curvature versus slope
  n = 652138 
  X=0, Y = 42.17 +/- 25.29 
  Weighted least-squares fit:  Y = 57.9 + 1.804 X  + -0.01927 X**2 

slope versus dZ, curvature < 5
  n = 38056 

  Weighted least-squares fit:  Y = 14.2 + 1.197 X  + -0.00342 X**2 
     at X = 100, Y = 99.6 
     effective RMSE xy = 154.9 

slope versus dZ, curvature < 15
  n = 132112 

  Weighted least-squares fit:  Y = 18.4 + 1.096 X  + -0.00263 X**2 

curvature versus dZ, slope < 10
  n = 3411 
  X=0, Y = 19.61 +/- 14.84 
  Weighted least-squares fit:  Y = 22.7 + 2.198 X  + 0.03498 X**2 


Number of samples 657430
Max dz = 900
Mean dz = 78
RMS dz = 108.967885177
100cm = 72.907229667 percentile value of dz