SEEING THE WORLD
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Well, we’ve done plants and animals and global warming and medicine lately, and now I think it’s time to dip into the technology file to see what weird and wonderful things the technogeeks are up to. So off we go to the Alice in Wonderland world of technology.
Don’t you just love the new cameras and photophones? And the ease of putting all those infinite pictures onto the net for all your friends and families and grandparents and prospective employers and everyone else to see is just wonderful. Unless of course, things get posted that you didn’t want everyone to see. But we won’t get into that here.
Let’s stick to talking about vacation photos and perhaps posting them on Flickr. It turns out lots of folks have done that, and well, read on!
BUILDING ROME IN A DAY
We all know that Rome wasn’t built in a day. It took 10 years to build the Coliseum and almost 100 years to build St. Peter’s Basilica. But researchers at the University of Washington have developed a new computer algorithm that used hundreds of thousands of tourist photos to automatically reconstruct the city of Rome. It took about a day.
The tool is the most recent in a series developed at UW to harness the enormous digital photo collections available on photo-sharing Web sites. The digital Rome was assembled from 150,000 tourist photos tagged with the word "Rome" or "Roma" that were downloaded from the popular photo-sharing Web site, Flickr.
Computers analyzed each image and in 21 hours combined them to create a 3-D digital model. Using this model, a viewer can fly around Rome’s landmarks, from the Trevi Fountain to the Pantheon to the inside of the Sistine Chapel. Earlier versions of the UW photo-stitching technology are known as Photo Tourism. That technology was licensed in 2006 to Microsoft, which now offers it as a free tool called Photosynth.
In addition to Rome, the team recreated the Croatian coastal city of Dubrovnik, processing 60,000 images in less than 23 hours using a cluster of 350 computers, and Venice, Italy, processing 250,000 images in 65 hours using a cluster of 500 computers. Many historians see Venice as a candidate for digital preservation before water does more damage to the city, the researchers said.
Transitioning from landmarks to cities — going from hundreds of photos to hundreds of thousands of photos — is not trivial. Previous versions of the Photo Tourism software matched each photo to every other photo in the set. But as the number of photos increases the number of matches increases exponentially. A set of 250,000 images would take at least a year for 500 computers to process and a million photos would take more than a decade using the previous version.
The newly developed code works more than a hundred times faster than the previous version. It first establishes likely matches and then concentrates on those parts. The code also uses parallel processing techniques, allowing it to run simultaneously on many computers, or even on remote servers connected through the Internet. This new, faster code makes it possible to tackle more ambitious projects.
This technique could create online maps that offer viewers a virtual-reality experience. The software could build cities for video games automatically, instead of doing so by hand. It also might be used in architecture for digital preservation of cities, or integrated with online maps. In the near term, the "Rome in a Day" code could be used with Photo Tourism, Photosynth or other software designed to view the model output.
The research was supported by the National Science Foundation, the Office of Naval Research and its Spawar lab, Microsoft Research, and Google.
The Colosseum as seen in the digital reconstruction. Each triangle is where a person was standing when he or she took a photo (Credit: University of Washington)
So, we’re actually looking at the first step in creating a virtual world without the flies and the heat and the smells. I’m not so sure that’s a really good tradeoff, but then I’ve always had just a whiff of the Luddite about me!
And now we’ll move on to a new controversial technology that’s being put to some uses that aren’t quite so controversial.
SEE THROUGH
We’ve all heard about terahertz radiation or THz. That’s the technology they want to put in airports to cut down on the risk of people smuggling weapons onboard an airplane concealed in their clothing. Terahertz radiation sees right through your clothes and that’s why a lot of people are not happy about being seen au natural at the airport!
It turns out that terhertz radiation has other uses because it can not only see through clothes, it can see through paint. German researchers are using THz to look at old paintings and murals.
Conventional wisdom says that once you paint over a mural, it’s gone because current methods can’t reveal the picture beneath without damaging it. Many church paintings are hidden from sight because they were painted over centuries ago. As tastes and religious fervors changed, walls were painted and repainted many times. In many old churches and other buildings, layers of paintings from various epochs can now be found superimposed on top of each other.
