500 megapixels for $1600 versus scanning-back cameras that cost tens of thousands. Make the error correction a little bit simpler by rotating the scanning back ninety degrees for four 4-color shots (16 exposures), overlaying them, and taking the median pixel values, at the expense of some resolution.
There are four considerable challenges here, though, not just one, and this project could stall on any of them: Image capture Projection determination & georeferencing Digitizing features & establishing topology Geocoding
Add bounties for features & bugs that your organization needs, or alternately if you'd like to improve the product just increase existing bounties you find by a set %.
This brings up a disturbing and topical image.
Blanket octopi are known for using tools already. And they're not just hermit crab level shelters. They tear the living jelly tentacles off of Portuguese Man-O-War colonies, and carry them around stinging any predator that becomes bothersome.
Outright public acceptance of something like amakudari is present in the US, but only in the DC area. In one form or another, corruption sustains this town - if "corporate lobbying" lost constitutional protection, or civil servants/former politicians/their family were banned from being paid for it, our economy would collapse. The defense department, which has a spectacular number of 'promote or retire' thresholds, is particularly subject to the revolving door phenomena, but we have several thousand positions of political power at any given time which are subject to it.
How many people listen to music they've downloaded, vs read books they've downloaded? How willing are people to stockpile books they might want to read, versus music they might want to listen to?
I have a friend with more books on his hard drive than my county library system has on their shelves. In case he ever wants to read them. In case of nuclear war. In case of anything. He finds that about half of my new-read requests are fulfilled on the internet, via simple torrent sites which are 1-step removed from the usenet and IRC scene. Surprisingly, this hasn't affected his buying habits.
He told me to start with the Great Science Textbooks 2007 DVD library, which comes in 20 parts (the final one was a few months ago, when the Knowledge-Should-Be-Free-based releaser considered his quest finished and stopped compiling), and covers a lot more than physics and biology. Supplement that with a few science fiction library dumps, some programming stuff in areas you're interested in, and you're golden to read until you die.
First, they graded people based on physical capabilities - who runs the fastest. This had the effect of failing the fat kid.
Then, they graded them based on personal achievement - who has improved their running times the most. This had the effect of failing someone who put in their full effort the first time.
Then, they graded them based on stamina - who made it through the full two miles. This had the effect of failing whoever had the least muscle mass and most weight to carry - again, the fat kid.
Now, their idea may be to grade them based on who raises their heart rate to a specified level - the idea being that this is a more even distribution of effort even if it takes the athletic kid five times as much distance as the fat kid.
Personally, I don't see why we need to grade a bloody PE class.
Actually, not counting the light solar, chemical, and thermal wear that roads suffer, the main process of mechanical road wear is proportional to the fourth power of axle weight. Most residential streets would need no maintenance whatsoever if it weren't for heavy school buses, trash trucks, and delivery vehicles.
Those heavy vehicles happen to chug gasoline or diesel.
To be a fuel efficient passenger vehicle, a requisite condition is a light body and a low axle weight. They contribute virtually nothing to road wear. We can't justify a usage fee on bicycles or pedestrians for using the pavement - and we can't justify a per-mile fee that hits a Prius just as much as an F-350.
Evolution includes natural selection and artificial selection. It includes anything that affects the movement of genes through the gene pool from one generation to the next. It is by no means restricted to genetic changes which make an animal reproductively incompatible with a group of its recent ancestors you choose to call a "species". Such distinctions are largely arbitrary, but even if you choose to be straitjacketed by Linnaeun orthodoxy and pinpoint a precise point when one species becomes another, you need some term to explain how genes are selected for within a species. Most of us choose to use "evolution".
Do you honestly expect us to believe that somebody suddenly thought - "I know, I'll make an entirely new unnecessary distribution system for disk menus, we'll store them on a central server, and this will improve the user experience!"
You don't "overlook a design mistake" this elaborate, you design it deliberately with some other goal in mind. The only reasonable goal here would be to remove ownership of the menus from the consumer, in order to restrict them to DRM-approved disks. It was entirely intentional.
While everyone can agree that accurate, precise localized predictions are never going to emanate from the Climatology department...
You exaggerate your case severely.
