curvature versus slope
  n = 280293 
  X=0, Y = 39.21 +/- 27.38 
  Weighted least-squares fit:  Y = 64.6 + 1.412 X  + -0.01452 X**2 

slope versus dZ, curvature < 5
  n = 15761 

  Weighted least-squares fit:  Y = 5.7 + 0.418 X  + 0.00089 X**2 
     at X = 100, Y = 56.4 
     effective RMSE xy = 88.2 

slope versus dZ, curvature < 15
  n = 43619 

  Weighted least-squares fit:  Y = 6.8 + 0.473 X  + 0.00077 X**2 

curvature versus dZ, slope < 10
  n = 2226 
  X=0, Y = 9.27 +/- 5.65 
  Weighted least-squares fit:  Y = 7.6 + 3.302 X  + 0.00030 X**2 


Number of samples 282340
Max dz = 900
Mean dz = 58
RMS dz = 103.493961176
100cm = 83.3339236382 percentile value of dz