Why are you worried about using a ship (which is licensed as Creative Commons Attribution-Share Alike 2.5 Generic license), but use Lord of the Rings (which, to the best of my knowledge, isn't licensed for use at all) without even thinking about it?
It actually specifically tells you what you have to do in order to be allowed to reuse those ships:
You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
Under the following conditions:
- attribution – You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
- share alike – If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.
I'm not sure whether that last bit means
- you have to share (essentially, give your map a CC Attribution-Share Alike license as well)
- if you decide to share it, you have to do so under the CC Attribution-Share Alike license (but you're also allowed not to share it at all).
@Willem van Orange:
Simply naming the source prevents accusations of plagiarism, but that is mostly an issue when you publish books or research papers. While there are specific licences which include naming the source as a condition for use (such as indeed CC Attribution), there are many cases where you are NOT allowed to use something even if
you name the source.
The word "copyright" does NOT mean "your
right to make copies", it refers to "the author's
right to determine who is allowed to make copies". The original author would be well within their legal rights if they say "nobody else is allowed to make use of this work, at all" (which is actually the default if an author doesn't specifically say otherwise).
As an example, do you think I would be allowed to give copies of my favourite film to all my friends, just so long as I tell them the original author is some specific Hollywood studio? While I can certainly understand your feeling "oh come on, it's only a ship", legally speaking, there is no difference; both are "creative works" and receive the same legal protection. Note that reusing without
following the requirements of the license is pretty much the same thing as reusing when the work is not licensed at all. (While I strongly doubt it would actually happen, technically speaking the original author could
sue for violation of the license!)