curvature versus slope
  n = 375075 
  X=0, Y = 42.57 +/- 28.54 
  Weighted least-squares fit:  Y = 70.7 + 1.343 X  + -0.01401 X**2 

slope versus dZ, curvature < 5
  n = 16518 

  Weighted least-squares fit:  Y = 19.1 + 0.358 X  + 0.00507 X**2 
     at X = 100, Y = 105.6 
     effective RMSE xy = 163.1 

slope versus dZ, curvature < 15
  n = 50480 

  Weighted least-squares fit:  Y = 18.4 + 0.512 X  + 0.00385 X**2 

curvature versus dZ, slope < 10
  n = 2849 
  X=0, Y = 24.34 +/- 11.05 
  Weighted least-squares fit:  Y = 23.6 + 1.661 X  + -0.03616 X**2 


Number of samples 378243
Max dz = 900
Mean dz = 93
RMS dz = 135.114766032
100cm = 65.8084881941 percentile value of dz