Again: try reading the article. It's (relatively) easy to generate stereograms from two images taken from slightly different positions. That's been done for decades.
What is non-trivial is generating a stereogram from a single image. In some circumstances only a single image is available and another will never become available. Are you seriously claiming that it's a step backwards to be able to generate a stereogram from a single image?
The research was first applied (AFAIK) to Renaissance oil paintings where, almost by definition, only a single image from a single viewpoint at a single instant in time is available. They managed to produce very convincing 3D models of the scenes and, from them, stereograms.
There are planetary images in existence which are essentially unique. The techniques of Criminisi and Blake allows 3D models and stereograms to be created from those images too.
Try reading further down the page. They are taking a single image and building a steroscopic view. NASA were using pairs of images in the traditional manner.
It was a typo (I assume you refer to the "ours") which slipped past my proo-freading, despite having clicked the Preview button.
Oh well, can't win them all. I think myself lucky if I win any.
Nice to see someone can read mediaeval Italian. Pity you had to give it away to hoi polloi.
Ob-ontopic: The amount of CO_2 in the Martian atmosphere is much higher by percentage terms (about 98%) than in the terrestial atmosphere (about 0.3%) but similar in absolute terms (i.e. partial pressure). It's a bit less on Mars than here, but not enormously so, and most of the discrepancy is accounted for by the solid CO_2 in the polar regions. From this we can conclude that Mars has primarily lost its nitrogen in comparison with the Earth.
It seems like something must be missing from these models.
There is. It's called life. Organisms en mass have two tendencies: to adapt to be comfortable in their environment and to adapt their environment so that it becomes comfortable to them.
Once upon a time, chlorophyll was invented. It converted the plentiful carbon dioxide to plentiful oxygen, leaving a small amount of carbon dioxide behind. Most every other organism takes that oxygen and converts it back to CO2 so that the chlorophyll-containing organisms can recycle it. As the sun has warmed up over geological periods, so has the amount of CO2 decreased and oxygen increased, maintaining a remarkably constant temperature on average.
Ok, a brief tutorial in planetology. Very brief and glosses over much that is presently known. Discovering more is left as an exercise.
While it's true that Venus is closer to the sun than we are, and Mars is further away, that's not the whole truth. Believe it or not, more solar radiation reaches the Earth's surface than ours. The albedo (i.e. reflectivity) of Venus is so high that most sunlight is reflected back out into space before it has a chance to heat the surface. In the case of the Earth, about 50% gets through and about 50% is reflected. The difference in distance between each planet and the sun is not enough to overcome this effect.
An important reason why Mars is so much colder than the Earth is not that it's further away but that it's also much less massive. The martian atmosphere may not be heated as strongly as the terrestial atmosphere, so the atoms and molecules may not move as fast, but they don't have to move as fast to escape and over the aeons they leak away. There are other factors involved, some of them caused or influenced by the lower mass, but this is one of them. Others include the lack of a strong magnetic field (to keep the solar wind at a good distance from heating the upper atmosphere) and, perhaps, the lack of active plate tectonics in recent history.
Turning to Venus, it rotates very slowly and does not have a pernament magnetic field. In its early history it probably had an atmosphere quite like the early Earth's and was very probably at much the same sort of temperature as on the Earth today, but just a bit warmer. Venus was still closer to the sun than was the Earth, but the Sun was noticeably cooler in those days (about 75-80 percent of present luminosity). Not having a magnetic field helped to heat the upper atmosphere; water was photolysed to hydrogen and oxygen and the hydrogen leaked away. At some point in its history, Venus got just a little bit too warm before life had evolved enough to start stabilising the climate as it has done here on Earth for the last few billion years. No-one got around to inventing photosynthesis in a big way to mop up carbon-dioxide and replace it with much less effective (as a greenhouse gas) oxygen while the lack of plate tectonics meant that organic matter and water wasn't safely swept ip into the upper mantle. At least one important feedback mechanism was missing on Venus and the greenhouse effect ran away until we see the conditions today: less solar heating at the surface than the Earth, but a temperature high enough to melt lead.
I think the best place other than an Earth orbit would probably be the moon, though I am just wondering whether the necessary orbit would be too small for proper astronomy (ie moving too much to stay centered on a given subject)?
