Please create an account to participate in the Slashdot moderation system


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 internet speed test! ×

Comment Re:Stupid (Score 1) 254

Why change the red light grace period? Red light is red light.

If you want to reduce accidents, increase the yellow period. People who push the limits of an extended yellow don't deserve grace. All this is going to do is now make people more comfortable running a little bit of red.

From the summary: "following recommendations part of a recent study of its red-light cameras. "

or, short version here:

Comment Re:in other countries (Score 1) 254

So basically all the money the government has collected as fines and penalties is distributed evenly to all taxpayers. That money was collected as compensation for crimes against society, and this way it gets distributed back to society.

That's exactly how it works in other countries (e.g.: Switzerland).

Notice what what Kokuyo says about Switzerland in a post above.

Comment Not everybody, just you. [Re:odd thing...] (Score 1) 319

So everybody on this forum who was actually educated about maps being distorted and globes being very common in school is wrong?

No. Not everybody. Just you. Youstate with utter confidence that you know the contents of the classroom and the curriculum of the teaching in every single school in America ... and you can even tell me confidently how things were taught in "middle school" even before you were born. The idea that different schools might have different curricula is apparently beyond your conceptual horizon.

The fact that flat maps are distorted was and is common instruction, EVERYBODY does it, using a globe as the primary instruction tool. It's a way of crossing between history/geography/math, which teachers love.

"Everybody." Really. How in the world do you know that? Everybody where you went to school, perhaps. But unless you have visited every school in America, your confidence is misplaced.

I think that much of your belief about what is taught is probably just a matter of decade. In 1973 Arno Peters had a press conference, and instigated a big flap about map projections, leading to a lot of visibility, even making it to debate in the United Nations-- the "Peters projection controversy."–Peters_projection
Before 1973, the choice of map projection was a technical detail that really hardly anybody knew or cared about, except for cartographers and perhaps mathematicians. After that it became high profile, and it seems reasonable that it might even have made it the middle school curriculum. At least, wherever you live it apparently did.

Comment Lambert and Homolosine [Re:Projections matter] (Score 1) 319

That projection would appear to vastly undersize both Canada and Russia.

What, Lambert cylindrical equal-area? No, it sizes Canada and Russia exactly correctly: that's what "equal area" does.

However, the way it achieves equal area is by squashing the map vertically by exactly the same amount that the sphere distortion expands latitudes horizontally. So if you're thinking of the vertical extent of the country, that's undersized. And, if you're used to other projections, it might look funny.

I'm a fan of the Goode homolosine projection, have been ever since National Geographic used it in the insert of one of their special edition magazines in the 1980's.

Yes, if you get rid of the constraint that you have to map to a rectangular shape, it opens up the choices quite a bit. Those "orange peel" projections do give you a nice visual feel that the map gets wrapped onto a sphere.

Comment the best map of a sphere is a sphere [Re:Projectio (Score 1) 319

Well, the aspect ratio for that one varies according to the parameters you choose, you can squash and stretch it. The Lambert cylindrical equal-area is just one parameter choice.

Yes; I like the un-squashed Lambert cylindrical precisely because the distortion is intuitive: the equator is undistorted, and everything off the equator has exactly the distortion due to perspective (as viewed from theoretically infinite distance at the equatorial plane). Other vertical perspective magnifications don't have any obvious reason for the choice of magnification, other than "make the map undistorted at latitude X."

I used to write code for these projections as part of my job. Decent choice though.

Mercator's most useful property is you can pick an origin and destination, draw a line connecting, and that gives you an initial bearing for travelling between. Keep that bearing, and you will get there albeit not by the shortest distance. Very handy for sailing ships.

Indeed, each of the projections used has one or another advantage. Mercator's great strength is that it locally preserved directions: a compass bearing of X maps to an angle on the map of X, which, as you point out, means you can plot constant-heading trajectories, which is reasonably efficient if your path is short compared to the Earth's radius. As a consequence, for any infinitesimal area, the map is un distorted. It's globally distorted... but not locally distorted.

I quite like the Winkel Tripel but the inverse is nasty to calculate.

Ah, the compromise solution. In real life, the best solution often is a compromise between solutions that are each bad in different ways.

But since we're talking schools, they'd also be well served by a nice spinning globe.

Indeed: the best map of a sphere is a sphere.

Comment odd thing I've noticed (Score 4, Insightful) 319

You were likely playing grabass while they tried to teach it. If you had paid attention you would know _all_ maps are distorted. The PC dweebs just prefer one distorted in a different way. I don't believe your class didn't have globes.

