First you can check out How Things Work for the basics.
Second, off the shelf imaging devices are challenging to use for scientific data collection for a number of reasons. The main one being their response is usually designed to replicate the human eye rather than a true spectral response--the difference between photometry and radiometry.
For resolution tests, go to www edmundoptics com and check out the various testing targets available. The cheapest mylar USAF targets are pretty good for testing spatial resolution. Remember that when you get close to the resolution limit of the CCD, aliasing due to misalignment is going to be a factor. Your resolution could be up to a factor of 2X (per axis) better than you can test for, unless you're able to align the target with the pixels.
You should also try to figure out which CCD the device uses. Yahoo!'s Electronics Marketplace is a good place to search for components and there is usally a link to the manufacuter's spec sheet. Some spec sheets are quite detailed and will give you plenty of information regarding sensitivity, dark current, spectral response, etc.
Be skeptical of resolution claims. A flatbed scanner I have claims 9600 dpi or about 2.6e-6 m resolution. In reality, it's no better than about 5e-5 m.
Also, the picture you get out vs the "real" picture is highly dependent on the imager's software & firmware. Autoexposure and color correction functions are usually present and can play havoc with an attempt to figure out what the "real" image is. Again, test targets may help here--if you can control all the other variables in the system, you can do some calibration experiments to figure out what the imager is doing to your image.
Well, I hope this points you in the right direction.
NEW YORK, Sept. 11 -- Two aircraft slammed into the World Trade Center in New York on Tuesday, in what was immediately speculated to be a terrorist attack. The FBI reported that a hijacking might have taken place just before the crashes. Police and ambulances were rushing to the scene.
THE AIRCRAFT struck about a half hour apart, starting fires and sending smoke billowing out of the skyscrapers. The first crash happened shortly before 9 a.m. ET.
MSNBC.com reporter Martin Wolk, who was inside one of the towers, said the lights flickered and then a loud bang was heard. People panicked and started to flee the building.
When they reached the lobby, smoke started to fill the building and people could see debris falling and many cars outside were damaged. "It was sheer pandemonium, people were screaming and crying, afraid to go outside because of the falling debris," Wolk said. "We looked up and it looked like the top 20 floors were in flames."
Another bystander described a barrage of debris raining down on the sidewalk below. About 9 a.m., a second aircraft was seen crashing into the other tower. Broadcast cameras already watching the scene filmed the second plane ram the tower.
Large holes were visible in sides of the 110-story buildings. The tops of the twin towers were obscured by the smoke.
Thousands of pieces of what appeared to be office paper came drifting over Brooklyn, about three miles from the tower, one witness said.
A video freeze shows a plane just before it hits the center some 18 minutes after the first crash.
Terrorism was speculated given that the center was bombed on Feb. 26, 1993, killing six people and injured more than 1,000 others.
The FBI said it was investigating reports of a hijacking. A United Airlines employee said he had heard reports that an American Airlines jet had been hijacked and was one of the two aircraft that flew into the center. It was not clear if there were passengers on board.
New York airports and the Lincoln Tunnel reportedly were closed as a precautionary measure.
Good point. What's really missing in all these references to public places and "reasonable expectations of privacy" is a distinction between what is possible and what may be reasonably expected in a civilized society. Sure, in Grand Central Station, a person unknown to you could follow you around, make copius observations of your behavior, and solicit/harass you for your money. However, most people would regard this as fucking rude, if not harassing; and as NY has shown, when the harassers are of sufficiently low social status, the state is more than happy to give them the bums' rush.
One may not have a reasonable expectation of total privacy in a public place, but surely one may have a reasonable expectation of not being under a goddamn microcope either.
Slashdot Mirror
First you can check out How Things Work for the basics.
Second, off the shelf imaging devices are challenging to use for scientific data collection for a number of reasons. The main one being their response is usually designed to replicate the human eye rather than a true spectral response--the difference between photometry and radiometry.
For resolution tests, go to www edmundoptics com and check out the various testing targets available. The cheapest mylar USAF targets are pretty good for testing spatial resolution. Remember that when you get close to the resolution limit of the CCD, aliasing due to misalignment is going to be a factor. Your resolution could be up to a factor of 2X (per axis) better than you can test for, unless you're able to align the target with the pixels.
You should also try to figure out which CCD the device uses. Yahoo!'s Electronics Marketplace is a good place to search for components and there is usally a link to the manufacuter's spec sheet. Some spec sheets are quite detailed and will give you plenty of information regarding sensitivity, dark current, spectral response, etc.
Be skeptical of resolution claims. A flatbed scanner I have claims 9600 dpi or about 2.6e-6 m resolution. In reality, it's no better than about 5e-5 m.
Also, the picture you get out vs the "real" picture is highly dependent on the imager's software & firmware. Autoexposure and color correction functions are usually present and can play havoc with an attempt to figure out what the "real" image is. Again, test targets may help here--if you can control all the other variables in the system, you can do some calibration experiments to figure out what the imager is doing to your image.
Well, I hope this points you in the right direction.
Planes slam into World Trade Center
MSNBC STAFF AND WIRE REPORTS
NEW YORK, Sept. 11 -- Two aircraft slammed into the World Trade Center in New York on Tuesday, in what was immediately speculated to be a terrorist attack. The FBI reported that a hijacking might have taken place just before the crashes. Police and ambulances were rushing to the scene.
THE AIRCRAFT struck about a half hour apart, starting fires and sending smoke billowing out of the skyscrapers. The first crash happened shortly before 9 a.m. ET.
MSNBC.com reporter Martin Wolk, who was inside one of the towers, said the lights flickered and then a loud bang was heard. People panicked and started to flee the building.
When they reached the lobby, smoke started to fill the building and people could see debris falling and many cars outside were damaged. "It was sheer pandemonium, people were screaming and crying, afraid to go outside because of the falling debris," Wolk said. "We looked up and it looked like the top 20 floors were in flames."
Another bystander described a barrage of debris raining down on the sidewalk below. About 9 a.m., a second aircraft was seen crashing into the other tower. Broadcast cameras already watching the scene filmed the second plane ram the tower.
Large holes were visible in sides of the 110-story buildings. The tops of the twin towers were obscured by the smoke.
Thousands of pieces of what appeared to be office paper came drifting over Brooklyn, about three miles from the tower, one witness said.
A video freeze shows a plane just before it hits the center some 18 minutes after the first crash.
Terrorism was speculated given that the center was bombed on Feb. 26, 1993, killing six people and injured more than 1,000 others.
The FBI said it was investigating reports of a hijacking. A United Airlines employee said he had heard reports that an American Airlines jet had been hijacked and was one of the two aircraft that flew into the center. It was not clear if there were passengers on board.
New York airports and the Lincoln Tunnel reportedly were closed as a precautionary measure.
This is a breaking story and will be updated.
The Associated Press contributed to this report.
Good point. What's really missing in all these references to public places and "reasonable expectations of privacy" is a distinction between what is possible and what may be reasonably expected in a civilized society. Sure, in Grand Central Station, a person unknown to you could follow you around, make copius observations of your behavior, and solicit/harass you for your money. However, most people would regard this as fucking rude, if not harassing; and as NY has shown, when the harassers are of sufficiently low social status, the state is more than happy to give them the bums' rush.
One may not have a reasonable expectation of total privacy in a public place, but surely one may have a reasonable expectation of not being under a goddamn microcope either.
"Not quite the fast, cheap and out-of-control solution... "
No, that would be fat, gassy, and out of control.
Head for the hills, little green men.