Graphical errors when aberration is set to very high

[Atque]

If one changes the upper aberration limit from 5 to something very high, say 1000, which better corresponds to the didactic scope of the exaggeration feature, graphical glitches occur when zooming in. An example of this is shown in the screenshot below, where some kind of clipping affects the stars on the left third of the image.

For this reason, the upper aberration limit is currently locked to 5, which makes it barely noticeable from Earth, unless the FOV is very small. Ideally, it should be possible to multiply aberration by 1000 and still have no clipping.

See the discussion below for further details.
Originally posted by @Atque in #4741

[github-actions]

Hello @Atque!

Thank you for suggesting this enhancement.

[henrysky]

I think the clipping is caused by zoning of the star catalogs. With very high aberration like x1000, stars are pushed outside of their zone, hence the disappearance when zoomed in (a small FOV screen overlaps less zones than a large FOV).

[Atque]

Ok, does that mean it's practically impossible to solve? @gzotti do you remember how it looked around 2021 (aberration introduced, old star catalog)?

[gzotti]

Oh, I never thought of the zoning issue on that!
@Atque you could just go back to 24.4 (git checkout v24.4) or earlier and compile to have a look. The zoning scheme was also used earlier, just with more errors.
But if one builds with upper limit 1000 and then just wheels through the setting, observing the star moving but still near screen center, I won't know why it should really suddenly vanish. It may be some threshold in projected screen space, but as said, I did not further investigate.

[Atque]

Could one solution be to simply apply aberration to the zones?

[gzotti]

If that's the actual cause, adding aberration to the zone vertices before testing zone vs. screen may probably be a solution. @henrysky ?