curvature versus slope
  n = 439278 
  X=0, Y = 19.30 +/- 13.70 
  Weighted least-squares fit:  Y = 35.9 + 3.060 X  + -0.03424 X**2 

slope versus dZ, curvature < 5
  n = 96489 
  X=0, Y = 1.87 +/- 1.36 
  Weighted least-squares fit:  Y = 5.7 + 0.279 X  + 0.00186 X**2 
     at X = 100, Y = 52.2 
     effective RMSE xy = 81.5 

slope versus dZ, curvature < 15
  n = 180651 
  X=0, Y = 4.36 +/- 3.85 
  Weighted least-squares fit:  Y = 6.6 + 0.324 X  + 0.00171 X**2 

curvature versus dZ, slope < 10
  n = 48692 
  X=0, Y = 7.40 +/- 5.29 
  Weighted least-squares fit:  Y = 7.0 + 2.100 X  + 0.03606 X**2 


Number of samples 442423
Max dz = 900
Mean dz = 34
RMS dz = 68.0441033448
100cm = 92.9232883462 percentile value of dz