Tuesday, February 02, 2016

A curious grid in China

kw: analysis, china, machine vision, imaging

I recently happened upon a series running on the Science Channel called "What on Earth?". In an episode from last year they speculated for a 15-minute segment about this image of a funny grid pattern seen in China, in the desert west of Mongolia:

The show reported it as being first seen in 2006, but this satellite image from Google Earth was acquired May 29, 2005. The grid is big, not on the scale of the Nazca lines, perhaps, but it is 1.0x1.8 km in size, and the lines are 20 m wide. This image is centered near 40°27' N, 93°44' E. The area looks quite different, now that ten years have passed (see below).

The show segment was all speculation about what it might be. They noted that it is about 300 km west of a missile base, and it does seem logical that it is a test target for machine vision. I thought of a possibility the show doesn't mention: target acquisition when GPS is not an option, such as in the aftermath of a nuclear exchange, which would knock out GPS because of the massive EMP (electromagnetic pulse).

I noticed the disturbed area nearby on the left of the grid; here it is closer up:

The grid had apparently been recently finished, and not many buildings or vehicles remain in the area. Just six weeks earlier, it was a different story:

Here we see a lot more going on, with a pool of water near a pile of white stuff, probably chalk.

A wider view shows the partly-finished grid:

This image is from April 13, 2005. Seeing that they didn't just build the grid in a sweep from top to bottom or whatever makes me think of a further possibility. On the show they said analysts had been trying to match the pattern to street maps from various major cities. I think it possible that it actually combines sections of more than one city. It is equally possible that it is entirely made up, with various combinations of angles and spacings to test components of the vision system.

Regardless, here is how it looks today:

This image is about two years old, from March 27, 2014. It is the clearest and most complete image that Google Earth has to offer.

Rain is rare in this desert, but is being allowed to wash away the white lines. Whatever the reason is that the Chinese laid down this grid, it has clearly served its purpose.

1 comment:

Anonymous said...

The widest lines are only 90 feet wide.