The short-term anthropogenic global cooling scare barely rose above the level of rumor. If not for a "spectacularly wrong" (their words, in the retraction) sensationalist Newsweek article, and the well-funded opposition to the consensus on "Global Warming" picking at whatever they can get, this scientific misadventure would be remembered only by the handful of scientists that thought to spice their papers up with exclamation points and unsupported, untestable prophecy. Most scholarly examinations of the topic remained sober about the geological timespans involved.
Noone was seriously attempting to affect change in the world using this as a support. It never approached consensus in the scientific community, for good reason. You can't use the viewpoint that "man is simply too immature to be allowed to speculate on climate based on yesterday's weather" when we have working physical models of the greenhouse effect that an elementary school student can construct, *steadily* rising CO2 concentrations, highly-corresponding explanations from the paleoclimatologists, and horrific computer models ON TOP of the weather.
You can debate the feedback effects, but the best-case scenario that remains a reasonable expectation if we continue business as usual(and CO2 keeps rising at its current pace) is the level that scientific and popular consensus is perched on. The worst case scenarios are rarely talked about, because they're so divergant and lack human-scale endpoints - but they generally involve massive changes to the landscape through drought, flooding, heating, cooling, et cetera, in the short term.
You're talking about (to a small angle approximation for the popular geosynchronous orbit) pushing a broom across 8.625 billion square miles. Take into account three dimensions in order to sweep a range of orbits and uncertainty and non-circular orbits....
You would never be able to remove as much debris as you added through malfunctions, fuel discharge, maneuvering jets, et cetera.
It's *extremely* messy cleaning up after a security screwup like this.
One day, Hostgator decided that they'd grown to the point that they were likely to have at least one disgruntled ex-employee - and one was under suspicion given his behavior at a later job. All employees had access to the plaintext passwords of all customers. So they decided to email every customer something that looked identical to a phishing scam, instructing them to click the link and change their password if they ever wanted to access their account again. Then, they made a random alphanumeric password generator, and put a filter so that the user couldn't create a password using common english words. Then, they cut everybody off from their accounts - resellers, dedicated servers, everybody.
Hostgator was considered one of the best of the independent budget webhosts up to this point. After the crisis died down, I suspect they lost a significant fraction of the business they'd acquired in six years of operation over the course of a week. A publicly traded company which is heavily leveraged would have completely folded if a third of their customers dried up overnight... which should scare you. Hostgator was honest and publicly, rightly paranoid about its problems, and if they could have handled it a lot better(pushing passwords downstream automatically, for example), you have to wonder how often large businesses are simply ignoring this kind of thing as operational and career suicide.
There are all sorts of schemes you can use for energy storage, but the simplest in most of the US, for another several years of massive growth, is to just shift the existing hydroelectric turbines down a bit in their ratio of baseload generation to on-demand peak-filling generation.
The drilling of the forbidden regions of the OCS in general is bad because they don't have enough oil to compensate for the risks & publicity, and the drilling off these other coasts *now* is bad because we're still near peak oil consumption, wasting oil at a breathtaking rate & struggling to develop renewables. A better geological survey is probably a wise move, but it should not be a prelude to drilling - yet.
A renewable infrastructure for the country is a difficult thing to develop after the tens of trillion we've sunk into fossil fuels - and a palliative can be a dangerous thing. The low oil prices of the 80's and 90's destroyed most of the conservation efforts of the 70's (not to mention the independant US oil industry), and all indications are that there is no rainbow on the other side of the current storm.
Venezuela, Russia, and Saudi Arabia will be polluted, because Peak Oil is an inevitable global phenomenon with global effects - responsibility be damned. We can choose to put all our efforts into shifting away from oil, or we can choose to make the precipice of oil depletion steeper but farther away by burning everything we have, emptying the SPR, and subsidizing fuel & road construction for a few more years.
Alternately, we can undertake to create the biggest environmental catastrophe possible, and attempt to make coal to liquids, tar sands, and tar shales the standard fuel of the future.
A faster option (if you're satisfied with the resolution) would be to do this with a dozen Polaroids at a time, and chop them up using scripts.
There are a lot of photographic details you need to pay attention to here, and external flash isn't necessarily one of them (certainly not the only one).
There are ways to measure population density... and then there are ways to measure population density. Both Canada and Australia have vast plots of mostly empty territory, and most of the population huddled into relatively concentrated cities.
Something along the lines of "Mean number of people within 1km of each household" seems like it deserves a complementary place alongside raw population density.
