curvature versus slope
  n = 216036 
  X=0, Y = 67.95 +/- 24.32 
  Weighted least-squares fit:  Y = 78.9 + 0.768 X  + -0.00773 X**2 

slope versus dZ, curvature < 5
  n = 14984 

  Weighted least-squares fit:  Y = 16.8 + 0.156 X  + 0.00244 X**2 
     at X = 100, Y = 56.8 
     effective RMSE xy = 85.2 

slope versus dZ, curvature < 15
  n = 39355 

  Weighted least-squares fit:  Y = 17.9 + 0.199 X  + 0.00260 X**2 

curvature versus dZ, slope < 10
  n = 163 
  X=0, Y = 16.61 +/- 5.87 
  Weighted least-squares fit:  Y = 16.5 + 0.125 X  + 0.11984 X**2 


Number of samples 218625
Max dz = 900
Mean dz = 79
RMS dz = 114.324100696
100cm = 71.8897655803 percentile value of dz