curvature versus slope
  n = 423481 
  X=0, Y = 55.17 +/- 26.26 
  Weighted least-squares fit:  Y = 63.8 + 1.858 X  + -0.02340 X**2 

slope versus dZ, curvature < 5
  n = 140720 

  Weighted least-squares fit:  Y = 57.2 + -0.199 X  + 0.00277 X**2 
     at X = 100, Y = 65.0 
     effective RMSE xy = 48.6 

slope versus dZ, curvature < 15
  n = 270731 

  Weighted least-squares fit:  Y = 57.4 + -0.192 X  + 0.00289 X**2 

curvature versus dZ, slope < 10
  n = 10656 
  X=0, Y = 57.68 +/- 13.34 
  Weighted least-squares fit:  Y = 57.5 + -0.921 X  + 0.18590 X**2 


Number of samples 425442
Max dz = 900
Mean dz = 54
RMS dz = 81.4493707772
100cm = 88.8560602855 percentile value of dz