You have stated repeatedly in this and other forums that the 'cloud of doom' is caused by 'faulty or corrupt' cirrus cloud texture (namely the cirrus_overcast03.bmp texture) however this is not correct. I've freshly installed FSX from the DVDs and, after running OpusFSX, still see the problem clearly. In this case my cirrus_overcast03.bmp is certainly not corrupt! The reason for the phenomenon is due to the way FSX is coded to handle visibility layers but I've some observations to share with you...

 

Its true that the solution you offer to replace this texture with your own modified one DOES remove the cloud of doom, however it has a rather (IMHO) jarring side effect. This side effect is that FSX can no longer cap reduced visibility layers with a 'topping'; resulting in rather abrupt visibility changes as you climb out of thick fog, i.e. poor visibility (or fog) where you cannot see the ground clearly then suddenly the ground can be seen (more or totally) clearly. Topping the poor visibility layer with cirrus_overcast03.bmp prevents this happening; think of it as closing the lid on the 3D region of poor visibility. Of course there is a visible downside to this topping and that is most apparent when the fog layer occurs in hilly or mountainous regions; now you see z-buffer fighting between the layer and the hills. So neither solution is totally without issues :(

 

Finally, I've just tried 5 weather engines in quick succession - ASE, REX ODE+, FSRealWx, OpenClouds and Opus. All of the engines result in FSX using the cirrus_overcast03.bmp file to top low visibility layers (unless you switch it off in the relevant Weather Engine settings - and don't forget this simply replaces cirrus_overcast03.bmp with a totally transparent layer hence the problem above returns much like with your own solution) BUT none of them EXCEPT Opus has given the cloud of doom effect (at least in the tests I ran). Note I checked that all had exactly the same METAR for the airport I was located.

 

To make testing easier I simply replaced cirrus_overcast03.bmp with a 512x512 totally black monochrome bitmap; this makes it very easy to spot when the bitmap is being used (and also leads to some spooky effects as you move through it!). You will see that the cloud of doom occurs only when using Opus. P.s. make a back up of your current cirrus_overcast03.bmp if you want to try this!

 

Hope someone finds this useful...

Andy

Hope someone finds this useful...

 

Thanks, Andy. Very interesting.

 

You will see that the cloud of doom occurs only when using Opus.

 

Can anyone else verify this?

 

Hook

Only certain engines use the cirrus to top fog layers, we don't so it has no effect.

 

I have heard reports of people getting the cloud of doom on FSX systems before OpusFSX. Our WE does not select or position bitmaps. If it is more visible in OpusFSX it is probably because we are providing more detailed weather.

 

Out of interest have you tried it in Opus when you disable the cirrus?

 

Regards

Cheryl

Only certain engines use the cirrus to top fog layers, we don't so it has no effect.

 

Out of interest have you tried it in Opus when you disable the cirrus?

 

Thanks for your reply. I think there are two separate issues here and maybe I should have made more of a distinction, one is general to all weather engines the other I think is specific to Opus:

 

1. The use of the 'special' cirrus layer (i.e. cirrus_overcast03.bmp) to top fog.

 

I was under the impression (and my tests appear to support this) that FSX *always* tops fog layers with the cirrus bitmap. The weather engine (internal or external) asks for reduced visibility and FSX automatically tops it. The 'work around' from the 'mountainous area issue' that most external weather engines use (including Opus) is to replace the cirrus texture with a fully transparent one and so it removes the mountain issue (and, as I didn't mention, the sometimes clearly visible 'white' line at certain altitudes even in flatter geographical areas). I repeat, the unwelcome side affect are possible abrupt changes in visibility when changing height. In extreme cases you can descend on a lovely clear day and suddenly find yourself in a fog bank - this is caused by the area of low visibility now having no 'lid' and so when looking down cannot be seen. Take your choice of what is less satisfactory to your personal flying!

 

2. Cloud of doom.

 

If you *don't* replace the default cirrus texture with a transparent one then Opus is the only engine which appears to create the 'cloud of doom', i.e. a cirrus layer (not a genuine one but a layer topper!) seemingly always present at a high altitude. If you follow your instructions and replace the cirrus bitmap with your own then of course this effect is removed but at the expense of the abrupt change in visibility described in point 1. (Pedant: Opus always creates the cloud of doom, its just that you cannot see it when using your replacement texture).

 

All these effects are much clearer (no pun intended) if you replace the cirrus bitmap with a black one (as I described above).

 

In regard of your question, I believe I tried with both the cirrus layer enabled and disabled in Opus but I will re-test to make sure.

 

HTH

Andy

 

p.s. all tests done with a fresh FSX Acceleration install and OpusFSX v2.40.1 Beta (demo mode).

 

p.p.s. On re-reading my posts it may appear that I'm negative towards Opus, this is not the case I find it a very good weather engine in general, very quick and easy to use (and I've tried a few!) but my problem is with the fix you've suggested for the 'cloud of doom' - however this 'fix' is used by more than just Opus.

I have heard reports of people getting the cloud of doom on FSX systems before OpusFSX.

 

I thought I had too, Cheryl, but I am unable to find any reference to it now. There is one mention by Chris of Hifi about the doom cloud compression, but it doesn't appear to refer to the same problem.

 

A search for "cloud of doom" returns no results; and the "of" is removed. A search for doom does have results, but mostly concerning Opus (the sole exception is mentioned above). I remember a thread talking about an "umbrella" of clouds that follow the plane, but I can't find it now. Perhaps someone else will have more luck with a search, or can describe the problem on another weather engine.

 

I suspect part of the problem is using an option in Active Sky to Enable Stratocumulus Simulation and/or using the Stratocumulus-style cirrus graphics. I no longer use either.

 

Hook

Hi Andy

 

I don't consider your comments negative. It is the individual weather engine that tops the fog layer with a cloud layer not FSX. Regarding the vis, all this has been discussed on the Flight1 forum, it is to do with visibility layering in each weather cell which is currently uncoordinated but will soon be addressed with our weather smoothing enhancement.

 

We have just introduced the cloud of doom here on one of our systems when we installed new textures. I believe it can happen in a fresh install of FSX. We have just provided a solution to the problem.

 

The reason that the clouds act the way they do around hills, trees etc. is that the clouds are actually invisible 'boxes' filled with texture maps. When these polygon boxes interact with other polygonal surfaces (in this case the terrain) you will get clipping occur. It happens in all 3D games where polygon based objects are used, rather than particle or true volumetric shaders.

 

Hi Hook

 

We labelled the issue the 'cloud of doom' but others call it the 'static cloud layer' etc.

 

Regards

Cheryl