curvature versus slope
  n = 312915 
  X=0, Y = 19.57 +/- 13.64 
  Weighted least-squares fit:  Y = 32.7 + 3.139 X  + -0.03408 X**2 

slope versus dZ, curvature < 5
  n = 71055 

  Weighted least-squares fit:  Y = 14.2 + 0.386 X  + 0.00193 X**2 
     at X = 100, Y = 72.2 
     effective RMSE xy = 111.2 

slope versus dZ, curvature < 15
  n = 136436 

  Weighted least-squares fit:  Y = 14.1 + 0.428 X  + 0.00184 X**2 

curvature versus dZ, slope < 10
  n = 38603 
  X=0, Y = 17.12 +/- 9.98 
  Weighted least-squares fit:  Y = 15.7 + 1.616 X  + 0.05217 X**2 


Number of samples 316881
Max dz = 900
Mean dz = 45
RMS dz = 79.642953235
100cm = 88.6219116956 percentile value of dz