Rayswitcher material is correct choise, but you need to apply it to your oil tank object, not to ground plane with shadowcatcher material.
Why ? Unless you worded this confusingly and I understand you incorrectly, by doing what you suggest, you alter the GI of your object too, which most often isn't wanted (the more complicated the object is, the less...)
Edit: Ah...I understand you. You suggested correct solution to "exactly" what he is asking (avoid GI from object on shadowcatcher plane). But that's Band-Aid for wrong setup, not correct strategy, as you DO want GI on shadowcatcher, just not incorrect (from overblown albedo) GI.
Shadowcatcher on the plane, inside Rayswitch is the correct approach. Jens, can you post your setup ?
I do this all the time for my studio renderings with no issues. The GI version of shadowcatcher in Rayswitch will be dark version of the Backplate (to simulate correct albedo light-bounce for contact shadows). Also, make sure the white paint of your object is correct albedo.
By the way this shows that the Shadowcatcher UI design is not correct imho, because 99perc. of times, it requires Rayswitch also in combination. So those control could have easily been integrated at least for GI. I understand the purity of the design this way, but it's just no practical. Instead it has some nonsensical shadow multiplier (which doesn't affect albedo, but only post-produces the resulting shadows).
« Last Edit: 2017-07-05, 21:58:19 by Juraj_Talcik »
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