curvature versus slope
  n = 120431 
  X=0, Y = 26.81 +/- 26.07 
  Weighted least-squares fit:  Y = 63.4 + 1.539 X  + -0.01620 X**2 

slope versus dZ, curvature < 5
  n = 7226 

  Weighted least-squares fit:  Y = 2.4 + 0.497 X  + 0.00058 X**2 
     at X = 100, Y = 57.9 
     effective RMSE xy = 90.9 

slope versus dZ, curvature < 15
  n = 16351 

  Weighted least-squares fit:  Y = 2.9 + 0.583 X  + 0.00037 X**2 

curvature versus dZ, slope < 10
  n = 6932 
  X=0, Y = 4.45 +/- 2.84 
  Weighted least-squares fit:  Y = 3.2 + 2.774 X  + -0.03937 X**2 


Number of samples 121629
Max dz = 900
Mean dz = 65
RMS dz = 103.130984675
100cm = 78.6194082003 percentile value of dz