How do you handle multi-level maps?

[Sarteck]

How do you handle multi-level maps? Especially with regards to Line of Sight...

I don't mean like, a "floor 1" to "floor 2" map, but more along the lines of a pathway on one map going under/over another pathway.

E.G.:
https://imgur.com/ACGIBLU.jpg

Two north-south tunnels here go underneath an east-west sewer waterway.

At first I was thinking something along the lines of using an invisible Layer over top of the crossing. Make this layer have an Image opposite what is shown on the map. (In the example above, I'd have it show the tunnel instead of the sewer on the Invisible layer.) Then maybe I could add LoS walls oriented for the tunnel crossing, or something like that.

I was thinking something like this:
1) Have the "base" image as the bottom layer. Do NOT add LoS walls at the intersection on this base layer.
2) Add in "Sewer" layer with LoS walls oriented for sewer travel (east-west). No image needed for this layer, as it's the "default."
3) Add in "Tunnel" layer with LoS walls oriented north-south. Use an appropriate image for this layer. Hide this layer by default.

If I "Hide" a layer, would the LoS walls for that layer become inert? (E.G., if I hid the "Tunnel" layer, would players still be able to cross east-west through the sewer? Likewise, if I hid the "Sewer" layer, would players be able to cross north-south through the tunnel?)

Is something like this possible, or am I overthinking it? Should I just go with Theater of Mind to describe to the players that the tunnel doesn't end at the sewer border, and just move their tokens as the DM to the other side? How do you guys handle it? Any tips/advice welcome.

[LordEntrails]

Interesting question :)
I will await eagerly your solution :)

[Zacchaeus]

You'll have to pick one way or the other as the main route and add in walls to that one. When the PCs are traversing the other route you'll need to move them (hold SHIFT whilst you do so) from one section to the next.

Also note that the LOS has been done for that map (if I'm recognising it correctly).

[Sarteck]

I can achieve it, but not the way I originally thought.

I was misunderstanding how walls and layers work. But now that I got it, I thought of a different way.

Layer 1: Map image showing sewer, not tunnels (Base/Background image).
Layer 2: Walls, Doors, Secret Doors, Terrain
Layer 3!n: Connecting Tunnel overlap (where "n" is number of other tunnels)

Set Layers 3+ to Invisible to Everyone.
On Wall Layer, make Secret Doors around all four corners of a "pass".
"Open" these as appropriate for wherever your players are. (By default, doors blocking east-west sewer passageway are Open.)
When players come to Tunnel Crossing, set that Layer to "Visible" and toggle each of the secret doors (open to closed and vice versa)

I'm too lazy to look into the code, but it would be really awesome if someone could automate this somehow.

[Sarteck]

Here is an example of my method:

Sewer

https://i.imgur.com/0wuIgAv.png

Occluders (think that's the right term)

https://i.imgur.com/Ezlrddw.png

Default East-West passageway is "Open"

https://i.imgur.com/VnbqlQd.png

Default North-South is "Closed"

https://i.imgur.com/jqaZimH.png

But if we move to the passage leading under, first we toggle the Visibility of the passover,

https://i.imgur.com/Q957awM.png

Then we toggle the Secret Door states

https://i.imgur.com/MgzeuP5.png

and

https://i.imgur.com/5n23QkE.png

[Sarteck]

And I kind of sort of got a "dynamic" lighting effect to "work" XD

https://imgur.com/BR68mBx.gif

[Sarteck]

Gotta show one more. This one, I put a 60-foot strech of terrain in the north-south sewer corridor, overlapping each other halfway.

I think it would work out better if I did a 30-foot terrain overlapping every 15 feet instead.

https://i.imgur.com/M8WAC4B.gif

[LordEntrails]

NIce, thanks for the images :)