We all know that buildings don't always turn out like the renderings. Last-minute changes and real-life materials can all cause discrepancies between the vision and reality of a project. In our weekly Flash Forward Friday feature, we take a look at how different projects stack up.

Analogous to a painter's blank canvas, the desert landscape of Dubai has performed the role of an architectural playground for the last 15 years. A wide variety of bold and avant-garde designs — from the villa-laden Palm Jumeirah to the world's tallest building — have pushed the Emirate city onto the world stage. The realm of possibility in the city is unrestrained, so it's no surprise that some of the best global architects have decided to make their mark here.

Project rendering of The Index, image via Foster + Partners

Positioned within the Dubai International Finance Centre, an 80-storey landmark tower by Foster + Partners rose in 2011. Called The Index, the 326-metre supertall skyscraper appears slender from its west and east elevations, while it reveals a wider girth from the north and south. A double-height sky lobby and amenity space denotes the split between the building's 25 office floors and the 520 residential units above, an arrangement that allows residents to absorb views of the coast.

The Index, image retrieved from Google Street View

The building's design consists of four tapering A-frame concrete fins broken up by three piers of dark glass stretched along the wider elevations. A sunshade system shields the interiors from excessive light and heat on the south side while 12 duplex and triplex penthouse apartments crown the structure. Though the glass is perhaps darker and more uniform than initially depicted in the renderings, the final product is a faithful adaptation of Foster's overall vision for the site.

The Index (right) from the Burj Khalifa, image by Flickr user Keith Dixon via Creative Commons

We will return next Friday with another comparison!