curvature versus slope
  n = 94188 
  X=0, Y = 50.10 +/- 23.38 
  Weighted least-squares fit:  Y = 66.6 + 1.578 X  + -0.01616 X**2 

slope versus dZ, curvature < 5
  n = 17859 

  Weighted least-squares fit:  Y = 59.6 + 0.272 X  + -0.00188 X**2 
     at X = 100, Y = 68.0 
     effective RMSE xy = 51.6 

slope versus dZ, curvature < 15
  n = 41572 

  Weighted least-squares fit:  Y = 77.4 + -0.386 X  + 0.00401 X**2 

curvature versus dZ, slope < 10
  n = 53 
  X=0, Y = 58.00 +/- 8.76 
  Weighted least-squares fit:  Y = 52.4 + 10.906 X  + -0.68606 X**2 


Number of samples 94839
Max dz = 900
Mean dz = 90
RMS dz = 142.569281404
100cm = 69.8963506574 percentile value of dz