Placeography:Image use policy

From Placeography

If you are uploading an image to Placeography, you must have the permission of the person who owns the copyright on the image - usually the photographer - or you must have a specific reason to believe you can upload it legally without their permission.

If people have put their images in the public domain, placed it under the GFDL, a Creative Commons license or a similar "free license", then you can upload it under the terms of that license. Attribution can and should be given on the image's page, whether or not it's technically required