Render drop shadows only, on a separate layer, with a transparent background

Hey guys!

I’m trying to find a way to render drop shadows on a separate layer for an animation… Couldn’t find any video tutorials elsewhere… Maybe it’s not possible at all?

Even just rendering a character with it’s drop shadow only would be fine. I followed a tutorial on a shadow pass stuff. The problem is that as a result I’m getting my characters’ drop shadows along with a mountain relief drop shadows (characters are moving on a mountain with an uneven surface), which I moved on a separate layer…

Although I have the drop shadows on a transparent background, now they are messed up with dropshadows of a mountain itself (which plays a role of a ground for characters…)

Here’s the tutorial I followed

What am I doing wrong?

P.S. If any of you could tell me any ways of exporting shadows without objects it would literally save my ass, cause I’m working on a large project, where this thing is crucial and I’ll have it as a problem all the time…

Thanks in advance