Kuro5hin.org: technology and culture, from the trenches
create account | help/FAQ | contact | links | search | IRC | site news
[ Everything | Diaries | Technology | Science | Culture | Politics | Media | News | Internet | Op-Ed | Fiction | Meta | MLP ]
We need your support: buy an ad | premium membership

Science, Technology, and the World Trade Center

By theR in Technology
Thu Oct 11, 2001 at 06:51:10 AM EST
Tags: Science (all tags)

If you are like me, after witnessing the events of September 11th, 2001, there were many things running through your mind. Virtually everyone in the U.S. and many people around the world knew people that were at or near the World Trade Center or the Pentagon on a regular basis. Even for those who did not know any of the victims, you often do not need to look far to find a friend or relative that did know someone.

I had and still have many feelings about what happened. That is not what this is about. I also had many questions, one being, "How will they ever find these people, buried beneath tons of rubble?" The task is a difficult and presumably gruesome one. It is made more difficult by the sheer amount of debris and obliteration of multiple buildings. How do you figure out where to dig and search for the remains of the victims, all while keeping the people doing the recovery safe? This is about one small piece of a puzzle that has numerous pieces, many being more important than that one small piece. Hopefully, this one piece will help.

This story revolves around the National Geodetic Survey (NGS), which is part of the National Ocean Service (NOS), which in turn is a part of the National Oceanic and Atmospheric Administration (NOAA), which in turn is part of the Department of Commerce (DOC). A wonderful example of government bureaucracy at its best. This is also about how specific technology will hopefully aid in the recovery of remains, as well as clearing and possibly rebuilding once that point is reached.

The National Geodetic Survey has a few main functions that it currently performs:

  • Define and manage the National Spatial Reference System.
  • Perform aerial photography surveys of airports within the U.S. and U.S. possessions to position obstructions and aids to air travel, with the end result being airport obstruction charts.
  • Mapping the coastal U.S. and its possessions with the purpose of constructing navigational charts.
  • "Developing standards and specifications for conducting geodetic surveys, coordinates the development and application of new surveying instrumentation and procedures, and conducts outreach activities including technical workshops conducted throughout the United States and an advisory program conducted with several states."
(Paraphrasing and direct quote from the "Who We Are" page.)

When I first heard that pilots from the NOAA Corps would be flying over the destroyed World Trade Center and taking photographs similar to the ones for use making airport obstruction charts, I wondered what the possible reason could be. This didn't seem to fit with the mission of NGS. I soon learned the purpose of these flights, and NOAA has recently shared them on the web in a press release.

NGS has been given the task of mapping the area to aid in recovery and cleanup. Using a special Kodak film that cuts down on smoke and haze, the pilots overflew and photographed the Trade Center wreckage on September 23rd and 26th at an altitude of 5,000 or 6,000 feet (about one mile), after previous work by NGS survey crews beginning on September 15th. Using the photographs and survey data taken, this data will be "used to provide a very accurate geographic network", to aid in finding where things are, such as support structures, elevator shafts, garage areas, and storage areas, so that recovery efforts can be concentrated in the correct locations. With the amount of destruction, there are very few points of reference, and I am told that, once the data has been processed, the locations of these specified areas will be plotted with accuracy to about one meter. In addition, determination of heights and depths into the ground will be sought so cleanup crews can know approximately how much debris must be removed, the size and position needed for the cranes, and whether they must beware of flooding from the surrounding waterways.

There is a fairly detailed summary on the NOAA news page showing what sort of technology was used to assist in the collection of the data. GPS was used to position ground and airborne mapping sensors, fixing lattitude, longtitude, and height within five centimeters. Two nearby Continuously Operating Reference Stations were also used for data collection. These provide continuous "carrier phase and code range measurements in support of 3-dimensional positioning activities throughout the United States and its territories." The aerial photographs were taken using a modified Cessna Citation aircraft.

The first result of the data collection was already completed at the time of the press release, and images from three different angles can be seen here, here, and here. The different colors represent heights, and the key can be seen on the NOAA news page. These images are known as LIDAR images, or Light Detection and Ranging. Basically, by measuring the round trip time of a laser pulse from the aircraft to the ground, it allows a fairly accurate elevation to be determined much more quickly than past methods.

The photos that were taken will undergo further processing, with the same software that is used for airport obstruction charts, called SOCET. With the use of high end workstation hardware, this software will be used to process digital photos using three dimensions for fairly precise measurements that may greatly aid recovery efforts. The largest image that had been on the web is much larger than the one linked to above and provides much better detail, but due to unforseen circumstances, the 14MB image is no longer available for viewing at the NOAA website. The images that will be used for processing will be many times larger, as a format other than jpg will be used to prevent data loss.

As the press release states, a similar flyover took place at the Pentagon. Needless to say, the Pentagon photos have not been made available to the public. It may be presumed that, since the recover of remains is a considerably smaller task at the Pentagon than the World Trade Center, the Pentagon may hope to use any data such as plotting where structural supports once stood to help the rebuilding effort take place as quickly as possible. This is purely conjecture, however.

