redpaul

How does the navigation system choose its routes?

Around familiar places, I have noticed how the navi system seems to prefer main roads, where my own experience has learned short cuts and "better" alternative routes. Sort of what I expect. It seems an algorithm sorts through the relative size of the roads and compares the distance and selects a route that balances the two.

I am currently on a long trip and have found the navi invaluable but some odd quirks (unusual features) have appeared. On a long 500-mile route yesterday, the system selected a route at the start of the trip. We scoped out the directions list and it jibbed with the route we plotted on paper. Then after a rest stop (the car has a 17 gal. tank but the operators have 8oz storage capacity ) we resumed the route, but now we noticed that the route had changed to another alternative, using a less major highway. Later while in route the directions list changed again. (When you have gone through all 6CDs, Auto Select can't find anything worth listening too, what else are you going to do but fool with the navi?) We got to our destination just fine, be we are wondering what is going on in the black box in the trunk.

So anyone have an insight as to how the navi chooses routes?

P.S. It is very cool to cross a time line and have the clock automatically change!

Whiskers

IMO I think the NAV is really only useful if you are lost. It will get you from point A to point B, but not always the best way. If you enter a destination you are familiar with, you will think the thing is retarded sometimes by the way it will take you. The funniest is when it tells you to keep on a route, but if you take a better route, the mileage and time will go down. I think it has a lot of algorisms (which I think is your questions) such as road speed limit, type of road such as highway compared to dirt road, etc. Also keep in mind that it doesn't know of newer roads. Improvements are needed, but it’s still worth it for the times you are lost.

Axygos

An odd thing I've noticed with the navi is that sometimes it does stupid things... while approaching the Washington, D.C. beltway on 270, it tells you to go on the local side of the highway, once there it tells you to go to the express side, then back to local, then express.... crazy!

Though all in all I find it quite useful... only wish it had additional options like "Shortest Route" and "Quickest Route" as part of its menu...

Whiskers

I thought it did

biker

It's all software magic.

Whiskers

CGTSX2004

iTrader: (1)

I'd imagine the software algorithms must incorporate a number of factors, including posted speed limit, number of intersections (stop signs and signal lights), relative size of road, and distance. Somehow, from all this information, it selects a route. The good thing is that the navi will constantly recalculate the route if you deviate from the posted route so if you know a shortcut, you can always take it without worrying about the navi.

MoFocker

which of the options usually chooses the route with the less miles? sometimes when i choose quickest route and go a different way then what it tells me, it will recalcalculate and the direction I decided to take turns out to be fewer miles (im talking 5-7 miles shorter each time).

CGTSX2004

iTrader: (1)

I would imagine that shortest route is supposed pick the shortest distance. Quickest route should be the shortest time.

a_TSX_4_Me

When driving down to DC and back up to Baltimore from NoVa, the Navi will tell me all sorts of crazy ways to get to Baltimore, flat out disagreeing with the street signs!! I still love it though, because it works perfectly 99% of the time, and provides me with the sense of direction that I wasn't born with ;-)

End of the day, it's a pretty amazing system, even when it screws up

~ Steven

Axygos

I didn't think my navi had the options of quickest and shortest... I thought it was just "direct" or something like that... I'll check when I get in my car soon.

sipark

const char *ch1 = "noob";
printf("You're a %s!\n", ch1);

biker

Spoken like a true code geek.

Biker, who opted not to major in computer science.

Whiskers

All I remember is some BASIC

10 CLS
20 For x=noob
30 Print x
40 Next
50 Goto 20

Hojo061782

It was a valiant effort, but how about this?

10 CLS
20 X$ = "Noob"
30 PRINT X$
40 GOTO 20

I think that will do what you intended.

Whiskers

Thanks, but I like my if then statements!!!

darth62

Program Wsklar (Input, Output);

Var

X : Integer;

Begin

X: = 1;
While X < 2 do
writeln ("I like Cheetos");
End.

Whiskers

Hojo061782

leet(hojo).

is_leet(User,Answer) :- leet(User), Answer is " is ".
is_leet(User,Answer) :- Answer is " is not ".

who_is_leet(User) :- is_leet(User,Answer), write(User), write(Answer), write("the most leet programmer!"), nl.

?- who_is_leet(hojo).

Tsx536

visual c++

:TryAgain
if(AfxMessageBox("Are you a noob?",MB_YESNO) == IDYES)
{
AfxMessageBox("I'm glad you already know!!")
}
else
{
AfxMessageBox("Yes you are!! Try again!!");
goto TryAgain
}

Ozzman

I have the navigation and love it, but it is does run on a Microsoft operating system, so why is anyone surprised that it doesn't make sense. I'm just waiting for a navigation route that tells me to go to a website and give over all my personal info.

TimJ

Since it is a Microsoft OS running it, I'm surprised it doesn't tell you to download a new update everytime you start the car! I hope you're kidding about it being a MS operating system...

Whiskers

It runs a modified Windows CE OS.

TimJ

That sucks, oh well...at least it works. I love having the Navi, seems to make a long trip go by faster just playing around with it and hey, it's usefull too! It does make some weird decisions on routes sometimes though.

pandimus

sorry to let you guys down but there is a magic 8 ball in everyones dash, and when you ask for a route it shakes it up and gets advice from there...

TimJ

Well that's gotta be more reliable than a Windows OS

Ozzman

Then this must be the new navigation quickstart guide . . .

http://www.mattelgames.com/magic8/flash_index.asp

redpaul

Back from my long trip and reading through all your comments.

Thanks for the programming insights now I know why I didn't into computer science. Thanks for the Magic 8 ball link; I wonder if that isn't the navi system from a Yugo.

The system has its quirks.

We found that the system's first route from Clovis New Mexico to Austin Texas was something on the order of 600+ miles and 14+ hours of driving. Using a map (embarrassing, I know) we found a route that was about 450 miles and 12 hours (by the systems estimate). We were able to program that route in the "Avoiding streets" by successively deselecting multiple roads from the menu screen.

We found the system seemed to recalculate on its own enroute. We'd set up a route, review the street listing, drive for a while and then check the street listing again and find some of the later streets had reverted to previous streets or even new routes.

I have no clue were the estimated times come from. Around town the times have been a bit out of whack but on a daylong drive they can be scary! (If the estimates we saw were accurate, I'd still be driving.) I suspect time is based on the type road X distance calculation. I correct the estimate in my own mind by subtracting about 30% to 50%. It would be great if there were options that let you adjust the estimate in some way.

Annoying is the system's recalculating a route after the engine has been turn off and then on (to refuel) based not on our programming but it's own easiest or quickest programs. The significant other was most patient in reprogramming the thing – what else you going to do on long drive?

Still despite the above quirks the system proved invaluable.

As we neared our destination in a new city we navigated through city streets we’d never seen like natives. Even when we missed a turn we could get back on route.

At night and during a heavy day light fog it was great to know in advance that the road would curve left or right and that a town or crossing was just ahead. We felt a lot safer.

And I believe that if we hadn’t sought a short alternative route we would have driven further but the time wouldn’t have been that much longer. Our return trip took about 8 hours verses the 12 that was estimated.

GSI

I have been most sucessful with the system set to Easy. It is fun to trick the system with the short cuts that I know in town. I always wonder when I am out of town if the NAV is taking me the long way when I am doing city driving because it sure does pick some wacky routes when I am in my city.

The ETA is based on the speed that the law says you can go and that's why you end up doing a 12 hour trip in 8 hours. Now if you drove 55 - 65 mph on your trip then it would take you 12 hours to get there.