This is a very odd thing I've noticed, and I've see it from both liberals and conservatives: they are unable to conceptualize the idea that other people's experiences may not have been just exactly the same as their own.

Nice of you to tell me what my grade school was like. If I were a woman, I suppose I'd call your lecturing me about what my grade school classroom was like an example of "mansplaining," but since I'm not, I guess it's just arrogance on your part.

Comment Some are more wrong than others (Score 1) 319

No flat map of the world is more or less accurate than any other.

No flat map of the world is perfectly accurate. But some are more accurate than others.

All of them are wrong.

Just because all are wrong doesn't mean that some aren't more wrong than others. There's a great Isaac Asimov essay on that subject:

And the north hemisphere is distorted in exactly the same way that the south hemisphere is.

Even there, you're mostly wrong. Grab your dictionary and take a look at the Mercator maps (here, for example, or here): they very rarely have the equator in the middle. The reason they don't is that if the map goes all the way north to show Alaska and Scandanavia, then if they want equally far south, Antarctica becomes absolutely huge on the map.

Comment Mercator straight lines are not great circles! (Score 2) 319

On the Mercator projection. straight lines map to great circles,

No! No, no, no, no!

In the Mercator projection, straight lines do not map to great circles-- the only straight lines that are great circles are meridians and the equator. Plot a great circle route from, say, New York to Berlin. It goes way north of the straight line on a Mercator projection.

(In fact, there is no possible mapping in which all great circles map to straight lines, nor all straight lines to great circles. That's non-euclidean geometry for you.)

This, in a nutshell, is exactly why we should stop having Mercator maps be the standard.

useful for navigation.


Comment Re:Never had a globe? (Score 1, Interesting) 319

Huh. We certainly didn't learn about map distortions in middle school, nor in high school either, for that matter-- maybe that must be something that was added to the middle-school (we called it "grade-school" when I was a kid, shows how old I am) curriculum since I grew up.

Not all classrooms have globes: our grade school didn't.

I think it makes sense to use a better standard map in classrooms-- the Mercator projection is just plain misleading. I don't see why should it be "PC crap" to use a map that's not vastly distorted in area. I'd call that just common sense.

Comment Projections matter (Score 5, Informative) 319

I agree; Mercator's projection is not deliberately designed to minimize Africa. That is incidental. But, nevertheless, it is a side effect. As a kid, I was always puzzled as to why Australia is a continent, but Greenland not, when on the map Greenland is clearly larger.

I'm a fan of the Lambert cylindrical equal-area projection, which seems to be geometrically very clear and straightforward, although it has a odd (pi to 1) aspect ratio.

And, of course, the obligatory xkcd.

Comment Welcome to the real world, why don't you just die (Score 4, Insightful) 283

...Sometimes people just have to live with the consequences of their own decisions, even if that means dying. That includes choosing not to buy insurance and subsequently being unable to afford a necessary medical procedure.

That is a logical and self-consistant attitude: the solution to people not buying insurance is that they should just die.
If Republicans would just honestly state it that way, I'd be ok with it.
--they would have to stop saying that they're "pro life," of course.

Comment Re:Tough shit -- welcome to the real world (Score 1) 283

Total whoosh. You don't need to save enough to pay for the medical bill, you only need to save enough to be able to pay for the insurance. That's your 'share'. If you foist this expense onto the rest of society, you're screwing over everyone else. Nobody expects any single person to be able to come up with millions of dollars for a medical procedure. That's what insurance is for. The problem is the people who don't think they should have to carry insurance but still expect the care when the time comes.

And the Republican solution is to let those people who don't think they should "have" to carry insurance not get insurance.

That's freedom. But we as a society have made the decision that we aren't allowed to tell them "ok, you didn't buy insurance, so just die." So then we get to pay for them when they need care.

Comment Re:Tough shit -- welcome to the real world (Score 1) 283

this is why i cant stand liberal democrats, always thinking other people should pay for their decisions

Actually it was Ronald Reagan, not the "liberal democrats," who signed the federal law that hospital emergency rooms couldn't turn people away just because they can't pay.

This is, basically, the unfunded federal mandate that Obamacare is solving: when people with no insurance have no other way to get medical care than to go to an emergency room, and everybody else has to pay for that very expensive way of getting medical care, it makes sense to require people to have insurance.

Slashdot Top Deals

The means-and-ends moralists, or non-doers, always end up on their ends without any means. -- Saul Alinsky