How to render specific object only?

[archviz_plb]

I have a picture rendered in vray, i wanted to change the material of the brick wall to wooden material without rendering the whole image again, i researched online and achieved this result


If you notice, the big tree trunk in the middle is missing, and the leaves that are not included in the render mask are also rendered out, which consumes a lot of rendering time. Is there anyway I can just render out the wooden wall? Would love to have some more specific instructions
I have tried using Object ID, Object select, material ID, multimatte, I still cannot achieve desired result.

[vladimir_krastev]

Hi, thanks for posting. What are using in you example?

You can render only the wall by using render mask.

Another way is to use the matte properties found in V-Ray object properties.
Select everything and use right click to open the quad menu and find V-Ray properties and enable "matte" and set the alpha contribution to -1.