Mapping Ground Zero with Lasers

securitas writes: "Amazing how the WTC disaster has shone a light on technology (pun intended). LIDAR (Light Detecting and Ranging) is the optical equivalent of RADAR. It's being used to create hyper-detailed maps of the WTC disaster site from an altitude of 5000 feet to detect shifts in the rubble as well as areas in danger of collapse."

Comments

Re:maybe offtopic

[budgenator]

not sure about any real attempt to dig it out, there's lots of problems there.
First the WTC was built in a "bathtub" because the foundation is below sea level so if the bathtub is cracked mud could rush in and de-stablize near by structures like subways, utility conduits and other building foundations. The WTC actualy re-inforced the tub internaly to prevent its colapse; now its rubble. To do this there is talk that they may have to drill through the tub and sink tie-backs into the bedrock or build cross-bracing beams and remove the rummble between the openings.
FYI Infrared lasers LIDAR is helpful here because of its excellent smoke-haze penetration and higher detail. Microwave side-looking radar might work but I think that the dust would either block or distorte the data. The sonar is probably used to probe the columns in near by buildings for hidden internal damage

Re:how is this done?

[mpe]

How do they monitor the site constatly from 5000 feet? is there a plane constantly circling around the site or is it done by a sort of balloon? can't this monitoring be achieved by satellites?

A satellite can't monitor such an area constantly, since Manhatten isn't on the equator.
The easiest way would be a teathered balloon.

CNN Map

[Alien54]

While not as neat or as detailed; this CNN map is interesting as an overview of the site.

http://www.cnn.com/SPECIALS/2001/trade.center/dama ge.map.html

Note that a High speed line would nice to have when viewing this

Google Search Stats for 9/11

[msheppard]

Zeitgeist type stuff for the 11th.