Australia has less than 1/100th the population density of Japan - but the average Australian doesn't live in a wasteland, he lives in a place that the government designates as "urban" - along with 93% of his countrymen. In Japan, only 66% of the population is designated as living in an urban area.
Speaking very, very generally, the broader spectrum and the higher dose the poison (whatever the poison - animal, vegetable, or mineral), the more difficult it is for a population to evolve resistance against it. Bleach kills almost everything - it's a broad-spectrum disinfectant precisely because organisms have found such difficulty in evolving defenses against a bleachy environment. A very narrow-spectrum poison, perhaps a bioengineered virus which targets a single strand of DNA present in 20% of the population for its high lethality, quickly finds itself going up against organisms which are resistant to its spread. In a generation or two, most of those organisms are dead or have developed antibodies against it, or, in many creatures, have inherited antibodies against it from their mothers. The population routes around the problem, because avoiding that strand of DNA is necessary for survival. Against a wider spectrum poison like high temperatures, a hugely unlikely, very complicated system of heat disposal might be required for any of the population to survive.
UV tolerance is relatively easy in human beings (it's been estimated that a thousand years in a different environment is enough to change a population's skin color entirely, from opposing evolutionary pressures involving essential nutrients dark skin can't make, and essential nutrients sunburnt, dead skin can't make), but only because we as large multicellular animals have evolved multiple redundant structures to deal with it - fur/hair, thick layers of dead skin on back and shoulders, variable melanin production adjustable by multiple genes, external means like clothes, houses, hats, and forest canopies, and even short-term adaptations like temporary melanin production during tanning.
Re: The DelMarVa coast - It's warm enough, breezy enough, and wet enough to approximate a beach in summer. With cheap oil, it's a cheap automotive vacation. It attracts everyone east of Appalachia, south of Pennsylvania, and north of Richmond. Somehow it never became an icon - but it is the most popular vacation destination for several million people.
The only inhabitants that aren't supported by the corporate technicalities or the vacation industry are farmers.
The only real increase in household income the bottom 80% of earning households has seen in the last fourty years is from the rise in two-career households.
So take all that you mentioned, and add in a spouse who must do the same thing.
Chalk up spiralling gas, healthcare, and food prices, a popped housing bubble, a weakening dollar, and it becomes rather difficult for all but the rich to survive, economically.
Then you begin to see the situation we're in, and part of the reason the whole political spectrum is moving left - including the preexisting progressives.
Central & west Africa Russian and northeastern Europe Bangkok Hong Kong Shanghai The entire east coast of South America Florida Seoul Cape Town
Even so, it's not about using locations where earthquakes don't happen at all, it's about avoiding tunnelling through faultlines. A little vibration isn't going to destroy things.
Average high in LA in July: 84 Average low in LA in December: 50 Annual average precipitation in LA: 14 inches
Average high in Vegas in July: 104.1 Average low in Vegas in December: 36.6 Annual average precipitation in Vegas: 4.5 inches
The reason Vegas gets criticized more than other desert cities is that it sells itself as a place without a culture, an artificial paradise without the need for traditional morals, where you don't have to worry about anything... and it bathes in that sentiment. How long could a single fake venetian canal support the people of the city? The place has quadrupled in size in the last generation - a boomtown where the sole resource is the trivial lack of a few moralizing inhibitions.
All of the desert cities are threatened as the water and the fossil fuels run out, but Vegas is at the pinnacle of unsustainability - its population would flee if given a few libertarian governors in other states, or a single dam failure, or a continuation of the last decade's draught, or a significant decrease in the Colorado River's flow due to water usage upstream, or a major recession, or a few years of $5-$10/gallon gasoline, or a dozen other things.
Re:fuel costs still not high enough priority
on
Big Rigs Go High Tech
·
· Score: 3, Insightful
That's because since WW2, we've spent a hundred billion dollars a year constructing, expanding, and maintaining the roads, and ten million dollars a year tearing up rails so that people wouldn't trip over them.
Slashdot Mirror
http://www.cs.ubc.ca/~heidrich/Papers/EG.04.pdf
"Design of an Inexpensive Very High Resolution Scan Camera System".
500 megapixels for $1600 versus scanning-back cameras that cost tens of thousands. Make the error correction a little bit simpler by rotating the scanning back ninety degrees for four 4-color shots (16 exposures), overlaying them, and taking the median pixel values, at the expense of some resolution.
