Some does, some doesn't. I've worked with the HFE-7500 stuff, which DOES evaporate really fast (much, much faster than water) -- as a result, you can also smell it a little bit, which can be annoying after a while. It also has a pretty low viscosity, which means that it tends to leak through any seals.
On the other hand, the FC-73 stuff (which I've also worked with, though not as much) doesn't evaporate NEARLY so fast as water, and is more viscous, so it doesn't leak very quickly. It also doesn't attack silicone seals nearly so much as the HFE. For home hobby stuff, I'd recommend FC-73 over HFE.
Every time I see "RMS" I think "Root Mean Square -- that can't be right!" Then I remember who we're talking about, parse the words a little differently, and think, "Actually, it's entirely apropos."
My project isn't *extremely* concerned with precision, but for a monochromatic light source and a nice background, one can easily obtain depths to ~1/50 mm from shadow-shifts. This is about one part in 500 of the object height. For two monochromatic sources, the precision increases to about 1/70 mm. More sources increase the precision a bit, but due to specularity and diffraction effects, white light decreases the precision a little bit.
There's also hydrofluorinert (generally available from 3M) which has some slightly different properties (higher vapor pressure, for one, so it evaporates easier). However, before anyone goes out to play with HFE, they should know that it likes to dissolve [into] silicone seals a bit more aggressively than the other fluorinerts. This is a good thing sometimes, but in the case of a computer cooling system, it might cause big problems.
Please. When I write papers, I reference works all the way back to Newton, Galileo, and even before (a nice habit inculcated in me by my former advisors and current boss), and I *know* that much of what I do is not new (or, if it is new, it usually only new in the context of the field in which it's placed).
What I was apparently being "haughty" about was the breathless way in which advancements are lauded on the front page of slashdot as though they're revolutionary. To not acknowledge the significant corpus of works which have gone _before_ is perhaps not arrogant, but at least misleading and careless.
Perhaps the previous slashdot story wasn't "old" -- if you count things post-2004 as "new". However, even the paper in the.pdf notes that people have been concertedly using these techniques since 1998, and I happen to know that a lot of the work was pioneered as early as the mid-1940's with depth-maps and stereograms. The new work IS nice, but it's not totally new.
You're right -- my way requires two flashes (it really doesn't, but we found it slightly more effective that way). The old slashdot article which I mention (but don't reference) also talked about only needing one camera. I think that it said that Chilton's Repair Manuals was using both techniques to produce their series of DVDs. Of course, I could be really wrong!
Slashdot (can't be bothered to find it) had a story several years ago about the (then old!) technique of capturing complicated 3D objects, such as car engines, by using two flash images, each with the flash located in slightly different locations. Threshholding the difference between the images gives very nice edge detection, along with very accurate depth information.
A project I'm working on uses the technique to capture information about arrowheads/spearheads.
Dials which only have settings of zero and > 0 don't scare me. It's those which have only 0 and 11 that we have to be wary of. In this case, the setting of non-zero is labeled "none more black" and no one has ever survived that one.
Slashdot Mirror
Huh. My first inclination was going to be to make a "None. None more black." joke, but with Oprah, well, I just can't tell.
... in my over-20 years of education, is that some things just aren't worth reading.
But, but... It's so scrumptiou--- ooh! shiny!
According to the MSDS for FC-73, it is NOT a threat in any way to the ozone layer. However, it *is* a long-term greenhouse gas.
2) The stuff evaporates really fast
Some does, some doesn't. I've worked with the HFE-7500 stuff, which DOES evaporate really fast (much, much faster than water) -- as a result, you can also smell it a little bit, which can be annoying after a while. It also has a pretty low viscosity, which means that it tends to leak through any seals.
On the other hand, the FC-73 stuff (which I've also worked with, though not as much) doesn't evaporate NEARLY so fast as water, and is more viscous, so it doesn't leak very quickly. It also doesn't attack silicone seals nearly so much as the HFE. For home hobby stuff, I'd recommend FC-73 over HFE.
Every time I see "RMS" I think "Root Mean Square -- that can't be right!" Then I remember who we're talking about, parse the words a little differently, and think, "Actually, it's entirely apropos."
I, for one, don't like Obama or McCain.. Barr '08!
Barr?!? She couldn't even sing the National Anthem several years ago...
Sigh... damnit.
OK, Frank will be along soon. She's, erm... got a great personality.
Good luck with that.
... someone explain all the rules to me again?
Ask and ye shall receive. http://www.fugly.com/videos/1424/poontos.html
Getting it to *weigh* one kg -- now there's a challenge!
It's a perfectly cromulent English flutzpah!
It just looks bad the way they plotted it, with no error bars on the red sine wave.
Er... and what error bars should they put on the 1/(Earth-Sol)^2 distance curve?
Thurber said, in response to someone who said his stuff was great in French: Yes, my works lose something in the original.
That was my favorite part, too. It started off kind of slowly, but the ending was great. Maybe Stephenson could learn to write in Czech.
My project isn't *extremely* concerned with precision, but for a monochromatic light source and a nice background, one can easily obtain depths to ~1/50 mm from shadow-shifts. This is about one part in 500 of the object height. For two monochromatic sources, the precision increases to about 1/70 mm. More sources increase the precision a bit, but due to specularity and diffraction effects, white light decreases the precision a little bit.
11, maaaan.
There's also hydrofluorinert (generally available from 3M) which has some slightly different properties (higher vapor pressure, for one, so it evaporates easier). However, before anyone goes out to play with HFE, they should know that it likes to dissolve [into] silicone seals a bit more aggressively than the other fluorinerts. This is a good thing sometimes, but in the case of a computer cooling system, it might cause big problems.
Please. When I write papers, I reference works all the way back to Newton, Galileo, and even before (a nice habit inculcated in me by my former advisors and current boss), and I *know* that much of what I do is not new (or, if it is new, it usually only new in the context of the field in which it's placed).
What I was apparently being "haughty" about was the breathless way in which advancements are lauded on the front page of slashdot as though they're revolutionary. To not acknowledge the significant corpus of works which have gone _before_ is perhaps not arrogant, but at least misleading and careless.
http://groups.csail.mit.edu/graphics/pubs/siggraph2004_nprcamera.pdf
Perhaps the previous slashdot story wasn't "old" -- if you count things post-2004 as "new". However, even the paper in the .pdf notes that people have been concertedly using these techniques since 1998, and I happen to know that a lot of the work was pioneered as early as the mid-1940's with depth-maps and stereograms. The new work IS nice, but it's not totally new.
You're right -- my way requires two flashes (it really doesn't, but we found it slightly more effective that way). The old slashdot article which I mention (but don't reference) also talked about only needing one camera. I think that it said that Chilton's Repair Manuals was using both techniques to produce their series of DVDs. Of course, I could be really wrong!
Slashdot (can't be bothered to find it) had a story several years ago about the (then old!) technique of capturing complicated 3D objects, such as car engines, by using two flash images, each with the flash located in slightly different locations. Threshholding the difference between the images gives very nice edge detection, along with very accurate depth information.
A project I'm working on uses the technique to capture information about arrowheads/spearheads.
Dials which only have settings of zero and > 0 don't scare me. It's those which have only 0 and 11 that we have to be wary of. In this case, the setting of non-zero is labeled "none more black" and no one has ever survived that one.
That was Tonya Harding.
What do you call the guy who shovels the coal into the locomotive and generally tends the fire again?
Mister Tibbs?