Source: http://designyoutrust.com/2014/01/dad-spends-7-years-on-incredibly-detailed-maze/
Not citing the source of photos, or using copyrighted photos, is plagiarism. Here is a post on why this is bad, and here is how easy it is to find allowed photos.
In this case he's just sharing some stuff which he's not claiming as his own, so that's not plagiarism. Copyright infringement isn't necessarily plagiarism. Though he could have linked to a source.