Each CSV has a different GPS location??

[Lindsaybev]

I am just learning about the flight records, and am a bit confused about the three CSV files I can extract from the folders which come from my tablet.

I am using the DJI Flight Log Viewer to download my flight path in CSV format. The confusion comes from seeing different values in the Lat and Long sections of the flight log.

I have 3 different CSV files: One from DJI Flight Log folder, which comes as a .txt file. I put that in the viewer and in the viewer I download to CSV. Another I get straight from the Litchi app as a CSV. The third I get from uploading the CSV from the Litchi app and then downloading it as a CSV. (I did this to see what would come out, not to be redundant.)

Each file is the same size, but the values of the lat and long start to change a bit. And it is not from rounding up and down.

Does anyone know why this is and which one is the "most" accurate version of the actual flight??

Thanks! Everyone is always so helpful. I do spend so much time trying to learn. It seems the more I learn, the more questions arise! But that is a good thing. Keeps me young....

 

[Fly Dawg]

but the values of the lat and long start to change a bit.

By a bit, what are you exactly referencing. If all three are the exact same flight they should be "basically" identical. This could also depend on the conversion decimal values. We would need to see the actual files to show what you are referring to.

 

[Fly Dawg]

If you are seeing wide variations in co-ordinance's over time, this could also be related to the latency in transmission vs recording. I don't recall what the sample rate is off the top of my head, but you can also take that in to account. You can pretty much be assured regardless of which data set you use the accuracy will depend on a few variables, but will generally be within the tolerances of the GPS reception vs the FC calculations. Bottom line is any of these are close enough for the purposes needed. I wouldn't be concerned with a few decimal point deviations. Also, this will vary from aircraft to aircraft and firmware versions. All the data available may not be transmitted that is not supported.

 

[Lindsaybev]

After looking again at the two from Litchi, they seem to be the exact same, as I would expect.

The changes mostly take place at the 4th decimal place between Litchi and DJI files. Sometimes the Lat is different, sometimes the Long, sometimes both. Here are some examples:

Thanks for looking. Not sure how to upload the actual file.

 

[Lindsaybev]

If you are seeing wide variations in co-ordinance's over time, this could also be related to the latency in transmission vs recording. I don't recall what the sample rate is off the top of my head, but you can also take that in to account. You can pretty much be assured regardless of which data set you use the accuracy will depend on a few variables, but will generally be within the tolerances of the GPS reception vs the FC calculations. Bottom line is any of these are close enough for the purposes needed. I wouldn't be concerned with a few decimal point deviations. Also, this will vary from aircraft to aircraft and firmware versions.

Thanks for all your help, FlyDawg. You are always attentive to this forum, and I am grateful. I guess I was just hoping for a bit more accuracy because I wanted to work with some people who run a land parceling company. We'll see what transpires!

 

[Fly Dawg]

Completely normal......You will have plenty of accuracy for land surveys. You wont get much better. And as I mentioned there are other variables involved, so not to be overly concerned about a few decimal points.......Take a few of those closer points and create a GE profile, you will see what I mean by the slight difference is miniscule.....

 

[Meta4]

After looking again at the two from Litchi, they seem to be the exact same, as I would expect.
The changes mostly take place at the 4th decimal place between Litchi and DJI files. Sometimes the Lat is different, sometimes the Long, sometimes both.

Check the home point location to see if there's any difference there - it would be really surprising if that was different.
Since the logs are taking the same data from the same source, it would be surprising if they are different for the same point in time.
Check that you are actually looking at the same time point and not just the same line number in a spreadsheet.
For example, does one start recording before launch and another start when the flight starts?

 

[Fly Dawg]

Check that you are actually looking at the same time point and not just the same line number in a spreadsheet.

Agreed, if I am not mistaken the logs are sampled at 100ms intervals. So they can vary slightly, and I mean ever so slightly from the other files, simply due to latency.

 

[Lindsaybev]

So very intereting...and COOL! I have been in Google Earth Pro all day, doing pre-flight missions. I love it! Thank you so much for all the information. I have started a running file to keep it all at hand!

Thanks a million Fly Dawg and Meta4! I have a great deal of information to bestow at this point. And a lot of practice ahead!

Hey! Maybe at some point in the near future I will be able to actually give advice on the forum instead of eating from it like a piglet! lol.