Aircraft LOD Distances

MajorMagee

SOH-CM-2022
I should probably know the answer to this, but is there a way to adjust the distances where the Aircraft LODs change like you can for the scenery and terrain?
 
After a lot of searching and experimenting it seems to be that MS chose to hard code this into the program, and it does not appear that they provided any external calls to a settings file to let you change it. :banghead:

Anyone else been down this rabbit hole before? AnKor?
 
As far as I can tell the trigger to change LOD seems to be the size that the aircraft is being drawn on the screen. Perhaps it's based on the number of pixels?

If I change the FOV value in AnKor's d3d8.ini to something lower, so the external views are more magnified, then the distance away from me that the higher detail LODs are being show goes up.
 
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I am not well versed on the intricacies of the config. settings but I do think LOD distances are determined by the size of the object.
If you have gmax, you should be able to check this by creating two simple models (say, a cube etc.) of different size (make the size difference significant!) and two or three LODs each. Give each LOD a different colour, eg. LOD_100/Blue, LOD_60/Yellow and LOD_30/Red. Place them on a facility of your choice and see what happens at various viewing distances. If size is the defining parameter, you should not see the same LOD pop up for both cubes at the same time/viewing distance.

So, if this works out and if there is no config. setting for LODs, I think the only way to alter the distance at a certain LOD kicks in, is by hexediting the .M3D file (if you do not have the source file) and alter the LOD number. Look for LOD_xxx (where xxx is a number) entries in the file. At least, that is how I code LODs in my models.
 
Hi Guys,
I think you'll find that CFS3 is like Fs9, in that the the sims do not use LOD's in the same way CFS2 does, FSX does not use LOD's at all.

When constructing for CFS2 you can specify when a LOD will be displayed, and it will do just that. With the other sims, you build the LODs and the sim will decide when it's displayed. Frosty, I take it you are changing just the order in which the LODs will be displayed, not when?

When they get displayed is, as you say, hard coded into the sim, it will choose when to display another LOD. It may be clever, but I bet it's something simple, as you say, like the number of pixels to be drawn, which will trigger the next LOD. Having said that, the suggested test is a good idea, but if there's several variables to account for, it may be very time consuming.

What's the aim of the info? Setting up mass combat or?

Cheers

Shessi
 
Yes, the reason was to try adjusting the LOD distances as a way to reduce stuttering / fps drops.

I've tried hex editing the LOD names in the m3d file yesterday and it seemed to have no effect at all.
 
... Frosty, I take it you are changing just the order in which the LODs will be displayed, not when? ...

No, I did mean 'when' :adoration:.
The way I see it is this: Assume we have a model of a barrel that has 12 sides at LOD 100, 8 sides at LOD 50 and 4 sides at LOD 10 (that's not a very round barrel at LOD 100 but assume so for the sake of the example). If I find in-game that I can see either see the transition between LOD 100 and LOD 50 too clearly (LOD popping) or if I find the barrel too angular at a certain viewing distance, I could rename LOD 50 to, say, LOD 35 and the transition takes place at a greater distance. In my book (but perhaps not in a game designer's - I am just a hobbyist) that would be the same as adjusting the viewing distance. Unfortunately, it's a bit of trial and error, as there no indication how much distance the lowering the LOD equals.
In any case, it would result in LOD 100 being displayed for a longer time/distance. Changing the order would mean seeing LOD 10 displayed before LOD 50. That can't be good :adoration:.

Which all reminds me that I still do have to adjust the barrel models in CFS3 because some of them are too angular in the UI, lol. Something for the next ETO update...
 
Ok then, I suppose in this case, what displays when has the same result..lol.

I think you can safely say it will be numbers of pixels which will trigger the next LOD, if it's distance you want to know then the trial will show that. One sure way to hold the display of a higher detailed/poly-ed LOD would be not to have a lower poly-ed version of that item, force the b*gger to use it...ha!

Do higher poly-ed barrels really have a huge impact on FRs? or is more important to have the actual ac LOD-ed. Maybe have a trial, one will the ac with LOD-ed barrels and one without, see the FR differences......

Munitions and weapons are quite low on detail in real life, and in CFS2 I've found that LOD-ed munitions really makes little or no FR difference at all, I wouldn't know about CFS3 as it's capabilities are much higher than CFS2. If it make little or no difference then take the lowered poly-ed LODs out and have glorious eye-candy gun tubes...;)

Cheers

Shessi
 
Ok then, I suppose in this case, what displays when has the same result..lol.