Hopefully, the efforts of NGS, NOAA, NOAA Corps, and everybody else involved, will make the unenviable task of cleanup and recovery a little easier, and will help give some sort of peace to those that may never really know peace again -- those that are waiting for some sort of remains and ultimate confirmation that their loved ones are no longer with us. Obviously, those that are in the trenches deserve the credit, but this just seemed like one of those small stories that was worth sharing.


Voxel dot net
o Managed Hosting
o VoxCAST Content Delivery
o Raw Infrastructure


Do stories have to provide opportunity for discussion to be worth posting?
o Yes 16%
o No 83%

Votes: 55
Results | Other Polls

Related Links
o National Geodetic Survey
o National Ocean Service
o National Oceanic and Atmospheric Administration
o Department of Commerce
o few main functions that it currently performs
o NOAA Corps
o a press release
o photograph ed
o NOAA news page
o Continuous ly Operating Reference Stations
o a modified Cessna Citation aircraft
o here
o here [2]
o here [3]
o LIDAR images
o The photos
o Also by theR

Display: Sort:
Science, Technology, and the World Trade Center | 17 comments (13 topical, 4 editorial, 0 hidden)
unforseen? or unknown? (none / 0) (#4)
by delmoi on Thu Oct 11, 2001 at 12:29:38 AM EST

due to unforseen circumstances, the 14MB image is no longer available for viewing at the NOAA website.

Care to elaborate? Or did you mean 'unknown'?

Btw, if anyone wants to host it, I have a copy of the 14megger.
"'argumentation' is not a word, idiot." -- thelizman
unforseen would be it (none / 0) (#5)
by thecabinet on Thu Oct 11, 2001 at 12:41:14 AM EST

The 14megger is still there, it's just been renamed and apparently access to it has been denied:

Take a look at http://www.noaanews.noaa.gov/stories/images/, and you'll see a file called wtc-photo.jpg.old

They probably weren't prepared to handle a multitude of people downloading a 14MB image, so it's been taken offline for now. Might try back in a few (day|week|month)s...

[ Parent ]

Poll Response (none / 0) (#7)
by mcherm on Thu Oct 11, 2001 at 08:55:08 AM EST

No, I don't think stories have to allow discussion for them to be valuable enough for posting. But they'd better be PRETTY DARN GOOD! For instance, the recent stories by EdFox on airplane safety and anti-hijacking technologies were VERY informative and written by someone informed enough to qualify as an expert. I would have voted them up even if there had been no way for people to comment on them.

But these stories were made even BETTER by the contributions a number of thoughtful people made in the discussions. Kuro5hin is a discussion site, and it is really designed (moderation system, etc) to encourage thoughtful, insightful, and sometimes humerous discussions. I would say that 98% of stories which AREN'T going to be discussed are not worth posting (excepting the MLP category, which is different).

So I'd say yes: it's OK to post a REALLY GOOD story that no one is going to discuss... I read the stories here, and many of them are quite good. But it's even BETTER to raise a good question or two so we can get a lively discussion going.

Just my opinion... please reply to this with your own thoughts: maybe ;-) we can get a discussion going!

-- Michael Chermside

I'm gonna get a swelled head! (none / 0) (#13)
by EdFox on Fri Oct 12, 2001 at 02:24:03 AM EST

If you guys don't stop, I'm gonna be insufferable. :)

Anyway, an excellent and very detailed story, theR. I was unaware that something as fast as a Citation could be a good geodetic photography platform. I was also unaware of how the obstruction charts that keep my tail out of the trees every day were made. Learn something every day.

This article deserved to be FP news without the horrible backdrop of current events. The WTC LIDAR pictures made me cry... again.


[ Parent ]
Thanks (none / 0) (#14)
by theR on Fri Oct 12, 2001 at 11:47:13 AM EST

Actually, obstruction charts of the recent past were most likely made with analytical plotters similar to this one, though not exactly the same. The move away from the plotters was begun fairly recently and is not 100% complete yet. There are also some airports that do their own charts, and I have no idea what methods they use, although I would guess it's simply contracted out. Except for those airports that do their own, NGS does all the commercial airports in the U.S. and its territories as far as I know.

[ Parent ]
Re: Science, Technology, and the WTC (5.00 / 2) (#8)
by ezk23 on Thu Oct 11, 2001 at 03:24:13 PM EST

Regarding your question "How will they ever find these people, buried beneath tons of rubble?" The answer is grim and doesn't involve high tech imaging.

The people in the airplanes and offices which were hit directly +/- 5 stories were instantly vaporized. Fatalities resulting from the collapse of both towers were a result of bodies being smashed to a pulp and shredded. FDNY, as of Oct 11, is still fighting fires in the rubble. This most likely means that any bodies caught in the rubble have since been incinerated.

