curvature versus slope
  n = 501658 
  X=0, Y = 59.63 +/- 30.27 
  Weighted least-squares fit:  Y = 65.0 + 1.434 X  + -0.01407 X**2 

slope versus dZ, curvature < 5
  n = 8909 

  Weighted least-squares fit:  Y = 106.8 + -0.396 X  + 0.00444 X**2 
     at X = 100, Y = 111.6 
     effective RMSE xy = 50.9 

slope versus dZ, curvature < 15
  n = 46471 

  Weighted least-squares fit:  Y = 106.4 + -0.367 X  + 0.00452 X**2 

curvature versus dZ, slope < 10
  n = 680 
  X=0, Y = 100.12 +/- 42.65 
  Weighted least-squares fit:  Y = 99.8 + -0.229 X  + -0.01068 X**2 


Number of samples 503742
Max dz = 900
Mean dz = 110
RMS dz = 138.83083231
100cm = 51.369153257 percentile value of dz