curvature versus slope
  n = 381831 
  X=0, Y = 43.92 +/- 25.54 
  Weighted least-squares fit:  Y = 57.3 + 1.709 X  + -0.01773 X**2 

slope versus dZ, curvature < 5
  n = 37308 

  Weighted least-squares fit:  Y = 13.7 + 1.556 X  + -0.00412 X**2 
     at X = 100, Y = 128.1 
     effective RMSE xy = 200.0 

slope versus dZ, curvature < 15
  n = 115124 

  Weighted least-squares fit:  Y = 13.0 + 1.694 X  + -0.00579 X**2 

curvature versus dZ, slope < 10
  n = 5203 
  X=0, Y = 23.52 +/- 11.25 
  Weighted least-squares fit:  Y = 22.1 + 2.512 X  + -0.05252 X**2 


Number of samples 385314
Max dz = 900
Mean dz = 84
RMS dz = 111.525781773
100cm = 67.435390357 percentile value of dz