curvature versus slope
  n = 107437 
  X=0, Y = 40.63 +/- 25.29 
  Weighted least-squares fit:  Y = 57.2 + 1.685 X  + -0.01709 X**2 

slope versus dZ, curvature < 5
  n = 10142 

  Weighted least-squares fit:  Y = 46.0 + 1.612 X  + -0.00515 X**2 
     at X = 100, Y = 155.7 
     effective RMSE xy = 233.7 

slope versus dZ, curvature < 15
  n = 29106 

  Weighted least-squares fit:  Y = 48.8 + 1.532 X  + -0.00436 X**2 

curvature versus dZ, slope < 10
  n = 931 
  X=0, Y = 59.35 +/- 13.14 
  Weighted least-squares fit:  Y = 58.0 + 6.731 X  + -0.68556 X**2 


Number of samples 108378
Max dz = 900
Mean dz = 126
RMS dz = 155.704848993
100cm = 41.5139603979 percentile value of dz