Altitude display wrong

[BillArnett]

The altitude display is sometimes badly off. I drove up to Lick Observatory yesterday which is at about 4200 ft and when I stopped the display said 2200. It got better after approx 30 minutes in Park. When I got back to my home at 740 ft the display said 336 and stayed that way for hours in my garage. Later I drove it out down the street a little way and the display corrected itself.

Does it need to update more often? Of course, its data is from the GPS and its horizontal location is updated much more rapidly.

This display is completely useless unless it’s correct.

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[iowa_don]

The altitude display is sometimes badly off. I drove up to Lick Observatory yesterday which is at about 4200 ft and when I stopped the display said 2200. It got better after approx 30 minutes in Park. When I got back to my home at 740 ft the display said 336 and stayed that way for hours in my garage. Later I drove it out down the street a little way and the display corrected itself.

Does it need to update more often? Of course, its data is from the GPS and its horizontal location is updated much more rapidly.

This display is completely useless unless it’s correct.

Mine is eerily accurate. Driving from Phoenix to Flagstaff, it is within 10 ft of the elevation signs posted and updates continuously. Sounds like a SC appointment needed.

 

[BigSkies]

Mine has been consistently close-ish. I'll sometimes compare it to the elevation markers when going over a high pass. It can be off by a couple-hundred feet.

My first time over Vail pass set an altitude record, and my second time over was higher by something like 200ft.

While I don't know what they're using to measure altitude, it kinda feels like a barometric altimeter, as those are influenced by weather. Which would be a weird way to measure it because the vehicle has GPS available.

Here's my reading on both the highest and lowest points you can drive to in North America.

 

[Andy Wallace]

Mine seems fairly accurate… except for a little quirk that shows the minimum altitude my truck has been to: -75 feet. Now I plan on going to Death Valley, but I’ve not been there with Dive Buddy yet.

 

[bigsky]

Used many times, elevation data on my R1S is spot-on. Verified and confirmed spot-on accurate. Quite precise as well.

 

[rpo]

Mine seems to be dead on accurate all the time. My Garmin watch, on the other hand, is sometimes off by hundreds of feet.

 

[schlosrat]

2024 Gen 1 R1T here, and mine is routinely inaccurate. When I lived in Florida at an elevation of about 15', it would often indicate I was at -330 ft or other such nonsense. Given that it's got accurate horizontal position info, it would be fabulous if it just used that info to pull correlated altitude info from a map database, but I don't think it does - or at least it didn't the last time I bothered to check (~9 months ago). I quickly learned to ignore the altitude since it's stupidly wrong.

Has it improved in an update sometime since I last bothered to look? I don't recall an update note about improved altitude accuracy.

 

[Zoidz]

It's likely that you had minimal/sporadic reception, and as time went by, additional signals were received to improve the accuracy.

I read up a bit on GPS elevation calculation a few years ago because I noticed errors. It turns out that GPS Elevation is more challenging to get an accurate calculation for many reasons. For most modern GPS receivers, it seems that 4 satellites minimum are required to provide a location - not 3 as is commonly thought. Modern GPS does not work on triangluation, it uses trilateration. The forth satellite is used to validate the time reference, so in a real sense GPS works in 4 dimensions. The number of satellites visible increases the accuracy, and their location (overhead vs lower on the horizon) actually affects the calculation accuracy. Atmospheric distortion of the signal can also affect the accuracy, as well as the remote possibility of reflections off of a hard mountain face.

It could locate in 2 dimensions and then pull the elevation from a topo map, but those are typically less granular, and would likely cost Rivian more money due to the API calls to get the data. It's not free for commercial use.

 

[Dasoss]

The altitude display is sometimes badly off. I drove up to Lick Observatory yesterday which is at about 4200 ft and when I stopped the display said 2200. It got better after approx 30 minutes in Park. When I got back to my home at 740 ft the display said 336 and stayed that way for hours in my garage. Later I drove it out down the street a little way and the display corrected itself.

Does it need to update more often? Of course, its data is from the GPS and its horizontal location is updated much more rapidly.

This display is completely useless unless it’s correct.

We get spoiled by the remarkable horizontal accuracy of GNS. The vertical accuracy is always worse. The position accuracy depends on the number and location of satellites in view of the receiver, among other things. This called geometric degradation of precision (GDOP). It affects altitude accuracy more because all of the satellites are far above the receiver.
Barometric altitude sensors are greatly affected by local atmospheric conditions--weather. In addition some navigation systems merge the GNS data with other data like inertial data, and dead reckoning to provide continuous information in dead spots. Satellite receivers require between 1 and 10 seconds of averaging time for accuracy. They require a few seconds from signal loss. The receiver needs a clear view of the sky. All this handled by a statical procedure called a Kalman filter, that sort of averages all inputs taking into account their estimated accuracy, and knowledge of physics. In summary, altitude is hard to measure in a vehicle. The altitude listed on the signs and maps can vary depending on when and how they were surveyed. The earth is not quite spherical. There have been several geometric models of the shape of the tree earth. It's likely that your Rivian is reporting altitude with expected accuracy.

