Legal title doesn't refer to the name of a rendering but rather who owns it. Say a client sees your 3D rendering portfolio, falls in love with your work and commissions you for a $1500.00 rendering, and gives you a deposit on the spot (with cash, no less). The second she gives you the money, your client become the owner and title "passes" from you to her-that is, if she pays you the full $1500.00. In the real world, of course, few people pay right away. And if you're partially paid (deposit) she gives you $750.00 now and plans to pay you another $750.00 in a month - you only keep title to the rendering for as long as you actually hold on to it (that is, keep it on your server or wherever). By letting your client take the rendering, you're giving her title to it - even though she hasn't fully paid you! She still owes you $750.00, but you don't own the rendering anymore.

It is easy (and lawful) to get around this default title rule. All you have to do is state on your invoice:

Ttitle will not pass until payment is received in full or Paid in full upon completion.

This makes it clear that you are not letting your client become the owner of the rendering - even if she's already received the file - until she's paid for it in full.

Another straightforward way to prevent title passing before you're fully paid is to keep the rendering, or watermark it, until you're fully paid.