Navigation bug when going reverse

[NigelM]

It's not necessarily a "bug", but it's doubtful that it's what you actually want. e.g. it can be a little disorienting if you need to back up out of a parallel parking spot (or worse, shimmy back and forth a few times), and the GPS keeps rerouting you each time you switch: am I supposed to go forwards or do a U-turn right now? Halfway through turning around you run out of space, so you need to make it a K turn instead - you back up, and the GPS reroutes you again, etc..

It's not the biggest deal in the world, and likely not even considered a bug, but the preferred behavior would be for the GPS to route based on the direction my car is facing.

I'm confused.

If you're parallel parked why would you back out of the spot? AS you say even if you do back up you'd then have to pull forward anyway. The chances of being able to do a straight U-turn on a street with parallel parking are slim in any case. If you're in off-street parking then it doesn't matter which way the car is pointing, you still have to get to the road to get to the start of the navigable route. If you're reversing down your own driveway then you're perpendicular to the NAV route and it doesn't re-route till you get to the road anyway.

Also, IIRC when the car is in reverse doesn't the rest of the screen around the reversing camera grey out anyway?

 

[PhilBa]

In his defense, Nigel, you do sometimes have to back up a bit in order to be able to clear the car in front. I assume what he was seeing is the left hand instrument panel with the head-up routing display.

 

[kjl]

I'm confused.

If you're parallel parked why would you back out of the spot? AS you say even if you do back up you'd then have to pull forward anyway. The chances of being able to do a straight U-turn on a street with parallel parking are slim in any case. If you're in off-street parking then it doesn't matter which way the car is pointing, you still have to get to the road to get to the start of the navigable route. If you're reversing down your own driveway then you're perpendicular to the NAV route and it doesn't re-route till you get to the road anyway.

Also, IIRC when the car is in reverse doesn't the rest of the screen around the reversing camera grey out anyway?

I am talking about the dash display, for which "up" always faces, well, the direction the arrow is facing, which is towards the nose of the car.

Imagine a world, if you will, in which:

1) I go to some restaurant with no reasonable parking anywhere in downtown Oakland or some neighborhood I've never been to in San Francisco, where the streets aren't aligned with the grid, and in any case, because I am dumb, I don't even know which direction the nearest freeway is, which way the nearest onramp is, or even which way I'm facing (because face it, I just blindly followed the nav till I got in the area, and then circled randomly for 25 %#^$ minutes trying to find parking in this god forsaken city while screaming at my girlfriend, who's probably crying by now.)

2) Later, I come out of the restaurant, get in car, have no idea where I am or what direction I'm facing, and say "Navigate to MY ADDRESS". Nav says to take a u-turn and turn right.

3) I back up a foot so I can clear the front corner of the car in front of me when I pull out. The Nav flips around but now says to go straight and turn left at the end of the block.

5) I should know the correct direction to go (I should know that the original directions to u-turn then right is correct, and that the other was "reversed"), but I'm distracted because my girlfriend just dumped me because I yelled at her before dinner, so I think "forward" is the right direction.

6) I pull out and drive 3 feet forwards and the Nav flips around again and tells me to make a U-turn.

7) There's no good place to U-turn right here (I should have turned around when I pulled out of the parking spot, but too late now!), so I'll just go another half block and turn around in a driveway ahead.

8) I pull into the driveway and at that second the GPS reroutes because it found a closer route to a different onramp because I went too far in the wrong direction.

9) I back up again and the Nav flips around and now I have no idea what's going on anymore.

10) My brain explodes.


No, I'm kind of kidding; it's not really that big of a deal. However, I would say that I don't really care that much about the center console. What's silly is that the dash panel flips around. The dash panel is always oriented correctly and intuitively except when in reverse. Looking at the 3D Nav graphic on the dash display always shows what you see in real life by looking 5 inches further upwards, out your windshield, except when going in reverse, when looking at the dash display gives you an image of what you'd see looking out the back window. That seems counterintuitive.

 

[NigelM]

^^^ Don't yell at your girlfriend; you're better off giving her the keys and letting her drive you.....:wink:

 

[hans]

Does it have a magnetometer or use successive gps reading to figure out direction? I had exactly the scenario I described last night - it had me going the opposite direction before starting out, flipped as I pulled out and then flipped again when I had completed the turn. This took maybe all of 5 seconds. It surprised me that it did that so fast. If it has a mag, it could be biasing towards the GPS readings over the mag. The gps in the tesla seems really good, by the way, the updates are very quick. Phones use a lower update rate to save battery so you get a coarser set of points.

I believe it has a magnetometer because the streaming log data reports both "heading" and "est_heading" (estimated heading) and the two values don't often match.

 

[Darren]

Okay, this may not be a bug, but it's certainly not expected. I was tripped up when the left part of the dash with the perspective view, which I thought pointed in the direction of the vehicle, reversed.

 

[PhilBa]

One thing is becoming clear, the car may have a mag but nav doesn't use it.

 

[hans]

One thing is becoming clear, the car may have a mag but nav doesn't use it.