 

[JacobAZ]

My elevation is accurate (within about 30') when driving. It's using GPS, same as detecting truck location. So, when parked in a garage it can't see satellites and isn't reading satellites. But it also does not display the last known altitude. Instead displays some other number. But as soon as I drive it updates accurately. I believe this is what the OP is experiencing.

 

[CO-Ed]

I've been experiencing very accurate elevation readings when I have the Drive screen on the center display - I routinely drive from western Colorado to Denver and summit the two tall passes and the display matches very closely to the topo maps I have on my phone.

However, if I reset the Elevation display on the Drive screen, like for a trip, and then select another screen on the center display, the max elevation doesn't update. So, when I drive from Grand Junction to Denver, having to travel over the 10,600 ft Vail Pass and through the EJ Tunnels at 11,300 ft, the truck displays the max elevation as the highest elevation the truck was at WHEN and ONLY WHEN the Drive screen is on the center display, not the actual max for that trip - which in this case would have been 11,300 ft.

I've tested this theory a few times and it seems very consistent, and a software bug. For instance, two days ago driving from Grand Junction to Denver I did the elevation reset before the trip and didn't pull up the Drive screen again until I was about 5ish miles east of the EJ Tunnels. The display showed the current elevation as 9100 ft and it showed the Max Elevation as 9100 ft, not 11,300 ft which was the max elevation I actually drove.

I'd be interested to hear if anyone else is experiencing this.

 

[Mathme]

Mine is usually spot on accurate but there are times when it is not. I've from Palo Alto to South Lake Tahoe probably about 20% of the time going over Echo Summit (7420 feet) my truck says something lower that's totally inaccurate (like 6600 feet), only to turn around and drive back the same way 2 days later and it's accurate again. I'm not sure why it does this as the trip there requires about 2 hours of driving at basically sea level before climbing so the sensors have had plenty of time to calibrate.

I don't stress too much about it and let it read what it will.

 

[JacobAZ]

However, if I reset the Elevation display on the Drive screen, like for a trip, and then select another screen on the center display, the max elevation doesn't update. So, when I drive from Grand Junction to Denver, having to travel over the 10,600 ft Vail Pass and through the EJ Tunnels at 11,300 ft, the truck displays the max elevation as the highest elevation the truck was at WHEN and ONLY WHEN the Drive screen is on the center display, not the actual max for that trip - which in this case would have been 11,300 ft.

I've tested this theory a few times and it seems very consistent, and a software bug. For instance, two days ago driving from Grand Junction to Denver I did the elevation reset before the trip and didn't pull up the Drive screen again until I was about 5ish miles east of the EJ Tunnels. The display showed the current elevation as 9100 ft and it showed the Max Elevation as 9100 ft, not 11,300 ft which was the max elevation I actually drove.

I'd be interested to hear if anyone else is experiencing this.

I don't actually know if my Gen 2 does this with the max/min elevation. I will have to check it out. I rarely pay attention to elevation. I mostly use the screen for battery and motor temp as well as efficiency. So, I am on and off the screen. However, as a former software developer and designer I could see what you experience as intentional, and not a bug. Step 1, The GPS is getting a stream of data to calculate a stream of real time elevation. Step 2, computer is sending this stream of elevation to the display, but only when screen is displaying. Step 3 the stream of elevation data must constantly be comparing current value to high and low saved value. If it exceeds then new value is saved High or low. As a software engineer, for the sake of efficiently I could see the design to only format the data for display when the screen is up, and only do the high low compare at that time.

 

[CO-Ed]

As a software engineer, for the sake of efficiently I could see the design to only format the data for display when the screen is up, and only do the high low compare at that time.

I hear you with this but it would be the only values on this screen that don't update while on other screens. Plus, what good would max and min be if they didn't track the trip regardless of the screen you're on.

I noticed today that the elevation, min elevation, and max elevation all don't calculate unless you're on the drive screen and not in park. I did the reset and left the drive screen. Drove from home at around 7500 ft to Grand Junction at 4500 ft. Parked, and let the truck sleep. When I came back to the truck it woke up and I selected the Drive screen. Min, Max and Current elevation were 7470-7476 ft but I was at an elevation of around 4500 ft. Put it in gear and the current elevation immediately went to 4553ft, max was 7476, and min was 4553. Either there's a software bug or my truck has an issue.

These two pictures were taken 23 seconds apart.

So I'm wondering if what some experience as elevation error is because they're on the Drive screen when they hit the peak of their travels (or the max elevation they expect) and the truck isn't calculating when they're not on the Drive screen.

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