curvature versus slope
  n = 207404 
  X=0, Y = 39.46 +/- 30.29 
  Weighted least-squares fit:  Y = 68.3 + 1.208 X  + -0.01268 X**2 

slope versus dZ, curvature < 5
  n = 6298 

  Weighted least-squares fit:  Y = 6.6 + 0.604 X  + 0.00054 X**2 
     at X = 100, Y = 72.4 
     effective RMSE xy = 113.2 

slope versus dZ, curvature < 15
  n = 19961 

  Weighted least-squares fit:  Y = 8.2 + 0.634 X  + 0.00028 X**2 

curvature versus dZ, slope < 10
  n = 2061 
  X=0, Y = 11.22 +/- 7.75 
  Weighted least-squares fit:  Y = 10.2 + 2.710 X  + -0.00397 X**2 


Number of samples 208864
Max dz = 900
Mean dz = 75
RMS dz = 109.32520295
100cm = 72.7956948062 percentile value of dz