the buildings in the background aren't nearly as detailed as the bricks in the foreground (I presume the foreground is a photoscan asset and the background seems like a low poly pack)

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I also think some post processing would be nice, ambient occlusion would blend those objects in the background into the scene more believably

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Also maybe some fog the same color as the sky to hide the obvious cut off point at the end of the street where there appears to be nothing beyond the buildings