Correct, at least for the center console map. That's why we only have north up orientation. Sounds like you're saying turn by turn nav is also getting its estimated heading from GPS.

 

[PhilBa]

I don't think the car has a mag (or doesn't use it at all). North Up display isn't because there is no mag - you don't need a mag to determine travel direction.

I did a little experiment where I put the car in neutral and rolled backwards. Within about 3 feet the map showed the car heading backwards -the arrow head pointed in the direction I was moving. It took less than a second for that arrow to flip around. In addition, the arrow was very stable - no detectable jitter. Google maps/nav on my phone uses successive GPS readings to determine direction and it jitters quite a bit, especially when stopped but also at slow speeds.

So, I conclude several things from this little test:

• Telsa maps and nav don't use a mag at all. The car probably doesn't have one.
• Maps and navigation use successive GPS readings to determine direction.
• I believe the Tesla GPS has a high update frequency - probably 10 hz or better.
• The GPS (or map/nav) subsystem does a really great job of filtering noise to make for an extremely sable heading estimate.
• Because of the high update rate, it very quickly determines heading.

In summary, I think Tesla has done an extremely good job with their GPS system. High quality hardware with some excellent filtering. Anyone know which GPS they are using?

On the subject of nav bug that started this thread - I think it makes sense for nav to wait until the car has traveled at least a short distance (10-20 feet) before deciding to reroute as the rerouting that it did for me (as reported above) was useless and confusing. Not a bug per se but I wouldn't call it a feature, either...

 

[Denarius]

Frankly, I'd rather Tesla spend their time adding new features and fixing real bugs instead of worrying about something as trivial as this. I want the GPS to update instantly if I make a wrong turn. "Fixing" this "bug" would make the rest of the GPS experience worse. If you are going to go into reverse out on the road (which is illegal anyway) then you can deal with the GPS being wrong until you go forward again.

 

[twinklejet]

Frankly, I'd rather Tesla spend their time adding new features and fixing real bugs instead of worrying about something as trivial as this.

I agree! I mean, afterall, at least your car isn't doing what this BMW does:

 

[hans]

I don't think the car has a mag (or doesn't use it at all).
...
[*]Telsa maps and nav don't use a mag at all. The car probably doesn't have one.

The car has wifi even though it doesn't use it so I wouldn't be so sure that something isn't there, just because the current console apps don't show it.

What do you think the difference is between "heading" and "estimated heading" as reported by the car and why do you think they are different numbers?

Estimated heading sounds like something calculated from successive gps samples but could be 3G or wifi based for better speed.

Heading sounds like a single reading (like from a compass). It could be a triangulated heading from the 3G or an accelerometer or a gyroscope or something else but it IS something else and it is another way to get a heading other than the mechanism used by the map.

You can find out a lot about the system that Tesla's display is based on here.

Automotive Infotainment & 3-D Navigation Systems | NVIDIA Tegra | NVIDIA

Unfortunately it is not enough to understand exactly how the nav and map systems are built but it does make me feel confident that 4G LTE is coming, along with some cool image processing functions like pedestrian detection, night vision, parking guidance, and lane departure.

 

[brianman]

I agree! I mean, afterall, at least your car isn't doing what this BMW does:

The music in this video was the wrong choice.

It really should have been:

 

[PhilBa]

The car has wifi even though it doesn't use it so I wouldn't be so sure that something isn't there, just because the current console apps don't show it.

What do you think the difference is between "heading" and "estimated heading" as reported by the car and why do you think they are different numbers?

Estimated heading sounds like something calculated from successive gps samples but could be 3G or wifi based for better speed.

Heading sounds like a single reading (like from a compass). It could be a triangulated heading from the 3G or an accelerometer or a gyroscope or something else but it IS something else and it is another way to get a heading other than the mechanism used by the map.

You can find out a lot about the system that Tesla's display is based on here.

Automotive Infotainment & 3-D Navigation Systems | NVIDIA Tegra | NVIDIA

Unfortunately it is not enough to understand exactly how the nav and map systems are built but it does make me feel confident that 4G LTE is coming, along with some cool image processing functions like pedestrian detection, night vision, parking guidance, and lane departure.

To be honest, the car might as well not have one if they don't use it for maps and nav. Not sure why you are so in a snit over this. Not sure it really matters.

By the way, using a mag is more complex than you would think because you have to compensate for 3D orientation. If they actually have one, it may be too much CPU work to actually use - successive approximation of heading is probably just as good at a fairly low cpu complexity.

And good luck with all those features retrofitted into an already shipped MS.

 

[hans]

To be honest, the car might as well not have one if they don't use it for maps and nav. Not sure why you are so in a snit over this. Not sure it really matters.

I'm not at all in a snit, I guess I'm just poor at communicating I am only interested because I am writing my own apps for the car, some of which involve the GPS and heading data. This is just not the right thread to discuss the internals of the nav system. My mistake, apologies for derailing the discussion.

Console map shows heading going southeast, dashboard nav simultaneously shows heading going northwest. Easy to duplicate by putting the car in reverse and backing up until dashboard nav flips the wrong way.