature < 5
  n = 524352 
  X=0, Y = 5.54 +/- 5.58 
  Weighted least-squares fit:  Y = 7.8 + 0.216 X  + 0.00123 X**2 
     at X = 100, Y = 41.7 
     effective RMSE xy = 64.4 

slope versus dZ, curvature < 15
  n = 620071 
  X=0, Y = 5.68 +/- 5.68 
  Weighted least-squares fit:  Y = 8.0 + 0.252 X  + 0.00104 X**2 

curvature versus dZ, slope < 10
  n = 564547 
  X=0, Y = 8.28 +/- 6.38 
  Weighted least-squares fit:  Y = 8.1 + 0.931 X  + 0.15903 X**2 


Number of samples 666085
Max dz = 900
Mean dz = 8
RMS dz = 22.3159136044
100cm = 99.5829361118 percentile value of dz