curvature versus slope
  n = 36765 
  X=0, Y = 34.32 +/- 16.28 
  Weighted least-squares fit:  Y = 62.1 + 1.861 X  + -0.01964 X**2 

slope versus dZ, curvature < 5
  n = 3373 

  Weighted least-squares fit:  Y = 75.7 + -0.667 X  + 0.00758 X**2 
     at X = 100, Y = 84.7 
     effective RMSE xy = 59.9 

slope versus dZ, curvature < 15
  n = 7386 

  Weighted least-squares fit:  Y = 74.4 + -0.712 X  + 0.00991 X**2 

curvature versus dZ, slope < 10
  n = 116 
  X=0, Y = 70.34 +/- 16.43 
  Weighted least-squares fit:  Y = 71.7 + -2.561 X  + -0.50292 X**2 


Number of samples 37093
Max dz = 900
Mean dz = 103
RMS dz = 181.895574438
100cm = 66.2389130025 percentile value of dz