curvature versus slope
  n = 193393 
  X=0, Y = 52.70 +/- 24.72 
  Weighted least-squares fit:  Y = 64.2 + 1.803 X  + -0.02047 X**2 

slope versus dZ, curvature < 5
  n = 68566 

  Weighted least-squares fit:  Y = 14.3 + 0.618 X  + -0.00069 X**2 
     at X = 100, Y = 69.3 
     effective RMSE xy = 106.5 

slope versus dZ, curvature < 15
  n = 127023 

  Weighted least-squares fit:  Y = 15.4 + 0.598 X  + -0.00031 X**2 

curvature versus dZ, slope < 10
  n = 3502 
  X=0, Y = 19.39 +/- 10.63 
  Weighted least-squares fit:  Y = 18.9 + 3.120 X  + -0.47063 X**2 


Number of samples 194276
Max dz = 900
Mean dz = 52
RMS dz = 104.990475759
100cm = 92.2671868888 percentile value of dz