Learn me more about copyright and duplicated item.

Hi,
Could anyone explain details about copyright matters. Actully, when it works.

I am actually a 3d artist, and software i use is zbrush, iclone and sometimes cinema 4d for my animtion work.so, All the item in now my portpolio in videohive (it has now reached more than 300 items) has raw files( in 3d, it is base mesh files obj format, motion capture bvh files, etc).

What if i take a base mesh( 3d artist will know about it) from a site and sculpt it with my imagination and give a new texture and color and animate it and submitted in videohive. Will it be under copyright?

More clearly, Suppose, i take a parrrot 3d model from a site, and i sculpt the parrot with my imagination by adding crest in parrot’s head and change complete texture and color of parrot and give a new look the parrot.

So, my question is - will be parrot under copyright?

Another different example: i know that i cannot submit comic chracter “spiderman” because it has copyright issues. But what if i sculpt the spiderman 3d model with my imgination by adding horn in his head or something like that, i mean i give a new look the chracter that nobody can recognise that it is spiderman at all by changing shape and color even animation.

Will it be still be under copyright? Kindly let me know. Thanks

I’m not a 3D expert or a lawyer but, if you are building out from/on top of someone else’s file (assuming that item doesn’t have a free for commercial license), then in its rawest format that would be breaching copyright