What's the point of moving it anywhere, given that when the gyros are bust the thing can't be pointed anyway?
They *must* have considered this being smart astronomer people, but if the whole solar system were moving, relative to the star cluster or vice versa then that would have to be taken into account....
Well, some of them are smart and, yes, they have considered this. The technique goes under the name "secular parallax". One minor problem is that not only is the solar system sailing through space, so are all the other stars. By observing the position of many stars over a period of many years it's possible to disentangle the various motions but the statistical averaging involved does tend to reduce the accuracy of the results.
Another of my favorites:
"I before E except after C
and when sounding like A as in neighbor and weigh
or on weekends or holidays or all throughout May
and you'll always be wrong no matter what you say!"
Interesting that you find 'english with brit accent' easy to grasp single words from. I speak english natively and I can barely understand english with a brit accent. (From BC, Canada)
But that's because you speak Canadian and not English. 8-)
My native language is English (I was brought up near Nottingham in the English Midlands) but even so there are some Brits I can barely understand. Glaswegians are notable examples.
Grr! Hit submit by accident part way through. Here's what I'd intended to post
A good analogy here is the architechtural construction techniques of the Egyptian pharaohs. You can build quite big pyramids if you throw a fortune and an army of slaves at the job. But it doesn't scale, it doesn't advance the state of the art, and, crucially, it doesn't get any cheaper when you do it more often. It was the brick-and-mortar commercial construction industry that led via engineering advances to modern skyscraper construction.
I'm not sure you're on very solid ground there.
Back in the good old days, the pharoahs' tombs were low key affairs. Then along came Imhotep, the architect who designed Djoser's pyramid. Imhotep was the guy who really understood what could be done with stone. He realised that it was a really adaptable material with wonderful mechanical properties and a possibility for great aesthetics.
Imhotep undoubtedly advanced the state of the art in the creation of large-scale buildings, and in several other areas too. Ironically, it was the bricks and mortar construction industry that he killed off with his works in stone. Earlier mud-brick pyramids were not very impressive and most have long since crumbled away. The pyramid he designed for his pharaoh is still in reasonably good condition well over 4600 years later.
As for Imhotep, his reputation as a genius survived for well over 2500 years, certainly until the early Christian era. He seemed to be regarded by his successors much as we now look on with awe at Leonardo da Vinci's brilliance. He's known not only as an engineer and architect, but as a physician, poet, astrologer and high-ranking government official.
A good analogy here is the architechtural construction techniques of the Egyptian pharaohs. You can build quite big pyramids if you throw a fortune and an army of slaves at the job. But it doesn't scale, it doesn't advance the state of the art, and, crucially, it doesn't get any cheaper when you do it more often. It was the brick-and-mortar commercial construction industry that led via engineering advances to modern skyscraper construction.
I'm not sure you're on very solid ground there.
Back in the good old days, the pharoahs' tombs were low key affairs. Then along came Imhotep, the architect who designed Djoser's pyramid. Imhotep was the guy who really understood what could be done with stone, that it was a really adaptable material with wonderful mechanical properties and the possbility for great aesthetics.
hypergolic (self igniting) fuels that are pretty much the most dangerous chemicals on earth, after plutonium.
With respect, this is garbage. Plutonium is pretty inoccuous stuff, as long as you don't go around assembling kilogram quantities of it in a small space. Chemically, Pu is about as toxic as lead. People survive for decades with lumps of Pb inside them. Radiologically, Pu is rather feeble too. Its half-life is many thousands of years and, although you wouldn't want to ingest it, there are many other elements that are much nastier. Radium is an obvious example.
I was a chemist in a previous life. I've dealt with chemicals that are markedly nastier than Pu, even in my relatively sheltered life. Elemental fluorine, for instance, and for that matter, azide salts which are either very toxic or detonators or both.
Biologists and biochemists deal with much nastier substances than most chemists.
Hubble.. Compton... Chandra etc. Given that nearly all science probes are named after famous scientists, and clearly no-one got round to nominating one for SIRTF, who does the Slashdot crowd believe this probe should honour?
William Herschel.