If you strip the paint to the original picture using conventional methods you risk damaging it. You also destroy the layers of pictures above it and they may be worthy of preservation too. So what’s a poor conservationist to do? Use terahertz radiation!
THz radiation can penetrate plaster and lime washes even if the layer is relatively thick. And unlike other radiation wavelengths like ultraviolet, THz radiation doesn’t damage the art. Infrared beams don’t work because they can’t penetrate deep enough and microwaves can’t provide the necessary width and depth resolution.
The German researchers developed a mobile system that can be used anywhere to conduct the examinations. The scanner travels over the wall without touching it and has two measuring heads; one transmits the radiation, the other picks up the reflected beams.
Each layer and each pigment reflects the transmitted pulses differently so that picture contrast as well as depth information can be obtained. The measured results provide information about the thickness of the painted layers, what pigments were used and how the colors are arranged. A specially developed software system puts the measured results together to form a picture displaying the structure of the concealed paintings.
The scientists have already succeeded in revealing the structures of concealed pictures on a test wall where several different pictures were painted and then painted over with other pictures. The next step will be to conduct a practical test in a church.
The mobile scanner at work on a test wall. A software system reveals the structure of the concealed paintings. (Credit: Copyright Fraunhofer IWS)
And now we come to a story that still just blows me away. One of the things I definitely remember from high school science classes were the great strides that had been made in microscopy. It was the beginning of the era of the electron microscope and astounding discoveries were being made everywhere. But there was one boundary that everybody agreed on. No matter how good microscopes got, we would NEVER be able to see individual atoms!
Just goes to show you that ‘never’ is a very tricky word that should probably be avoided in most cases!
SEEING FARTHER
Using the latest in aberration-corrected electron microscopy, researchers at the Department of Energy’s Oak Ridge National Laboratory and their colleagues have obtained the first images that distinguish individual light atoms such as boron, carbon, nitrogen and oxygen. (Yes, boys and girls, they have taken pictures of individual ATOMS).
The ORNL images were obtained with a Z-contrast scanning transmission electron microscope (STEM). Individual atoms of carbon, boron, nitrogen and oxygen–all of which have low atomic numbers–were resolved on a single-layer boron nitride sample.
"This research marks the first instance in which every atom in a significant part of a non-periodic material has been imaged and chemically identified," said Materials Science and Technology Division researcher Stephen Pennycook. "It represents another accomplishment of the combined technologies of Z-contract STEM and aberration correction."
The new high-resolution imaging technique enables materials researchers to analyze, atom by atom, the molecular structure of experimental materials and discern structural defects in those materials. Defects introduced into a material–for example, the placement of an impurity atom or molecule in the material’s structure–are often responsible for the material’s properties.
The group analyzed a monolayer hexagonal boron nitride sample prepared at Oxford University and was able to find and identify three types of atomic substitutions–carbon atoms substituting for boron, carbon substituting for nitrogen and oxygen substituting for nitrogen. Boron, carbon, nitrogen and oxygen have atomic numbers–or Z values– of five, six, seven and eight, respectively.
Armed with the high-resolution images, materials, chemical and nanoscience researchers and theorists can design more accurate computational simulations to predict the behavior of advanced materials, which are key to meeting research challenges that include energy storage and energy efficient technologies. (In other words, if we can actually see what it looks like, we can figure out how it all fits together!)
Individual boron and nitrogen atoms are clearly distinguished by their intensity in this Z-contrast scanning electron transmission microscope image from Oak Ridge National Laboratory. Each single hexagonal ring of the boron-nitrogen structure, for instance the one marked by the green circle in the figure a, consists of three brighter nitrogen atoms and three darker boron atoms. The lower (b) image is corrected for distortion. (Credit: Department of Energy, Oak Ridge National Laboratory)
Seeing a city, seeing a painting, seeing atoms. Our technology is showing us our world, as it’s never been seen before!
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