curvature versus slope
  n = 45503 
  X=0, Y = 38.10 +/- 18.10 
  Weighted least-squares fit:  Y = 59.7 + 2.047 X  + -0.02223 X**2 

slope versus dZ, curvature < 5
  n = 6394 

  Weighted least-squares fit:  Y = 74.9 + -0.419 X  + 0.00537 X**2 
     at X = 100, Y = 86.7 
     effective RMSE xy = 68.6 

slope versus dZ, curvature < 15
  n = 14780 

  Weighted least-squares fit:  Y = 68.3 + -0.193 X  + 0.00443 X**2 

curvature versus dZ, slope < 10
  n = 88 
  X=0, Y = 92.86 +/- 14.43 
  Weighted least-squares fit:  Y = 94.4 + -1.244 X  + -0.98858 X**2 


Number of samples 45907
Max dz = 900
Mean dz = 93
RMS dz = 145.006896388
100cm = 68.3359836191 percentile value of dz