curvature versus slope
  n = 125628 
  X=0, Y = 50.21 +/- 23.83 
  Weighted least-squares fit:  Y = 61.1 + 1.940 X  + -0.02124 X**2 

slope versus dZ, curvature < 5
  n = 67326 

  Weighted least-squares fit:  Y = 10.0 + 0.296 X  + 0.00255 X**2 
     at X = 100, Y = 65.1 
     effective RMSE xy = 101.0 

slope versus dZ, curvature < 15
  n = 101279 

  Weighted least-squares fit:  Y = 10.9 + 0.248 X  + 0.00405 X**2 

curvature versus dZ, slope < 10
  n = 3970 
  X=0, Y = 11.77 +/- 6.98 
  Weighted least-squares fit:  Y = 11.3 + 2.164 X  + 0.07163 X**2 


Number of samples 126520
Max dz = 900
Mean dz = 45
RMS dz = 128.292634239
100cm = 92.3909263358 percentile value of dz