[ASM scene] Assembly graphics compo question

[Juhakoski Veera]

Hi everyone!

I was just going through this years graphics compo finalists and their unfinished screenshots and they reminded me to ask a few things about the compo rules that are a bit unclear to me.

 Can you use photographs/material you haven´t taken/created yourself?
  ->  In the compo rules it is stated that "If you are using a modeler, it is not sufficient to submit six pictures of the final picture from different view points!If you are using a photograph, take few extra shots and include them as a proof."

 this would seem to hint that you can only use your own photos and materials, but for example the 2nd placed entry this year ( http://bassboost.deviantart.com/art/Wildlife-93566620 ) was built over a royalty free image bank photo  ( http://www.sxc.hu/photo/1024317 )

and also in the compo rules it states "In addition to the image files, a text file called Readme.txt stating used techniques and sources of any material used in the entry must be submitted. If possible, we will tell the information about the techniques when showing the pictures on the big screen and when voting for them in the PMS system." and this makes it seem that it is okay to use material that is not your own if you state the source of that material.

So which is it? Is it okay to use materials you haven´t created yourself as long as you state the sources in your readme.txt or do you have to use solely your own stuff? Also I would like to ask that if it is okay to use materials from different sources - where do you draw  the line that defines whether the graphic is your creation or someone elses.

I post this question on the oldskool mailinglist since here this question has the most chance of getting clear answers. Also I apologize if this is a moronic question this has just been nagging at me for quite some time.

greetings from Lappland
-veera