Flashing vertical lines

Any issues, problems or troubleshooting topics related to the Prepar3D client application.
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Postby jtstevens » Tue Apr 22, 2014 6:02 pm

Many thanks for version 2.2: this sim keeps getting better and better!

However, one issue is that I frequently get flashing vertical lines when under high GPU load, especially with cloud shadows enabled. They often appear immediately after panning the view, and only stay there for a fraction of a second, but are very distracting. I started seeing this problem after upgrading to 2.2. I don't think it's hardware related, as I experienced this on two GPUs (a Titan Black and my older GTX 670), and others are experiencing the same issue (see this thread on avsim: http://forum.avsim.net/topic/439924-flashing-vertical-lines/ ).

This video (not mine) shows the problem, between 7:28 and 7:29 in the center of the screen and between 7:41 and 7:42 slightly up and to the right of center: http://www.youtube.com/watch?v=j90H9vqkTWQ

However, in my case the spikes appear more frequently.

It's possible that I'm simply overloading my GPU, but the spikes can appear when the frame rate is pretty good: 25-35 fps. Is it expected that a GPU will produce artifacts even when it can sustain a reasonable frame rate, and if so, is there any workaround? I would be perfectly happy with this frame rate in order to enable the wonderful cloud shadows or high AA settings, but the spikes spoil the immersion. Also, in previous versions I would often get a lower fps (in a GPU-bound situation) without these artifacts, so I wonder if something has changed in 2.2 that makes them more likely.



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Postby kandoit » Tue Apr 22, 2014 7:08 pm

it looks like tearing of video segments

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Postby XenoRad » Wed Apr 23, 2014 3:32 am

I am also having this problem with a new ATI R9 290x and a recent install of P3D.

I ran some tests last night and found the following:

- the lines appear immediately but with varying frequency over areas with autogen buildings;

- the lines are more likely to appear at medium-long range;

- the settings that affect this are autogen density and shadows (shadowmap quantity + building shadows - cast/receive);

- with shadows disabled the lines don't seem to appear at all;

- with autogen buildings disabled the lines don't seem to appear at all;

- other graphics settings seem to have very little if any impact on this issue (I can get them with pretty much everything turned down and over 100 FPS);

- except for the fact that the lines are more likely to appear in populated areas (more demanding due to the number of buildings present) from my results the is no visible correlation between framerate and this issue;

- deleting the shader files and allowing P3D to rebuild them does not solve this problem;

- the lines happen in an area where I get 45-50 FPS with a max GPU temperature of 73 ºC and equivalent CPU temperature. The video memory amount used varies between 1.4 to 2.7 GB as the flight progresses;

- my system is not prone to glitching in other applications/games including demanding benchmarks.

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Postby dude1220 » Wed Apr 23, 2014 4:04 am

I also have this problem since 2.1. It usually happens when my GPU is at full load. I don't think it is due to my GPU being overheated because I do not have similar problem in other 3D apps/games at full load, and I always keep my max GPU temperature at 65C, which is way below the recommended max.

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Postby MarkSC » Wed Apr 23, 2014 7:18 am

I too have this issue with my 780. It's not temp related. It never occurred until 2.2. However, 2.2 allowed me to turn autogen and shadow settings up, so I'm sure that's playing a role in stressing the GPU. There are lots of other programs I run, though, that equally stress the GPU and don't cause the vertical spikes.

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Postby NN_Avirex » Wed Apr 23, 2014 12:11 pm

I have had this problem a lot with 2.1, less with 2.2.

It's like if autogen buildings had an infinite height for 1/100 second.

It happens with my 770 4Gb (last regular driver),at low temperature (between 50 and 60° celsius).

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Postby Pastaga95 » Wed Apr 23, 2014 5:09 pm

I can see the same flashing vertical lines.

I have not seen it with the V2.1 but the building autogen was set to low to avoid VAS crash.

With higher autogen and complexity settings, this now for me much more visible on V2.2.

My AMD 7970 graphic is not especially stressed or hot (63°C) when this problem occur on city areas.

My felling is that the build is falling from the sky to the ground.

Not a real big issue, taking in account the massive improvement of the V2.2 for the stability.

However, would be great if the V2.3 bring a resolution here.

Again many thanks to LM developpers for their great work!


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Postby XenoRad » Mon Apr 28, 2014 4:28 pm

On rare occasions such lines stretch out in other directions rather than just vertically and end up covering up to a quarter of a screen. It would be good if we can get some information/confirmation from someone at LM regarding this issue.

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Postby BG2518 » Mon Apr 28, 2014 6:40 pm

Same experiences here and would love any tech feedback from LM on this.

BG2518 - Bob.

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Postby gpf3m » Mon Apr 28, 2014 7:43 pm

I have it as we'll. However, If I set autogen buildings to medium or less, the symptom disappears.

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Postby vgbaron » Tue Apr 29, 2014 1:40 pm

Turning down settings to eliminate artifacts is a good idea.


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Postby XenoRad » Thu May 08, 2014 6:30 am

Except it means treating the symptom and not the problem. I'm giving this thread a bump and suggest others do as well if they wish for any feedback from LM. Even a small "we're investigating this" would help.

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Postby Nullack » Thu May 08, 2014 3:08 pm

Im replicating this bug too. I stress tested my gpus with artifact scanning in furmark and no artifacts were produced. For sure an LM or gpu driver problem - Im on nvidia 337.50

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Postby mike2060 » Sat May 10, 2014 4:10 pm

I get this too.

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Postby Saghaard » Sat May 10, 2014 4:59 pm

Same for me.

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