curvature versus slope
  n = 167367 
  X=0, Y = 35.44 +/- 28.36 
  Weighted least-squares fit:  Y = 66.0 + 1.705 X  + -0.01857 X**2 

slope versus dZ, curvature < 5
  n = 26887 

  Weighted least-squares fit:  Y = 8.0 + 0.771 X  + -0.00059 X**2 
     at X = 100, Y = 79.2 
     effective RMSE xy = 123.8 

slope versus dZ, curvature < 15
  n = 64612 

  Weighted least-squares fit:  Y = 8.1 + 0.905 X  + -0.00142 X**2 

curvature versus dZ, slope < 10
  n = 9414 
  X=0, Y = 11.12 +/- 7.38 
  Weighted least-squares fit:  Y = 10.7 + 2.169 X  + 0.36517 X**2 


Number of samples 170467
Max dz = 900
Mean dz = 73
RMS dz = 130.537350977
100cm = 77.2724339608 percentile value of dz