rMaternII(kappa, r, win = owin(c(0,1),c(0,1)))"owin"
    or something acceptable to as.owin."ppp").win.  The process is constructed by first
  generating a uniform Poisson point process of ``proposal'' points 
  with intensity kappa inside the window.
  Then each proposal point is marked by an ``arrival time'', a number
  uniformly distributed in $[0,1]$ independently of other variables.
  
  A proposal point is deleted if it lies within r units' distance
  of another proposal point that has an earlier arrival time.
  Otherwise it is retained.
  The retained points constitute Mat'ern's Model II.
The difference between Mat'ern's Model I and II is the italicised statement above. Model II has a higher intensity for the same parameter values.
rpoispp,
rMatClust,
rMaternI