curvature versus slope
  n = 292116 
  X=0, Y = 19.25 +/- 16.96 
  Weighted least-squares fit:  Y = 43.1 + 2.844 X  + -0.03250 X**2 

slope versus dZ, curvature < 5
  n = 89602 
  X=0, Y = 30.97 +/- 14.29 
  Weighted least-squares fit:  Y = 28.3 + 0.184 X  + 0.00499 X**2 
     at X = 100, Y = 96.6 
     effective RMSE xy = 145.1 

slope versus dZ, curvature < 15
  n = 133083 
  X=0, Y = 30.97 +/- 14.29 
  Weighted least-squares fit:  Y = 26.9 + 0.402 X  + 0.00307 X**2 

curvature versus dZ, slope < 10
  n = 63981 
  X=0, Y = 29.87 +/- 15.29 
  Weighted least-squares fit:  Y = 29.6 + 1.032 X  + 0.14467 X**2 


Number of samples 295161
Max dz = 900
Mean dz = 63
RMS dz = 100.114933951
100cm = 80.7962434061 percentile value of dz
Mean dz (curv<=5) = 29
RMS dz (curv<=5) = 39.0896405714