curvature versus slope
  n = 530217 
  X=0, Y = 27.88 +/- 16.06 
  Weighted least-squares fit:  Y = 41.1 + 2.927 X  + -0.03239 X**2 

slope versus dZ, curvature < 5
  n = 126541 

  Weighted least-squares fit:  Y = 63.5 + 1.096 X  + -0.00407 X**2 
     at X = 100, Y = 132.4 
     effective RMSE xy = 182.5 

slope versus dZ, curvature < 15
  n = 249763 

  Weighted least-squares fit:  Y = 61.1 + 1.023 X  + -0.00278 X**2 

curvature versus dZ, slope < 10
  n = 28138 
  X=0, Y = 76.13 +/- 34.67 
  Weighted least-squares fit:  Y = 74.7 + -4.117 X  + 0.35217 X**2 


Number of samples 536142
Max dz = 900
Mean dz = 97
RMS dz = 128.39392509
100cm = 59.2279657255 percentile value of dz