Columbia in Perspective
To give you an idea of the challenges facing the accident investigators, here is a photo of the layout floor where they are reassembling the debris.
Only identified parts are placed here.
It is quite shocking to see how empty the floor is, and how scattered and few the identified parts are...
Higher resolution pictures are available Here.
If you look carefully, you can see the blue outlines of the structure - looks like both upper and lower wing surfaces have a place, and the lower wing contains red markers for the landing gear doors.