There are four considerable challenges here, though, not just one, and this project could stall on any of them:
Image capture
Projection determination & georeferencing
Digitizing features & establishing topology
Geocoding
This is the most relevant comment I've seen.
Add bounties for features & bugs that your organization needs, or alternately if you'd like to improve the product just increase existing bounties you find by a set %.
This brings up a disturbing and topical image. Blanket octopi are known for using tools already. And they're not just hermit crab level shelters. They tear the living jelly tentacles off of Portuguese Man-O-War colonies, and carry them around stinging any predator that becomes bothersome.
Outright public acceptance of something like amakudari is present in the US, but only in the DC area. In one form or another, corruption sustains this town - if "corporate lobbying" lost constitutional protection, or civil servants/former politicians/their family were banned from being paid for it, our economy would collapse. The defense department, which has a spectacular number of 'promote or retire' thresholds, is particularly subject to the revolving door phenomena, but we have several thousand positions of political power at any given time which are subject to it.
Books are usually around 1Mb.
How many people listen to music they've downloaded, vs read books they've downloaded? How willing are people to stockpile books they might want to read, versus music they might want to listen to?
I have a friend with more books on his hard drive than my county library system has on their shelves. In case he ever wants to read them. In case of nuclear war. In case of anything. He finds that about half of my new-read requests are fulfilled on the internet, via simple torrent sites which are 1-step removed from the usenet and IRC scene. Surprisingly, this hasn't affected his buying habits.
He told me to start with the Great Science Textbooks 2007 DVD library, which comes in 20 parts (the final one was a few months ago, when the Knowledge-Should-Be-Free-based releaser considered his quest finished and stopped compiling), and covers a lot more than physics and biology. Supplement that with a few science fiction library dumps, some programming stuff in areas you're interested in, and you're golden to read until you die.
Oh, and get Calibre.
First, they graded people based on physical capabilities - who runs the fastest. This had the effect of failing the fat kid.
Then, they graded them based on personal achievement - who has improved their running times the most. This had the effect of failing someone who put in their full effort the first time.
Then, they graded them based on stamina - who made it through the full two miles. This had the effect of failing whoever had the least muscle mass and most weight to carry - again, the fat kid.
Now, their idea may be to grade them based on who raises their heart rate to a specified level - the idea being that this is a more even distribution of effort even if it takes the athletic kid five times as much distance as the fat kid.
Personally, I don't see why we need to grade a bloody PE class.
It's apparently a more common concept than one would imagine.
I've heard two people who personally knew someone that did it, and three novels that inserted the situation.
O Rly?
Actually, not counting the light solar, chemical, and thermal wear that roads suffer, the main process of mechanical road wear is proportional to the fourth power of axle weight. Most residential streets would need no maintenance whatsoever if it weren't for heavy school buses, trash trucks, and delivery vehicles.
Those heavy vehicles happen to chug gasoline or diesel.
To be a fuel efficient passenger vehicle, a requisite condition is a light body and a low axle weight. They contribute virtually nothing to road wear. We can't justify a usage fee on bicycles or pedestrians for using the pavement - and we can't justify a per-mile fee that hits a Prius just as much as an F-350.
Evolution includes natural selection and artificial selection. It includes anything that affects the movement of genes through the gene pool from one generation to the next. It is by no means restricted to genetic changes which make an animal reproductively incompatible with a group of its recent ancestors you choose to call a "species". Such distinctions are largely arbitrary, but even if you choose to be straitjacketed by Linnaeun orthodoxy and pinpoint a precise point when one species becomes another, you need some term to explain how genes are selected for within a species. Most of us choose to use "evolution".
Do you honestly expect us to believe that somebody suddenly thought - "I know, I'll make an entirely new unnecessary distribution system for disk menus, we'll store them on a central server, and this will improve the user experience!"
You don't "overlook a design mistake" this elaborate, you design it deliberately with some other goal in mind. The only reasonable goal here would be to remove ownership of the menus from the consumer, in order to restrict them to DRM-approved disks. It was entirely intentional.
While everyone can agree that accurate, precise localized predictions are never going to emanate from the Climatology department...
You exaggerate your case severely.
