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rt-bishop / Look4Sat

Open-source satellite tracker and pass predictor for Android, inspired by Gpredict
https://play.google.com/store/apps/details?id=com.rtbishop.look4sat
GNU General Public License v3.0
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Satellite pass radar view showing odd artifacts since ~v3 #94

Open ryandzink opened 2 years ago

ryandzink commented 2 years ago

I am not sure if this is an isolated issue but I am often seeing pass arcs look very strange, starting roughly since v3 of the app was released a few months ago. This never seems to happen when just opening the radar view from the pass list, only when already on the radar view and returning to it from another app or when unlocking the phone when it was previously on this radar view.

I am using a Pixel 5a on Android 12. Here are several examples of what I am seeing, it happens ~5% of the time, but enough to be noticeable.

Screenshot_20220611-092821 Screenshot_20220617-115305 Screenshot_20220618-140954

rt-bishop commented 2 years ago

Hey @ryandzink! Thanks for reporting this and sorry for the late response. I've been trying to reproduce this issue over the past two weeks on several devices and didn't have any luck.

Although this issue is known to me and I observed it several times even when v2 of the app was out, the reason for this stuff happening is unknown to me. I tried to investigate a bit at the time and found out the same thing as you did - that it only happens when you unlock the screen on the radar screen after the phone is idle for some time or bring the app back to foreground again after some time of idling. At first I thought it has something to do with the data calculations and the app timer, so to avoid that I forced the app to go back to the main list once the observed pass is finished and also made the satellite track only be calculated once, the moment radar fragment is created and then reuse that component instead of recalculating it. It then stopped happening and I though that it's gone for good.

Several months ago I randomly observed very similar issue with either weird trajectories like you have or complete screen freezes. I went to get some more data on that sat's TLE to https://www.n2yo.com/ and GPredict and observed very similar behaviour - either bad data, freeze or crash. So I contacted Gpredicts devs and shared this info with them. By the time they responded the bug was gone, and the data was shown correctly in n2yo/GPredict and the app. So I was adviced that this was probably connected to the faulty TLE data from the provider, or maybe only the partial data reported after the satellite launch but before it reached the final orbit.

Not sure what else to add as I can't fix something I can't reliably reproduce. Let's probably keep it open for a bit in case anyone else encounters a similar issue.

ryandzink commented 2 years ago

This is very interesting. I can reproduce it within a few seconds on my phone very reliably. Let me try clearing my cache, etc. and seeing if any of that has any effect.

ryandzink commented 2 years ago

OK, that didn't have any effect. I cleared cache and it is still happening. For reference I'm using a Pixel 5a and Android 12.

MrARM commented 2 years ago

Can also confirm this bug happens on my Samsung Fold 3 running android 12, it seems to happen while I'm using the pointer for extended periods of time.

ryandzink commented 2 years ago

I'm not sure if this most recent screenshot might point to a root cause, it seems like the pass is trying to draw on a circle that is offset from the radar circle...

Screenshot_20220702-102432

dl3jop commented 1 year ago

I can reproduce this issue reliably by choosing the pass view and putting the app in the background, most of the time when I reopen the app from background, the view shows these artifacts.