Thursday, November 01, 2007

Google Earth Mapping Oddity

I was playing with Google Earth, looking at friends' houses in the NY Metro area. I scanned over to the George Washington Bridge, and noticed that with the 3-D Structures layer turned on, it looked rather cool. I rotated the plane of the view so that I was looking at it as if flying by at about 500 feet, and noticed something odd.

The program has a picture of the roadway, from satellite, and it has a graphic structure which copies the actual bridge structure. The structure is in place, but the picture of the road, instead of overlaying the bridge structure and appearing to be the actual bridge deck, instead was overlaid on the land underneath the bridge. So the picture of the road deck follows the hills below the bridge, and crosses on the surface of the water, while the structure stands proudly where the bridge itself is. See this picture, you'll see what I mean.

It seems to be a bit of an error - does the picture of an elevated surface follow the land, or does it exist at its own elevation?

For a higher-resolution version, click on the picture.