These images appear to be unconvincing digital superimpositions of a large cylindrical object on photographs of Victoria Square in Hull.
I visited the square and saw the object for myself; the photographs are real and not re-touched, the object really was installed in the square. So why does it seem to be superimposed in these photographs? Perhaps it is because the object is so large and smooth compared to the buildings and other objects in the scene that it does not seem to fit. This may be part of the explanation, but I think there is also something else going on which relates to the unconscious assumptions that our brain makes when we try to make sense of visual scenes.
Of course the rest of the street scene is lit by natural daylight from above, not from the side. So the apparent inconsistency in lighting between the blade (side-lit) and the rest of the scene (top-lit) makes it appear completely out of place. It creates the false impression that the blade was not present in the scene; that the photograph is a composite of two different scenes. Many more images have appeared on the web and in the print media. Whenever they show the same side of the blade as in the photographs above, there is a tendency to misinterpret its shape and so interpret the lighting as inconsistent. The illusion could even be experienced while viewing the blade at the site, at least if one eye was closed to remove shape cues based on stereo vision.
The blade was made by turbine manufacturer Siemens and placed placed in Victoria Square as an art installation to mark the start of Hull’s year as the UK City of Culture 2017. As Hull City of Culture (https://www.hull2017.co.uk/whatson/events/blade/) states:
"Conceived by artist Nayan Kulkarni, Blade has been created for Look Up, a programme of temporary artworks created for the city’s public spaces and places.
It uses one of the first B75 rotor blades made in Hull and changes its status to that of a readymade artwork. At 75 metres it is the world’s largest, handmade fibreglass component – cast as a single element."
The Blade was removed from Victoria Square in March at the end of its exhibition period, and Siemens has yet to decide where its permanent home will be.
A more detailed discussion of this interpretation of the Blade is now published in the journal i-Perception.