He was the first true infra-red astronomer. He used a prism to cast a spectrum of sunlight and then measured the heating effect on the blackened bulb of a mercury thermometer. He was surprised to discover that the heating effect grew greater as he moved towards the red end of the spectrum and greater still for a short way beyond it.
All we have to do now is make a craft that can go 90 light years within a reasonable amount of time. minor detail.
We already have the technology that could get us there in around a couple of thousand years --- and only 1000 if you were happy with a fly-by mission. The 1970s Daedalus study by the BIS showed us how it could be done using only technology known at that time or reasonably expected to be available by the turn of the millenium. To this extent, it is indeed a minor detail.
There are two major details, IMO. The first is cultural: we no longer seem to want to embark on projects that are expected to have payback times measured in centuries, as the builders of the Egyptian pyramids and the European mediaeval cathedrals did.
The other is economic: even if we wanted to do something like this, the cost would be enormous. OTOH, perhaps the cost might be no greater in societal terms than the price to the Egyptian economy almost 5000 years ago of building the great pyramids.
the only thing that is unique about this is the method used to collect data.
The first thing that came to mind when I heard about this project (on BBC radio yesterday) was that it sounded very much like the technique for collecting and identifying bits of comets, paint chips and other hypersonic garbage that's floating around in the inner solar system. Same idea, similar technology, thousand-fold difference in speed, million-fold difference in particle mass.
Not only that, try to explain the infrared coming from some points on the continent. A few points appear to be +20C when the ambient is -40C. Ok, it may be geothermal heat, but worth closer investigation anyway.
I'm not sure whether we could pick up the moving IR sources from orbit using the kind of technology we've put into orbit around Mars. If we could, they would be very interesting.
Visit Antarctica and see how easy it is to detect life at random points on the continent. Feel free to do it as we have done on Mars - by dropping one life-oriented chemical test on a random point, and by taking pictures from orbit.
Dead easy. Observe free oxygen in the atmosphere over Antarctica. Observe methane in the atmosphere over Antarctica. Attempt to propose a mechanism to explain something which is far from chemical equilibrium, given the ample supply of UV radiation hitting the atmosphere.
That's a classical test. Admittedly, it primarily detects the effects of life elsewhere on the planet but it still works even if you observer only Antarctica.
There are other tests that focus specifically on Antarctic life. For instance, try to explain the strange electromagnetic radiation coming from some parts of the continent.
Swim? I thought we were the only primates who canâ(TM)t swim instinctively. We have to be taught. Then again, I could be wrong.
I believe you are semi-wrong. Very young infants can certainly swim instinctively. At around 18 months old they seem to have an instinctive fear of water (unless, of course, they've been encouraged to swim for the previous year or so). It's been suggested that this fear is a survival characteristic, in that you are much less likely to be eaten by crocodiles (probably) or sharks (possibly) if you don't go swimming.
Slashdot Mirror
You don't need so much mass to keep a thick atmosphere that far out in the solar system.
Paul
What is non-trivial is generating a stereogram from a single image. In some circumstances only a single image is available and another will never become available. Are you seriously claiming that it's a step backwards to be able to generate a stereogram from a single image?
The research was first applied (AFAIK) to Renaissance oil paintings where, almost by definition, only a single image from a single viewpoint at a single instant in time is available. They managed to produce very convincing 3D models of the scenes and, from them, stereograms.
There are planetary images in existence which are essentially unique. The techniques of Criminisi and Blake allows 3D models and stereograms to be created from those images too.
Paul
Paul
Oh well, can't win them all. I think myself lucky if I win any.
Nice to see someone can read mediaeval Italian. Pity you had to give it away to hoi polloi.
Ob-ontopic: The amount of CO_2 in the Martian atmosphere is much higher by percentage terms (about 98%) than in the terrestial atmosphere (about 0.3%) but similar in absolute terms (i.e. partial pressure). It's a bit less on Mars than here, but not enormously so, and most of the discrepancy is accounted for by the solid CO_2 in the polar regions. From this we can conclude that Mars has primarily lost its nitrogen in comparison with the Earth.
Paul
There is. It's called life. Organisms en mass have two tendencies: to adapt to be comfortable in their environment and to adapt their environment so that it becomes comfortable to them.
