curvature versus slope
  n = 1042534 
  X=0, Y = 35.88 +/- 19.54 
  Weighted least-squares fit:  Y = 47.1 + 2.367 X  + -0.02597 X**2 

slope versus dZ, curvature < 5
  n = 113305 

  Weighted least-squares fit:  Y = 36.1 + 0.027 X  + 0.00350 X**2 
     at X = 100, Y = 73.7 
     effective RMSE xy = 100.9 

slope versus dZ, curvature < 15
  n = 323655 

  Weighted least-squares fit:  Y = 35.9 + 0.142 X  + 0.00237 X**2 

curvature versus dZ, slope < 10
  n = 13778 
  X=0, Y = 39.16 +/- 16.85 
  Weighted least-squares fit:  Y = 37.8 + 1.018 X  + 0.05360 X**2 


Number of samples 1055353
Max dz = 900
Mean dz = 59
RMS dz = 84.1961994392
100cm = 84.1201948542 percentile value of dz