The short-term anthropogenic global cooling scare barely rose above the level of rumor. If not for a "spectacularly wrong" (their words, in the retraction) sensationalist Newsweek article, and the well-funded opposition to the consensus on "Global Warming" picking at whatever they can get, this scientific misadventure would be remembered only by the handful of scientists that thought to spice their papers up with exclamation points and unsupported, untestable prophecy. Most scholarly examinations of the topic remained sober about the geological timespans involved.
Noone was seriously attempting to affect change in the world using this as a support. It never approached consensus in the scientific community, for good reason. You can't use the viewpoint that "man is simply too immature to be allowed to speculate on climate based on yesterday's weather" when we have working physical models of the greenhouse effect that an elementary school student can construct, *steadily* rising CO2 concentrations, highly-corresponding explanations from the paleoclimatologists, and horrific computer models ON TOP of the weather.
You can debate the feedback effects, but the best-case scenario that remains a reasonable expectation if we continue business as usual(and CO2 keeps rising at its current pace) is the level that scientific and popular consensus is perched on. The worst case scenarios are rarely talked about, because they're so divergant and lack human-scale endpoints - but they generally involve massive changes to the landscape through drought, flooding, heating, cooling, et cetera, in the short term.
You're talking about (to a small angle approximation for the popular geosynchronous orbit) pushing a broom across 8.625 billion square miles. Take into account three dimensions in order to sweep a range of orbits and uncertainty and non-circular orbits....
You would never be able to remove as much debris as you added through malfunctions, fuel discharge, maneuvering jets, et cetera.
It's *extremely* messy cleaning up after a security screwup like this.
One day, Hostgator decided that they'd grown to the point that they were likely to have at least one disgruntled ex-employee - and one was under suspicion given his behavior at a later job. All employees had access to the plaintext passwords of all customers. So they decided to email every customer something that looked identical to a phishing scam, instructing them to click the link and change their password if they ever wanted to access their account again. Then, they made a random alphanumeric password generator, and put a filter so that the user couldn't create a password using common english words. Then, they cut everybody off from their accounts - resellers, dedicated servers, everybody.
Hostgator was considered one of the best of the independent budget webhosts up to this point. After the crisis died down, I suspect they lost a significant fraction of the business they'd acquired in six years of operation over the course of a week. A publicly traded company which is heavily leveraged would have completely folded if a third of their customers dried up overnight... which should scare you. Hostgator was honest and publicly, rightly paranoid about its problems, and if they could have handled it a lot better(pushing passwords downstream automatically, for example), you have to wonder how often large businesses are simply ignoring this kind of thing as operational and career suicide.
http://forums.hostgator.com/forced-password-update-t33170.html?s=28691c684f9a81c71418d734953afc59&t=33170
Personally, it pushed me to try out a password/keyring app called KeePass, which I've stuck to since on computers I own.
There are all sorts of schemes you can use for energy storage, but the simplest in most of the US, for another several years of massive growth, is to just shift the existing hydroelectric turbines down a bit in their ratio of baseload generation to on-demand peak-filling generation.
The drilling of the forbidden regions of the OCS in general is bad because they don't have enough oil to compensate for the risks & publicity, and the drilling off these other coasts *now* is bad because we're still near peak oil consumption, wasting oil at a breathtaking rate & struggling to develop renewables. A better geological survey is probably a wise move, but it should not be a prelude to drilling - yet.
A renewable infrastructure for the country is a difficult thing to develop after the tens of trillion we've sunk into fossil fuels - and a palliative can be a dangerous thing. The low oil prices of the 80's and 90's destroyed most of the conservation efforts of the 70's (not to mention the independant US oil industry), and all indications are that there is no rainbow on the other side of the current storm.
Venezuela, Russia, and Saudi Arabia will be polluted, because Peak Oil is an inevitable global phenomenon with global effects - responsibility be damned. We can choose to put all our efforts into shifting away from oil, or we can choose to make the precipice of oil depletion steeper but farther away by burning everything we have, emptying the SPR, and subsidizing fuel & road construction for a few more years.
Alternately, we can undertake to create the biggest environmental catastrophe possible, and attempt to make coal to liquids, tar sands, and tar shales the standard fuel of the future.
That's an urban myth. Laptops can't run faster than a treadmill - they take off.
A faster option (if you're satisfied with the resolution) would be to do this with a dozen Polaroids at a time, and chop them up using scripts.
