curvature versus slope
  n = 685118 
  X=0, Y = 51.45 +/- 27.70 
  Weighted least-squares fit:  Y = 66.1 + 1.456 X  + -0.01515 X**2 

slope versus dZ, curvature < 5
  n = 39157 

  Weighted least-squares fit:  Y = 25.6 + -0.040 X  + 0.00400 X**2 
     at X = 100, Y = 61.6 
     effective RMSE xy = 88.0 

slope versus dZ, curvature < 15
  n = 155173 

  Weighted least-squares fit:  Y = 25.0 + 0.047 X  + 0.00319 X**2 

curvature versus dZ, slope < 10
  n = 2451 
  X=0, Y = 24.07 +/- 11.31 
  Weighted least-squares fit:  Y = 23.1 + 1.248 X  + 0.11305 X**2 


Number of samples 694160
Max dz = 900
Mean dz = 55
RMS dz = 78.9113426574
100cm = 84.3974011755 percentile value of dz