Some of the best potential cityscapes a photographer can capture are “under glass.” Whether you're shooting from a hotel room, an observation tower, or an observation deck, the glass between you and the cityscape creates photographic problems when making your images.From the highest observation deck in the world, on the Shanghai Tower's 126th floor, to the One Liberty Place observation deck in Philadelphia on the 57th floor, the spectacular views from most urban observation decks can only be seen and photographed through glass.
Dealing with glass reflections at observation decks is the main problem for photographers there. It comes from the deck's internal lighting, plus interior surfaces reflecting sunlight on to the glass. Additional problems can come from visitor restrictions and maintenance.
Strictly speaking, “travel photography” could be defined as the documentation of an area's landscape, scope and sphere of activity, but I don't think that definition really tells the tale.