[closed] Exporting GPX with barometric elevations?

[kepPNW]

Seems to be a wide disparity between the elevation gain shown for a given track within AlpineQuest, and that shown by the exported GPX track. For instance, yesterday's hike shows 5400' EG, but the GPX after being imported into Garmin Basecamp shows 8600' EG!

How do I export the dampened data? Thanks!

[Psyberia-Support]

Hi,
I think there is two different things here:
- The application does apply a noise correction algorithm when displaying stats on tracks. It results in a smaller gain, closer to reality than when computing raw elevation diffs. It's explained quite well here: http://www.alpinequest.net/en/help/v2/l ... statistics.
- The application also computes barometric elevations from pressure values if available. Pressure values are less noisy than GPS elevations, so it also results in a smaller gain using this method. You can export the pressure values in a GPX file (using an user setting, ask for more details if needed), but unfortunately you cannot export the computed elevations values, only the GPS elevation values are exported.

Let me know if something isn't clear enough or if you have any question
Best regards

[kepPNW]

Appreciate the response!

- The application does apply a noise correction algorithm when displaying stats on tracks. It results in a smaller gain, closer to reality than when computing raw elevation diffs. It's explained quite well here: http://www.alpinequest.net/en/help/v2/l ... statistics.

Yeah, that was the principle reason I purchased the app. I haven't found any other, for cellphones, that takes advantage of the built-in barometer like that.

- The application also computes barometric elevations from pressure values if available. Pressure values are less noisy than GPS elevations, so it also results in a smaller gain using this method. You can export the pressure values in a GPX file (using an user setting, ask for more details if needed), but unfortunately you cannot export the computed elevations values, only the GPS elevation values are exported.

Ugh! So the data are essentially locked within the app? That's seriously disappointing.

Shoot, waaaaay beyond seriously disappointing. Infuriating, really.

As I said, this was the reason I paid for the app. Is there any rationale, that you're aware of, for this design deficiency?

Data want to be free!

[Psyberia-Support]

No no nothing is "locked"!
I just meant that currently, it's not possible to export those values.
But it's planned for soon, someone else also asked if it would be possible to export the exact values used in the graphics.

[kepPNW]

I just meant that currently, it's not possible to export those values.
But it's planned for soon,

Wonderful news! I'll be promoting the hell out of this app, just as soon as that happens. As far as I know, there just isn't another cellphone GPS app that does that, and every one I've tried just records the raw GPS elevations in the GPX. (I do hope that'll be one of the supported export formats for the processed data?) My long-standing position has been that cellphones aren't up to the task yet, but knocking this one off will leave only the battery issues.

Thanks much... Karl

[kepPNW]

Just checking back to see if you've implemented that "enhanced" export capability? I recorded a track yesterday that, when exported, showed over 7000' of elevation gain. But your app showed a (far more correct) value of about 1300'. Would really like to capture that data in the GPX!

Thanks...

[Psyberia-Support]

I know it's not in the GPX format but as discussed here you can now export all the computed data (including barometric elevations) in a .CSV file.

I still plan to add options for the GPX export, but I'm not sure what I'll be able to add (barometric elevations are computed after lots of processing which make them incompatible with other data).

[kepPNW]

Hmmm, I did read that other thread following your prior cite, of course, and didn't see it "discussed" other than your stated desire to add that feature at some point. So, just choosing the "export CSV" option will now enable that data to escape?

I'm having trouble seeing the dilemma with the GPX export. Presumably the data (or their generation capability) exist, if you can squirt it out to CSV. Seems like a natural toggle to add prior to export for any format.

Appreciate your response! Still totally loving the app. Just wish I didn't have this problem getting at the displayed data. That is, in fact, the only thing holding me back from recommending AQ to every hiker I know.

[Psyberia-Support]

It seems that you didn't read until the end, because it's not a "desire" anymore since last summer (version 2.0.2c)
The application will apply various filters before getting the data from which it will compute stats and display graphics. This data is no more correlated with the original locations, so this data is not suitable to be exported in GPX...

[kepPNW]

It seems that you didn't read until the end, because it's not a "desire" anymore since last summer (version 2.0.2c)

Sneaky.

The application will apply various filters before getting the data from which it will compute stats and display graphics. This data is no more correlated with the original locations, so this data is not suitable to be exported in GPX...

Okay, well, I hate to say it but nothing in answer to either thread is very clear. I tried the CSV export, and ended up with these fields:

longitude - good
latitude - good
coordinate - Uses some funny character (Â) after each number, no apparent utility
altitude - meters, presumably raw?
geoid_height - meters, presumably massaged?
time - very large number with no immediately recognized frame of reference?
accuracy - horizontal measure in meters?
pressure - good

So, without yet making the effort to twist this from CSV into GPX, can you tell me if my interpretation of your fields is somewhat correct? Seems those values are indeed tied to specific coordinates, so why do you say above they're not?

[Psyberia-Support]

You went a bit too fast and didn't choose the right export format...
Bonus: I've just added the description of each exported column, let me know if something is not clear.

To go deeper in details: the application will not compute the stats and graphics based on all single original locations, but rather group them in "buckets" of locations, based on various criteria. This will smooth the results and reduce the computation time. For small tracks, you'll likely find 1 bucket = 1 location, so you'll be able to reconstruct the original track from the bucket locations, but it's not true for longer tracks. That's why I said that the stats are not correlated anymore with the original locations...

[kepPNW]

You went a bit too fast and didn't choose the right export format...
Bonus: I've just added the description of each exported column, let me know if something is not clear.

D'oh! You're right, of course. Chose the first CSV visible. I'm sorry for not digging deeper there.

To go deeper in details: the application will not compute the stats and graphics based on all single original locations, but rather group them in "buckets" of locations, based on various criteria. This will smooth the results and reduce the computation time. For small tracks, you'll likely find 1 bucket = 1 location, so you'll be able to reconstruct the original track from the bucket locations, but it's not true for longer tracks. That's why I said that the stats are not correlated anymore with the original locations...

Going to play with this today, thanks!