[Miscellanous / Other] Resource use and Maps

[maya]

Hello,
This is a question about resource use in map making?
Can I edit a custom model I am using in a map I am making without permission.

Suppose I want to change a models texture or add armor or other parts like a different weapon or change its hair, in other words I want to make it suitable to the style and atmosphere of my map. Is is allowed.

I want to know because if I am using many models in my map, do I need every authors permission in written (pm or mail) or is it a given that if I am providing the author explicit credits in the map I am free to edit the model for map use.
Also that model won't be circulated as a stand alone download, only for use in a map. Is it allowed, please let me know.

Also is it okay to show edited model in promotional screenshots (with proper credits off course)

Please let me know.

 

[sonofjay]

Well as long as you don't upload it then it is fine. Just give full credit to them.