It's technically correct to combine the sentences in that way. With the correction from the comments to your original phrase:
- We employ both 2D and 3D shape knowledge to the processing working process, which leads to efficiently distinguishing objects-A from other objects-B.
However, for a cause-and-effect, you can replace "cause, which leads to effect" with simply "To effect, cause"
- To efficiently distinguish objects-A from objects-B, we employ both 2D and 3D shape knowledge to the working process.
It could, perhaps, be more clear with:
- To efficiently distinguish objects-A from objects-B, we employ knowledge of both 2D and 3D shapes to the working process.
This removes the ambiguity as to whether you mean
apply ( both (2D) and (3D shape knowledge) )
or
apply ( both (2D) and (3D) ) shape knowledge
The second meaning is what I assume is correct, but it seems easier to understand
apply knowledge of ( both 2D and 3D ) shapes