I think you can safely say it will be numbers of pixels which will trigger the next LOD, if it's distance you want to know then the trial will show that. One sure way to hold the display of a higher detailed/poly-ed LOD would be not to have a lower poly-ed version of that item, force the b*gger to use it...ha!

Do higher poly-ed barrels really have a huge impact on FRs? or is more important to have the actual ac LOD-ed. Maybe have a trial, one will the ac with LOD-ed barrels and one without, see the FR differences......

Munitions and weapons are quite low on detail in real life, and in CFS2 I've found that LOD-ed munitions really makes little or no FR difference at all, I wouldn't know about CFS3 as it's capabilities are much higher than CFS2. If it make little or no difference then take the lowered poly-ed LODs out and have glorious eye-candy gun tubes...;)

Cheers

Shessi

Not sure what you mean by "force to use it". I think the whole point is that we cannot find a way to force CFS3 to switch LODs at a by the modeller predeterminded distance. Or put differently, we don't know what the relationship / ratio between viewing distance, LOD number and model size is. In that respect CFS3 must be very different to CFS2. You mentioned earlier that it is possible to tell CFS2 when to switch LODs. How is that done? I can enter a LOD node in a gmax model but I have no idea to what viewing distance that relates. For me that is trial and error - and that is what I meant by lowering the LOD number if the ingame result is not satisfactory. But if there are other ways to model, I 'd be happy to learn from others.

And my apologies, 'barrel' in this case did not refer to a 'gun barrel' but an 'oil barrel / drum' model I made for use on airfields (which are also shown in the UI). It was just an example to illustrate my point on the whole LOD/distance switching-thing. Indeed, such small items as gun barrels do not have much impact on FR.
 
Yes, I think we're saying the same thing.......

Sorry, assumed gun barrel, but no matter, as you say, the same principle applies.

Force a LOD. This is only blunt force and not elegant, if you do not have any LODs the sim will use the only one, therefore if you do not want a too lower/poor quality LOD version to show up, then either replicate the previous higher detailed one or restrict the number of LODs. The sim will then be forced to use either the next numbered LOD,which being the same detail, means you get the same look, of if there is not another lower poly LOD it will have to still display the previous higher detailed one.

I know this is not what you really want, you want the holy grail of LOD size/distance display criteria relationship. As said the trial/test will have to be done to work out what/when another LOD is triggered, but if it is more complicated as including something like overall number of polys displayed or FRs, could be difficult to test.

When compiling for CFS2, as in FSDS, it gives you a choice numbers of pixels and distance that a LOD displays. Now I don't know how accurate that is...(how do you measure the number of polys an item is using on the screen??? :dizzy:), but you can affect the LOD changes.

Cheers

Shessi
 
LODs

LODs are determined in the source file and designated by the modeler. Each successive lower LOD has fewer and fewer polygons - meaning far less detail and realistic shapes. The modeler determines how many LODs s/he wants and the number of polygons in each. MS then displays the LODs given two factors. First, distance: as the plane moves further away the LODs become lower. Second, in the config file depending upon the aircraft display number you select will in turn determine the maximum LOD that can be displayed. The lower the aircraft display number the lower the LOD that will be the highest LOD displayed. Not sure how one can manipulate the distances the LODs are activated it may be hard coded or in one of the various dlls. I know that the distance for aircraft to be displayed on the radar is determined in the pilots dll, so maybe too the LODs could be fiddled with.

Hope this helps - oh in the aircraft SDK MS did offer suggestions on the polygon limits, but we have surpassed these recommendations many years ago.

TSK
 
I also tried changing the max model LOD level in the config file, as well as lowering the aircraft detail setting from 5 to 1 and didn't see any change in game, so decided that they didn't implement these as adjustable functions before the game was released.
 
LOD

The impact on appearance really depends on the model being used. The stock planes viewed on 1 or 2 show the differences.
 
I looked at this a while ago and found on Aircraft image quality slider set to 2 or 1 the best you'd get would be LOD90 (if the model has that LOD.) Not every model has a full set of LODs
 
Interesting, I was looking at the AvH P-80 that has LOD 10, 25, 50, 70, 90 and 100. I suppose I should have tried it with other aircraft to confirm.
 
With CFS2 LODs changing isn't fully set by distance. Object size (both physical and polygon count) seem to have an effect. It also changes if your viewing an aircraft/object in Free Flight or during a mission so aircraft/object loaded for the mission also have an effect.

In Free Flight the game don't really like to change LOD while during mission the changes can be noteable if you look at somthing big like the B-24D.
 
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