curvature versus slope
  n = 167940 
  X=0, Y = 44.14 +/- 24.67 
  Weighted least-squares fit:  Y = 51.9 + 2.326 X  + -0.02471 X**2 

slope versus dZ, curvature < 5
  n = 97225 

  Weighted least-squares fit:  Y = 45.4 + 0.753 X  + -0.00471 X**2 
     at X = 100, Y = 73.6 
     effective RMSE xy = 91.1 

slope versus dZ, curvature < 15
  n = 140828 

  Weighted least-squares fit:  Y = 47.6 + 0.760 X  + -0.00425 X**2 

curvature versus dZ, slope < 10
  n = 11644 
  X=0, Y = 43.22 +/- 22.50 
  Weighted least-squares fit:  Y = 39.3 + 10.074 X  + -0.70822 X**2 


Number of samples 168847
Max dz = 900
Mean dz = 64
RMS dz = 99.8498873309
100cm = 74.0919293799 percentile value of dz