There are a lot of photographic details you need to pay attention to here, and external flash isn't necessarily one of them (certainly not the only one).
There are ways to measure population density... and then there are ways to measure population density. Both Canada and Australia have vast plots of mostly empty territory, and most of the population huddled into relatively concentrated cities.
Something along the lines of "Mean number of people within 1km of each household" seems like it deserves a complementary place alongside raw population density.
Australia has less than 1/100th the population density of Japan - but the average Australian doesn't live in a wasteland, he lives in a place that the government designates as "urban" - along with 93% of his countrymen. In Japan, only 66% of the population is designated as living in an urban area.
Speaking very, very generally, the broader spectrum and the higher dose the poison (whatever the poison - animal, vegetable, or mineral), the more difficult it is for a population to evolve resistance against it. Bleach kills almost everything - it's a broad-spectrum disinfectant precisely because organisms have found such difficulty in evolving defenses against a bleachy environment. A very narrow-spectrum poison, perhaps a bioengineered virus which targets a single strand of DNA present in 20% of the population for its high lethality, quickly finds itself going up against organisms which are resistant to its spread. In a generation or two, most of those organisms are dead or have developed antibodies against it, or, in many creatures, have inherited antibodies against it from their mothers. The population routes around the problem, because avoiding that strand of DNA is necessary for survival. Against a wider spectrum poison like high temperatures, a hugely unlikely, very complicated system of heat disposal might be required for any of the population to survive. UV tolerance is relatively easy in human beings (it's been estimated that a thousand years in a different environment is enough to change a population's skin color entirely, from opposing evolutionary pressures involving essential nutrients dark skin can't make, and essential nutrients sunburnt, dead skin can't make), but only because we as large multicellular animals have evolved multiple redundant structures to deal with it - fur/hair, thick layers of dead skin on back and shoulders, variable melanin production adjustable by multiple genes, external means like clothes, houses, hats, and forest canopies, and even short-term adaptations like temporary melanin production during tanning.
Re: The DelMarVa coast - It's warm enough, breezy enough, and wet enough to approximate a beach in summer. With cheap oil, it's a cheap automotive vacation. It attracts everyone east of Appalachia, south of Pennsylvania, and north of Richmond. Somehow it never became an icon - but it is the most popular vacation destination for several million people.
The only inhabitants that aren't supported by the corporate technicalities or the vacation industry are farmers.
The only real increase in household income the bottom 80% of earning households has seen in the last fourty years is from the rise in two-career households.
So take all that you mentioned, and add in a spouse who must do the same thing.
Chalk up spiralling gas, healthcare, and food prices, a popped housing bubble, a weakening dollar, and it becomes rather difficult for all but the rich to survive, economically.
Then you begin to see the situation we're in, and part of the reason the whole political spectrum is moving left - including the preexisting progressives.
Central & west Africa
Russian and northeastern Europe
Bangkok
Hong Kong
Shanghai
The entire east coast of South America
Florida
Seoul
Cape Town
Even so, it's not about using locations where earthquakes don't happen at all, it's about avoiding tunnelling through faultlines. A little vibration isn't going to destroy things.
Average high in LA in July: 84
Average low in LA in December: 50
Annual average precipitation in LA: 14 inches
Average high in Vegas in July: 104.1
Average low in Vegas in December: 36.6
Annual average precipitation in Vegas: 4.5 inches
The reason Vegas gets criticized more than other desert cities is that it sells itself as a place without a culture, an artificial paradise without the need for traditional morals, where you don't have to worry about anything... and it bathes in that sentiment. How long could a single fake venetian canal support the people of the city? The place has quadrupled in size in the last generation - a boomtown where the sole resource is the trivial lack of a few moralizing inhibitions.
All of the desert cities are threatened as the water and the fossil fuels run out, but Vegas is at the pinnacle of unsustainability - its population would flee if given a few libertarian governors in other states, or a single dam failure, or a continuation of the last decade's draught, or a significant decrease in the Colorado River's flow due to water usage upstream, or a major recession, or a few years of $5-$10/gallon gasoline, or a dozen other things.
That's because since WW2, we've spent a hundred billion dollars a year constructing, expanding, and maintaining the roads, and ten million dollars a year tearing up rails so that people wouldn't trip over them.