Once upon a time, chlorophyll was invented. It converted the plentiful carbon dioxide to plentiful oxygen, leaving a small amount of carbon dioxide behind. Most every other organism takes that oxygen and converts it back to CO2 so that the chlorophyll-containing organisms can recycle it. As the sun has warmed up over geological periods, so has the amount of CO2 decreased and oxygen increased, maintaining a remarkably constant temperature on average.
Paul
While it's true that Venus is closer to the sun than we are, and Mars is further away, that's not the whole truth. Believe it or not, more solar radiation reaches the Earth's surface than ours. The albedo (i.e. reflectivity) of Venus is so high that most sunlight is reflected back out into space before it has a chance to heat the surface. In the case of the Earth, about 50% gets through and about 50% is reflected. The difference in distance between each planet and the sun is not enough to overcome this effect.
An important reason why Mars is so much colder than the Earth is not that it's further away but that it's also much less massive. The martian atmosphere may not be heated as strongly as the terrestial atmosphere, so the atoms and molecules may not move as fast, but they don't have to move as fast to escape and over the aeons they leak away. There are other factors involved, some of them caused or influenced by the lower mass, but this is one of them. Others include the lack of a strong magnetic field (to keep the solar wind at a good distance from heating the upper atmosphere) and, perhaps, the lack of active plate tectonics in recent history.
Turning to Venus, it rotates very slowly and does not have a pernament magnetic field. In its early history it probably had an atmosphere quite like the early Earth's and was very probably at much the same sort of temperature as on the Earth today, but just a bit warmer. Venus was still closer to the sun than was the Earth, but the Sun was noticeably cooler in those days (about 75-80 percent of present luminosity). Not having a magnetic field helped to heat the upper atmosphere; water was photolysed to hydrogen and oxygen and the hydrogen leaked away. At some point in its history, Venus got just a little bit too warm before life had evolved enough to start stabilising the climate as it has done here on Earth for the last few billion years. No-one got around to inventing photosynthesis in a big way to mop up carbon-dioxide and replace it with much less effective (as a greenhouse gas) oxygen while the lack of plate tectonics meant that organic matter and water wasn't safely swept ip into the upper mantle. At least one important feedback mechanism was missing on Venus and the greenhouse effect ran away until we see the conditions today: less solar heating at the surface than the Earth, but a temperature high enough to melt lead.
Paul
Paul
What's the point of moving it anywhere, given that when the gyros are bust the thing can't be pointed anyway?
Paul
Well, some of them are smart and, yes, they have considered this. The technique goes under the name "secular parallax". One minor problem is that not only is the solar system sailing through space, so are all the other stars. By observing the position of many stars over a period of many years it's possible to disentangle the various motions but the statistical averaging involved does tend to reduce the accuracy of the results.
Paul
Paul
Seize weird Keith?
Paul
But that's because you speak Canadian and not English. 8-)
My native language is English (I was brought up near Nottingham in the English Midlands) but even so there are some Brits I can barely understand. Glaswegians are notable examples.
Paul
A good analogy here is the architechtural construction techniques of the Egyptian pharaohs. You can build quite big pyramids if you throw a fortune and an army of slaves at the job. But it doesn't scale, it doesn't advance the state of the art, and, crucially, it doesn't get any cheaper when you do it more often. It was the brick-and-mortar commercial construction industry that led via engineering advances to modern skyscraper construction.
I'm not sure you're on very solid ground there.
Back in the good old days, the pharoahs' tombs were low key affairs. Then along came Imhotep, the architect who designed Djoser's pyramid. Imhotep was the guy who really understood what could be done with stone. He realised that it was a really adaptable material with wonderful mechanical properties and a possibility for great aesthetics.
Imhotep undoubtedly advanced the state of the art in the creation of large-scale buildings, and in several other areas too. Ironically, it was the bricks and mortar construction industry that he killed off with his works in stone. Earlier mud-brick pyramids were not very impressive and most have long since crumbled away. The pyramid he designed for his pharaoh is still in reasonably good condition well over 4600 years later.
