How to use Catcher and many projectors in FUSION

[Devhill]

Hi everyone!
Can someone explain how to use the catcher in Fusion ? I know is a node that fusion need to "catch" the alpha channel in a 3d environment (or something similare) but i still cannot understand where connect the catcher to. The catcher has only an output and i know i can connect it to a merge 3D or an image plane for example.
When i connect it to an image plane i cannot see the image.

I am building a scene with a camera as projector (ambient light).
This is my flow: loader -> chromakey -> camera project -> merge3d = imageplane with the projected image but A BLACK BG where i pulled out the blue

Why this ?

Another question about projectors. I know that i cannot use many camera projectors in the same merge3D.
Can i use many 3dprojectors instead of camera as projector ?

Thanks !

[pingking]

stefan has made a nice tutorial for you: