Technology

What the Heck is Google Earth Doing to the Bridges of Our Fair Planet?

DiscoblogBy Veronique GreenwoodApr 14, 2011 1:17 PM

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Perusing Google Earth’s quilt of aerial images is good for hours of stalkerish fun (Find your house! Find your ex’s house!). But every now and then, Google's geo toy can also bend the fabric of reality—literally:

Something’s wrong with this picture...

Get ready for a bumpy ride!

Artist and programmer Clement Valla

has discovered 60 strange, beautiful scenes

where Google Earth’s mapping has gone awry, as you may have seen in a post on Boing Boing

. So what's really happening in these pictures? Here’s Valla's explanation:

The images are the result of mapping a 2-dimensional image onto a 3-dimensional surface. Basically, the satellite images are flat representations in which you only see the topmost object—in this case you see the bridge, and not the landmass or water below the bridge. However, the 3D models in Google Earth contain only the information for the terrain--the landmass or the bottom of the ocean. When the flat image is projected onto this 3-dimensional surface, the bridges are projected down onto the terrain below the bridge. In other words, the bridge appears to follow the terrain that it actually goes over.

The view is further complicated by the shadows in the aerial images, which cue our brains to look for depth. When 2D images overlay nicely on the 3D terrain data, these cues help everything look normal. When they don't...fascinating disaster ensues.

This one just screams for roller-coaster sound effects: WheeeOOOOOAAAAAAaaaah!

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