why some hexes are immune to other hexes' return fire?

[Tcao]

I noticed that sometime a wired battle resolution can happen. Units in Hex A released deadly volley of fire toward the enemy at Hex B, but the units in Hex B cannot see where the shooter at, and cannot return fire.

I understand IRL things like that could happen. But I still would like to hear the Dev team's comment on the mechanism behind this, because this kind of Phenomenon can create some very annoying or frustrating experience.

I guess the whole issue is caused by LOS
example 1: "Regulars Forward" , Using M1A1 as a reference unit, Hex 1502 has a 18 LOS on Hex 1804. But from 1804 perspective, it has 0 on 1502.

I had a 13 tanks T80 Co sit at 1804. My opponent moved a M1 plt at 1502. Then the next 10min saw the M1A1 shoot at the T-80 Co one by one. Slowly reduced the 13 tanks to 6. By then the shot stopped because it considered that a " Six tank Company" is small enough to be concealed from M1A1

los.jpg (476.01 KiB) Viewed 793 times

[Tcao]

example 2: Scenario "The great escape"

an NVA T-72m Co. rushed down the hill from hex 1209. I had a M1 plt take cover at hex 1515. My M1 plt fired at the leading BMP co and exposed himself. Then the NVA T-72m co fired several salvo of fire toward the M1. Knocked out all 4 M1s at 3500m distance. M1 plt cannot see the shooter.

los 2.jpg (756.14 KiB) Viewed 791 times

[cbelva]

I will give you my 2 cents as to what I believe is going on. However, the developers would give the more definitive answer. There are many factors that play into LOS, sighting, and spotting. Cover and concealment ratings of the hex, size of the target in the hex, sighting capabilities of the unit, distance, lighting, and others. In the two examples you gave, it appears to me that the hexes which doesn't have reciprocal sighting is due to the cover and concealment ratings of the hex. In both examples, the cover and concealment ratings are above 90% making it hard for the unit to see into the target hex from their hex. As I move the unit close, it eventually gets close enough to be able to see into the hex somewhat.

If you feel you have a situation where the spotting/sighting is incorrect, please sent us a saved game of the specific situation descripting what you think is wrong and we can have a developer take a look at it.

Being fired upon and not knowing where the fire is coming from is a real-life situation. It is very frustrating and deadly t the troops being fired upon.

[Comcikda]

From my experience in other simulators, the fire and dust from the cannon is enough to expose the firing unit. Since IR smoke does not exist in FCSS, it is possible for the firing and fired units to spot the enemy if the distance allows. So they should at least know the general angle of the shooter and then focus on searching specific angle .
To avoid this frustrating situation, I think a los modifier could be given to the unit being shot at.

[WildCatNL]

Units in Hex A released deadly volley of fire toward the enemy at Hex B, but the units in Hex B cannot see where the shooter at, and cannot return fire.

[...] But I still would like to hear the Dev team's comment on the mechanism behind this

Thanks for the great example and solid data. It is indeed line-of-sight that is making the difference here.

First example:
- hex 1502: forest hex, elevation 4, M1 platoon
- hex 1804: partially open hex, elevation 3, T-80 coy

Second example:
- hex 1209: full forest hex, elevation 5, T-72 coy
- hex 1515: partial forest hex, elevation 3, M1 platoon

The game performs a line-of-sight check in 3D to the center of the target hex from the optimal position in the spotter's hex, which typically is the forward edge of the hex.
The game applies this "spotter's advantage" to represent spotting units being able to position themselves at the edge of a forest. a town or a hill top for an optimal view outside the hex. In other words, a spotting unit is not severely disadvantaged by a dense forest, a built-up area or a hex step in the same hex.
The "target" does get the maximum concealment bonus from a forest or built up area, or the (reverse) slope by sitting in the center of the hex.

That's why in these situations, the unit sitting higher in a hex with plenty of concealment can occupy great shooting positions, make kills, roll back and remain (almost) invisible. And the unit on relatively lower hex with less concealment struggles to survive, because it cannot look into the target hex's center nor can it truly hide in the hex that offers less concealment, and is easier to look into from above.

As you noticed, the unit's number and size of the vehicles also affect how 'spottable' the unit is.

The game is designed to do this.
Occupying great terrain (elevated position, maximum concealment) makes a difference, and occasionally can make up for superiority of numbers and weapon systems.

[nijis]

I understand that the firing unit can roll forward to an optimum position, shoot, and roll back. But should not the targeted unit have a brief window of opportunity to return fire to that optimum position before the enemy rolls back, especially if it can be presumed to have some units on overwatch (say, it's stationary or moving deliberately)?

[CapnDarwin]

I think the issue is you have a fundamental difference in the ability to spot each other to get a shot off. Each subunit has a chance to spot enemy subunits. Depending on the terrain each unit is in, the elevation change, and the range, the spotting can vary.