curvature versus slope
  n = 177027 
  X=0, Y = 44.89 +/- 34.04 
  Weighted least-squares fit:  Y = 74.4 + 0.890 X  + -0.00901 X**2 

slope versus dZ, curvature < 5
  n = 5003 

  Weighted least-squares fit:  Y = 5.2 + 0.514 X  + 0.00097 X**2 
     at X = 100, Y = 66.2 
     effective RMSE xy = 103.7 

slope versus dZ, curvature < 15
  n = 15119 

  Weighted least-squares fit:  Y = 4.8 + 0.676 X  + -0.00025 X**2 

curvature versus dZ, slope < 10
  n = 1310 
  X=0, Y = 9.34 +/- 5.59 
  Weighted least-squares fit:  Y = 9.0 + 1.590 X  + 0.07953 X**2 


Number of samples 178392
Max dz = 900
Mean dz = 74
RMS dz = 105.1760429
100cm = 74.050966411 percentile value of dz