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Missing autogen buildings in Prepar3D


Staff member
FSDevConf team
Resource contributor
Hi all,

I thought I posted this information before, but since I could not find it back, let me do so again.

A while ago I was approached by a developer that he was missing certain autogen buildings in Prepar3D when generating the autogen with scenProc. So he asked if this was a bug in scenProc. This was around the time that I also found and fixed this autogen bug:

So at first I thought this might be another bug in scenProc, but the more I search, the more convinced I became that it is actually in a bug in Prepar3D itself. To prove that I made a simple test scenery of 25 x 25 buildings that are placed in a regular grid. All the buildings have the same orientation and the same size. So that way I can exclude that the oriention or size have any influence on this behaviour. When loading this test scenery in Prepar3D v4, you can see that not all buildings show, see the screenshot below. Even at the highest autogen density settings around 20% of them is missing. The funny thing is that if you load the same scenery in FSX, all 625 buildings show up nicely.

I have also attached the scenery file itself, in case somebody wants to see if they can reproduce it in their simulator as well.

My conclusion for now is that this is a bug in Prepar3D itself and I have not been able to find any workaround to let the buildings show. I have reported the issue on the Prepar3D forums to Lockheed Martin as well, but I haven't received an answer yet.

It would be interesting to hear if you see the same behaviour with the test scenery and if other developers maybe have ideas on how to work around this issue.



  • grid.zip
    3.9 KB · Views: 161

I am observing the same thing in my sceneries. I just have the feeling it is far more than 20% not showing but yours seems more scientific ;) Let's hope they do something about it!

In this thread some suggestions are given on reducing the effect. I haven't tested them yet.


In this thread some suggestions are given on reducing the effect. I haven't tested them yet.

Hi Arno,

The effect is caused by a setting in the Prepar3D .cfg file - the entry is;


If switched to =1, this brings back 100% autogen coverage, at the expense of course of performance. I'm not sure why they introduced this change, as it's not present in FSX, which naturally presents 100% autogen coverage if the sliders are set to maximum.

I learned of all this while doing scenery work last year for a major developer on a 50km square area of terrain, and noting the differences between the two platforms.

Thanks for the confirmation. I never bother too much with all those CGF settings, hence I never learned about this before.

If I read the information that was linked to in the other thread, it seems that LM added this option when they implemented the pop free autogen in P3D. When you disable the pop free autogen I read you also get the same behaviour as in FSX.. But it is still unclear to me why they added this batch LOD setting, while they could also have used the existing density slider to control it. Having two settings that kind of control the same thing sounds confusing to me.
From a fairly old post (2013) on the LM official forums:


The updates to the auto-gen system allow us to render greater numbers of buildings and trees without the same performance hit they used to have, which is what enables the pop-free auto-gen. When the new system is enabled, scenery tiles are loaded at the LOD specified by that config option. The numbers go from 9 to 1, with one being the highest. Don't set it to zero, as that might blow up in some areas. As a few folks have noted, the auto-gen directly below the plane is a little less dense by default, because the system only loads the second highest LOD. Experimenting with the LOD in the config just provides another way to adjust the density of scenery loaded, but since both the slider and the config option do similar things, we left one in the config for our more adventurous users to play with if they wished. Be warned that increasing that setting to 1 will in many cases double the number of buildings and trees again, making it potentially very expensive.

Zach Heylmun
Software Engineer - Prepar3D Team