As for Imhotep, his reputation as a genius survived for well over 2500 years, certainly until the early Christian era. He seemed to be regarded by his successors much as we now look on with awe at Leonardo da Vinci's brilliance. He's known not only as an engineer and architect, but as a physician, poet, astrologer and high-ranking government official.
Here's a nice intro to Imhotep and here can be found more detail on the pyramid he designed.
Paul
I'm not sure you're on very solid ground there.
Back in the good old days, the pharoahs' tombs were low key affairs. Then along came Imhotep, the architect who designed Djoser's pyramid. Imhotep was the guy who really understood what could be done with stone, that it was a really adaptable material with wonderful mechanical properties and the possbility for great aesthetics.
Perhaps you have misunderstood the difference between a subpoena and a request for a comment.
Paul
It's a pity Mendeleevium has such a short half-life, or you could try the experiment and see if it works even better than Manganese.
Paul
Europe?
Japan?
China?
India?
Paul
With respect, this is garbage. Plutonium is pretty inoccuous stuff, as long as you don't go around assembling kilogram quantities of it in a small space. Chemically, Pu is about as toxic as lead. People survive for decades with lumps of Pb inside them. Radiologically, Pu is rather feeble too. Its half-life is many thousands of years and, although you wouldn't want to ingest it, there are many other elements that are much nastier. Radium is an obvious example.
I was a chemist in a previous life. I've dealt with chemicals that are markedly nastier than Pu, even in my relatively sheltered life. Elemental fluorine, for instance, and for that matter, azide salts which are either very toxic or detonators or both.
Biologists and biochemists deal with much nastier substances than most chemists.
Paul
William Herschel.
He was the first true infra-red astronomer. He used a prism to cast a spectrum of sunlight and then measured the heating effect on the blackened bulb of a mercury thermometer. He was surprised to discover that the heating effect grew greater as he moved towards the red end of the spectrum and greater still for a short way beyond it.
Paul
Neither is it the same number. Last time I looked, the most significant digit of 7e22 is 7 and the MSD of 60 sextillion is 6.
Paul
We already have the technology that could get us there in around a couple of thousand years --- and only 1000 if you were happy with a fly-by mission. The 1970s Daedalus study by the BIS showed us how it could be done using only technology known at that time or reasonably expected to be available by the turn of the millenium. To this extent, it is indeed a minor detail.
There are two major details, IMO. The first is cultural: we no longer seem to want to embark on projects that are expected to have payback times measured in centuries, as the builders of the Egyptian pyramids and the European mediaeval cathedrals did. The other is economic: even if we wanted to do something like this, the cost would be enormous. OTOH, perhaps the cost might be no greater in societal terms than the price to the Egyptian economy almost 5000 years ago of building the great pyramids.
Paul
The first thing that came to mind when I heard about this project (on BBC radio yesterday) was that it sounded very much like the technique for collecting and identifying bits of comets, paint chips and other hypersonic garbage that's floating around in the inner solar system. Same idea, similar technology, thousand-fold difference in speed, million-fold difference in particle mass.
Paul
Not only that, try to explain the infrared coming from some points on the continent. A few points appear to be +20C when the ambient is -40C. Ok, it may be geothermal heat, but worth closer investigation anyway.
I'm not sure whether we could pick up the moving IR sources from orbit using the kind of technology we've put into orbit around Mars. If we could, they would be very interesting.
Paul
Dead easy. Observe free oxygen in the atmosphere over Antarctica. Observe methane in the atmosphere over Antarctica. Attempt to propose a mechanism to explain something which is far from chemical equilibrium, given the ample supply of UV radiation hitting the atmosphere.
That's a classical test. Admittedly, it primarily detects the effects of life elsewhere on the planet but it still works even if you observer only Antarctica.
There are other tests that focus specifically on Antarctic life. For instance, try to explain the strange electromagnetic radiation coming from some parts of the continent.
Paul
I believe you are semi-wrong. Very young infants can certainly swim instinctively. At around 18 months old they seem to have an instinctive fear of water (unless, of course, they've been encouraged to swim for the previous year or so). It's been suggested that this fear is a survival characteristic, in that you are much less likely to be eaten by crocodiles (probably) or sharks (possibly) if you don't go swimming.
Paul