FEMA discontinued search and rescue around Sept 30. This, combined with the fact there are no disease issues in the area, as well as an agressive phase of rebuilding and structural assesment emphasises what I've indicated above.

I do not mean to sound insensitive about the matter but I'm responding in the context of hard and fast facts.

I live in Brooklyn, 4.5 miles from the former towers. I watched the entirety of the horrific process from my rooftop. Four weeks have since passed and the city is still deep in grief. You can see from the body language of people in the streets that nerves are shot and personalities humbled. Four weeks have since passed and Sept 11 is still the dominant conversation in many meeting places.

One of the few positive repurcussions is that we're not so rude to eachother any longer.


Bodies (4.00 / 1) (#9)
by epepke on Thu Oct 11, 2001 at 04:23:49 PM EST

You are probably right. I got back from there a week and a half ago. There is a serious concern, amongst the asbestos and PVC's, about the long-term effects of constantly inhaling incinerated human bone. There's quite a lot of it in the air, and it's going to be there for a while. The EPA says that it's probably not harmful, but they have no data.

The truth may be out there, but lies are inside your head.--Terry Pratchett

[ Parent ]
Cremation of bodies (4.00 / 1) (#10)
by panner on Thu Oct 11, 2001 at 04:44:01 PM EST

My mom (a registered nurse) works with a woman that's in the Red Cross (also in the Reserves, but I don't think she's been called up). She went to New York just a few days afterwards (she was flown up and back in a military helicoptor), supposedly to help in the hospitals.

However, there was nothing for her or the other volunteers to do, since no one was being found alive. So they were sent out to the scene to assist in rescuse (or do something out there). She said that they weren't finding hardly anything that would you would associate with people. No bodies, parts, or even items like belts. The heat of the fire had cremated everyone on the upper floors.

Keith Smiley
Get it right, for God's sake. Pigs can work out how to use a joystick, and people still can't do this!
[ Parent ]
You are correct (4.00 / 1) (#12)
by theR on Thu Oct 11, 2001 at 05:41:01 PM EST

A lot of people will never have a recognizable part recovered. However, from what I understand, they are still making an attempt. Although it is not being done on site, I was under the impression that the rubble is being removed and sorted through at another location for both evidence and remains. As I said in the story, they are attempting recovery now, which is definitely diffferent from search and rescue. They may not be very successful, but I would assume they will make all reasonable attempts, perhaps beyond what some consider reasonable, to find and identify remains of victims.

I was never trying to give the impression that they are looking for survivors, although maybe I'm misunderstanding your comment.

[ Parent ]
3D Mapping of the WTC Site (4.00 / 1) (#11)
by Nitesurfer on Thu Oct 11, 2001 at 04:56:02 PM EST

Found this interesting news piece that kind of ties in to above story.

A laptop company donated 20 Ultra Rugged units to FEMA and other NY agencies.

Rescue squads will use the laptops to create detailed maps of the entire relief area.

"One will be to create 3-D maps of the debris piles, so theycan assess how much debris they have to remove," said Roush.

See the complete article at " Spokane company's laptops aiding disaster relief "

David Byrd

CEO --- Twenty First Century Technologies, Inc.
Home of the Nite-Surfer Illuminated Keyboard

Strange Sense of Proportion (3.80 / 5) (#15)
by snowlion on Sat Oct 13, 2001 at 06:22:05 AM EST

Even for those who did not know any of the victims, you often do not need to look far to find a friend or relative that did know someone.

50,000 people died last year in US car accidents.

How many people here knew someone who died in a car accident within the last year? Sure, there might be a handful, but really..

You are ten times more likely to know someone who died in a car accident in the last year than you are to know one of the victims.

10,000 people died last year from falling down. As in- tripping and falling down the stairs. You are twice as likely to know someone who died from falling down- in the last year, than you are to know one of the victims.

Do you know anyone who knew anyone who died by falling down last year? I don't!

Let's not blow this thing out of proportion.

Map Your Thoughts
Push... (none / 0) (#16)
by demaratus on Sat Oct 13, 2001 at 08:01:36 PM EST

Yes, but some tool with an overblown sense of self importance did not push those 10,000 people down the stairs....

[ Parent ]
Hey, you never know... (n/t) (none / 0) (#17)
by vectro on Sat Oct 20, 2001 at 08:13:16 PM EST

“The problem with that definition is just that it's bullshit.” -- localroger
[ Parent ]
Science, Technology, and the World Trade Center | 17 comments (13 topical, 4 editorial, 0 hidden)
Display: Sort:


All trademarks and copyrights on this page are owned by their respective companies. The Rest 2000 - Present Kuro5hin.org Inc.
See our legalese page for copyright policies. Please also read our Privacy Policy.
Kuro5hin.org is powered by Free Software, including Apache, Perl, and Linux, The Scoop Engine that runs this site is freely available, under the terms of the GPL.
Need some help? Email help@kuro5hin.org.
My heart's the long stairs.

Powered by Scoop create account | help/FAQ | mission | links | search | IRC | YOU choose the stories!