curvature versus slope
  n = 329085 
  X=0, Y = 56.19 +/- 19.14 
  Weighted least-squares fit:  Y = 61.3 + 1.860 X  + -0.01838 X**2 

slope versus dZ, curvature < 5
  n = 222030 

  Weighted least-squares fit:  Y = 10.1 + 0.139 X  + 0.00223 X**2 
     at X = 100, Y = 46.3 
     effective RMSE xy = 70.9 

slope versus dZ, curvature < 15
  n = 300656 

  Weighted least-squares fit:  Y = 10.2 + 0.163 X  + 0.00209 X**2 

curvature versus dZ, slope < 10
  n = 576 
  X=0, Y = 10.80 +/- 5.57 
  Weighted least-squares fit:  Y = 10.7 + 1.237 X  + 0.13301 X**2 


Number of samples 331930
Max dz = 900
Mean dz = 25
RMS dz = 44.9777722881
100cm = 98.4367185852 percentile value of dz