Line of Sight over "blank" space

How does line of sight work when the line between two hexes crosses "blank" space.   Is the blank space treated as elevation 0 (doesn't interfere with line of sight at all) or as elevation infinity (blocks all line of sight)

 

For an example, consider Baron Blade Scenario 1. A line from the north end of tile 1 to the north end of tile 2 crosses an area with no map tiles.  (assume north towards the top of the page, if you are looking at the map in the scenario guide)

 

 

It hasn't come up much, maybe not at all, but I've been counting it as infinity. My justification is that, as you cannot move through it, you cannot shoot through it.

In playtesting, it was confirmed that the LOS line has to stay within the map tiles in the game or else it's blocked. No shortcutting across the open space between tiles.