curvature versus slope
  n = 181574 
  X=0, Y = 43.42 +/- 31.20 
  Weighted least-squares fit:  Y = 67.8 + 1.122 X  + -0.01111 X**2 

slope versus dZ, curvature < 5
  n = 4316 

  Weighted least-squares fit:  Y = 9.3 + 0.292 X  + 0.00011 X**2 
     at X = 100, Y = 39.6 
     effective RMSE xy = 60.5 

slope versus dZ, curvature < 15
  n = 14626 

  Weighted least-squares fit:  Y = 9.8 + 0.341 X  + 0.00020 X**2 

curvature versus dZ, slope < 10
  n = 1079 
  X=0, Y = 10.63 +/- 4.96 
  Weighted least-squares fit:  Y = 9.8 + 1.590 X  + 0.01324 X**2 


Number of samples 184087
Max dz = 800
Mean dz = 58
RMS dz = 82.2009732302
100cm = 81.7352664773 percentile value of dz