#1965 Space Oddyssey "monolith" phenomenon

[Rado]

FG2016.4, FG2017.1.1, FG2017.1.2, FG2017.1.3
OS Xubuntu 14.04, Lubuntu 17.04, Win 7 Enterprise
Nvidia GTX750 2 GB graphics
Intel K2550 CPU
8 GB RAM
When I flying in high altitude over FL500 toward dark side of the Earth , there is black rectangle on the horizont :

[Thorsten Renk]

It's a problem in the skydone shader numerics, triggered by a combination of altitude, weather conditions and lighting. Seems to be more prevalent with Basic than with Advanced weather, so it might also have to do with how BW sets the high altitude atmosphere visuals.

I've been looking for it a couple of times, but couldn't identify the root cause, I assumed clamping color channels to [0:1] would fix it, but it did not. Out of ideas at this pointm

[Edward d'Auvergne]

The ideal for solving a bug would be to be able to easily reproduce it. Then the solution only takes a few minutes (in most cases). If you could come up with a set of command line options that start fgfs in exactly the same place, date and time so that the black rectangle is absolutely always visible, then that would be invaluable.

[Rado Sutto]

I tested it again and found, that this is probably nVidia related problem.
Test condition :
position LZIB, altitude 55000 feets
UTC 17:23
bearing 100 degree

On AMD FirePro graphics with Catalyst driver Monolit doesn't exists.

[Rado Sutto]

Monolit is visible over 54000 feets, not affected by shaders preset, but only with ALS on. Without ALS is all OK.

[waldo kitty]

please follow this topic on the forums, too... i've reproduced the "fallen monolith" and can reproduce it at will... instructions are in the topic on the forum...
https://forum.flightgear.org/viewtopic.php?f=37&t=31880

[Thorsten Renk]

Seems to have been a numerical issue- hopefully gone now.