crest LOS questions

[trailrunner]

Hello all,

In my quest to move from SK to full ASL, I'm trying to understand LOS around hills. This seems like a fundamental concept, so I want to get a solid understanding.

I'll quote rule 10.2 in its entirety:

10.2 DIFFERENT LEVEL LOS: A lower level unit may trace a LOS into only the initial Crest Line hexside of each level above it. Likewise, a unit may trace a LOS to a lower level only if the higher unit traces its LOS through a Crest Line as it leaves its hex and this LOS never recrosses another Crest Line of the same or higher elevation [EXC: A unit may always trace a LOS through a Crest Line in an adjacent hex of lower elevation (15Y4 can fire through Y3 to Y2 and along the Y3-Z3 hex side to Z2 but i cannon fire through Z3 to AA3)]. Even if a LOS survives this test it can still be blocked by other requirmentents such as 10.23.]

1) In the first sentence, why does it say “…into only the initial Crest Line hexside….” and not “hex”? Is a “Crest Line hexside” any hexside of a hex containing a Crest Line? This may seem like I’m splitting hairs, but I think this applies to the second example: Say the darkest brown in hexes H7 and I8 did not extend to the center dot of these two hexes — say it just extended about a quarter of the way from I7 into H7 and I8. Would the unit in F9 still have LOS to H7 and I8? Or would the first hex at the dark brown level that it would have LOS to be I7?

2) In the second sentence, I’m having trouble understanding “…traces its LOS through a Crest Line as it leaves its hex…” What does “as it leaves its hex” mean? Where does it have to cross the Crest Line to qualify as “leav[ing] its hex.” A literal interpretation of this is that the Crest Line would have to be coincident with the hexside, but I’m sure this isn’t the intent. Does the Crest Line therefore have to be in the unit’s hex? I don’t think so, because in that case, the wording would be “traces its LOS through a Crest Line before it leaves its hex.” Does the Crest Line have to be in the next, adjacent hex? I don’t think so, because in that case, the wording would be “traces its LOS through a Crest Line in the first, adjacent hex after leaving the unit’s hex.” So what does “as it leaves its hex” mean?

3) In the first example, why doesn’t the unit in Y4 have LOS to AA3, if it has LOS to Z2? What is the difference in these two cases? I’m assuming that the road does not matter.

Thanks very much in advance.

 

[Robin Reeve]

The rule simply says that you cannot see a higher hill hex if it doesn't have a crest hexside crossed by your LOS.
It is what is commonly called the "plateau effect" of the ASL hills rules.

 

[Robin Reeve]

3) Y4 LOS to AA3 has no crest hexside; same level hex Z3 blocks LOS to lower AA3 hex.

 

[klasmalmstrom]

Say the darkest brown in hexes H7 and I8 did not extend to the center dot of these two hexes — say it just extended about a quarter of the way from I7 into H7 and I8.

Then those hexes would be drawn incorrectly. The highest terrain in a hex normally covers the center dot, with the exception of some older boards and river edges.

Would the unit in F9 still have LOS to H7 and I8? Or would the first hex at the dark brown level that it would have LOS to be I7?

No. Yes.

 

[klasmalmstrom]

What does “as it leaves its hex” mean? Where does it have to cross the Crest Line to qualify as “leav[ing] its hex.” A literal interpretation of this is that the Crest Line would have to be coincident with the hexside, but I’m sure this isn’t the intent. Does the Crest Line therefore have to be in the unit’s hex?

Yes.

3) In the first example, why doesn’t the unit in Y4 have LOS to AA3, if it has LOS to Z2? What is the difference in these two cases? I’m assuming that the road does not matter.

Y3 is at a lower elevation compared to Y4, where as Z3 is not (it is at the same elevation as Y4). See the EXC in B10.2.

[EXC: A unit may always trace a LOS through a Crest Line in an adjacent hex of lower elevation (15Y4 can fire through Y3 to Y2 and along the Y3-Z3 hexside to Z2 but it cannot fire through Z3 to AA3)] [/QUOTE]

 

[Binchois]

3) In the first example, why doesn’t the unit in Y4 have LOS to AA3, if it has LOS to Z2? What is the difference in these two cases? I’m assuming that the road does not matter.

15Y4 to Z2 is interesting case. I can accept the idea that LOS is clear, I am not exactly sure by what rule this is so (Klas?). Would a LOS drawn ever-so-slightly clockwise, so no longer exactly along the hexside (assume same artwork crossed) still be clear? I would think not.

Y3 is Level 1 and Z3 is Level 2, so the answer is probably similar to Cliff hexsides. Since the two hexes are at different levels, LOS drawn down the line are considered at the lower level (B11.2).

Board 15 is actually a tricky (but good) one to use as an EXample as it includes Crest Line hexsides that are atypical on more-recently drawn boards (where the crest line is drawn slightly outside of the hex). I think mapmakers now try to avoid these, keeping the crest lines internal to the hex containing the higher level.

