shadow channel?

hello,

for compositing i need at least the shadows channel.

i was wondering how to render to elements with the new VFB in conjunction with netrendering. I tried to select desired channel(s) and save each as tga or whatever, which works fine on one workstation. but i was not able to get usable results when strip rendering the whole image with several render nodes. the tgas were saved in the original resolution not that of a single strip.

the second question i got is regarding VRayMtlWrapper or VRayProperties:
After the upper way did not work, I tried to assign a VrayMtlWrapper to the ground and one to the objects and / or adjusted the VrayProperties of the objects and the ground. but none of the procedures were successful.

I use vr 1.45.70. all objects have a VRayDisplacementMod assigned. I must strip render the whole image (one node otherwise would need 110 h!).

can anyone please help or give a rough step by step discription?

thank you in advance!
cardillac