How to model firing over intervening terrain at different levels?

[Schogun]

Firing up or down over terrain taking into account relative height and position of the terrain.

What rules handle this best without getting overly mathematical?

Thanks

[OSHIROmodels]

I've done it as either adding or taking away between a half and a third of the respective height difference between the target and the shooter.

[Dolnikan]

The simplest way is to just measure the actual distance. That should usually give pretty reliable results. But otherwise, it can become difficult because outside of going for a simple Pythagoras, you get wonky systems where you add the height or things like that.