 

[Sparafucil3]

Lets not also forget you can trace LOS to the "Crest 'Location'" of hex and target the same even if no unit occupies the hex. Recall of course, you can't hurt a Unit IN the Gully with HE as that is specific and limited to the "above ground" location but you can WP him to hell. -- jim (really, I am still not bitter about this bad decision at all)

 

[klasmalmstrom]

15Y4 to Z2 is interesting case. I can accept the idea that LOS is clear, I am not exactly sure by what rule this is so (Klas?).

B10.2:
"A unit may always trace a LOS through a Crest Line in an adjacent hex of lower elevation..."

I guess the LOS along the Y3-Z3 is considered to be "through a Crest Line in an adjacent hex of lower elevation" - thus the LOS is ok.

Would a LOS drawn ever-so-slightly clockwise, so no longer exactly along the hexside (assume same artwork crossed) still be clear? I would think not.

No, then it would only go through Z3.

Board 15 is actually a tricky (but good) one to use as an EXample as it includes Crest Line hexsides that are atypical on more-recently drawn boards (where the crest line is drawn slightly outside of the hex). I think mapmakers now try to avoid these, keeping the crest lines internal to the hex containing the higher level.

With the exception of Rivers, usually.

I think that the exception in B10.2 is there to handle these "legacy" boards (and rivers) where the crest line is drawn slightly in the "next" hex.

 

[Binchois]

B10.2:
"A unit may always trace a LOS through a Crest Line in an adjacent hex of lower elevation..."

I guess the LOS along the Y3-Z3 is considered to be "through a Crest Line in an adjacent hex of lower elevation" - thus the LOS is ok.



No, then it would only go through Z3.



With the exception of Rivers, usually.

I think that the exception in B10.2 is there to handle these "legacy" boards (and rivers) where the crest line is drawn slightly in the "next" hex.

I guess there is an attempted distinction (now avoided) between true Crest Line hexsides (like 15Y3/Y4) and in-hex Crest Lines (like within 15Z3). Y4's Level 2 is achieved at the hexside whereas Z3's Level 2 is achieved within the hex. Thus the little bit of Level 2 which exists at the vertex must be considered as part of the Y3/Y4 hexside and not part of the Y3/Z3 hexside when drawn along the latter.

 

[trailrunner]

Then those hexes would be drawn incorrectly. The highest terrain in a hex normally covers the center dot, with the exception of some older boards and river edges.

I did not realize this. This makes thing more straightforward and intuitive.

I also did not realize Z3 was at the same level as Y4. The center dot is in the road, and with the depiction of the crest line, it's not obvious.

This has been very helpful.

 

[klasmalmstrom]

I guess there is an attempted distinction (now avoided) between true Crest Line hexsides (like 15Y3/Y4) and in-hex Crest Lines (like within 15Z3). Y4's Level 2 is achieved at the hexside whereas Z3's Level 2 is achieved within the hex.

I am not sure I follow what you mean here. Both Y4 and Z3 are Level 2, because the center dot is in Level 2 terrain (disregarding the fact the in Z3 it is really on the road. ) - but I suspect you might be meaning something else.

hus the little bit of Level 2 which exists at the vertex must be considered as part of the Y3/Y4 hexside and not part of the Y3/Z3 hexside when drawn along the latter.

I think one can see it like this - the Level 2 terrain in Z3 when the LOS is drawn along the Y3-Z3 hexside is not enough to block the LOS because it is not visible on both sides of the LOS string. On hex Y3 side it would be through a hex of lower elevation - hence the LOS is clear by the EXC in B10.2.

But since the EXC in B10.2 specifically calls out this LOS to be clear, I guess the reason does not really matter.

 

[klasmalmstrom]

I also did not realize Z3 was at the same level as Y4. The center dot is in the road, and with the depiction of the crest line, it's not obvious.

Granted, but the way the Crest Line is drawn in Z3 it is (IMO) pretty clear that the dot is meant to be on Level 2 terrain.

 

[EJ1]

Thanks for this discussion. I believe I used VASL properly, and I see that VASL shows the LOS from 15Y4 to 15Z2 to be blocked. Love this game. Cheers

 

[klasmalmstrom]

Thanks for this discussion. I believe I used VASL properly, and I see that VASL shows the LOS from 15Y4 to 15Z2 to be

I think that is because VASL "sees" the Level 2 terrain on both sides of the LOS string, and it has no exception built in for this situation.

 

[fanatic+1]

Thanks for this discussion. I believe I used VASL properly, and I see that VASL shows the LOS from 15Y4 to 15Z2 to be blocked. Love this game. Cheers

View attachment 6589

I am not sure the VASL LOS function is correct in this case. My understanding is that the LOS from Y4 is not subject to the "plateau effect" if through Y3 and is subject to the "plateau effect" if through Z3. I believe a LOS along the hexspine between Y3 and Z3 is still clear per A6.1 (the blocking level 2 terrain in Z3 is not inherent and is not on both sides of the hexspine).

 

[klasmalmstrom]

I believe a LOS along the hexspine between Y3 and Z3 is still clear per A6.1 (the blocking level 2 terrain in Z3 is not inherent and is not on both sides of the hexspine).

It is clear - the EXC in B10.2 spells it put explicitly. See the quote in post #5 above.