Lod bias CLAMP vs ALLOW

[Guest]

I've always been told that I should use CLAMP for FSX and not ALLOW. Why was that again? Because I found out that using ALLOW and then a Lod bias of something like -2.000 actually SHARPENS everything in FSX a LOT...! So I am wondering why everyone is advicing to use CLAMP...? (

 

(EDIT This is not about the LOD_RADIUS in the FSX cfg but about the Lod bias setting in nVidia Inspector!)

 

 

[William J.S.S 173]

I am unsure about this whole subject also.

 

I use LOD 5 to 5.5 in my FSX config, and would like to know if and what this would allow with my NI settings.

[Guest]

I am unsure about this whole subject also.

 

I use LOD 5 to 5.5 in my FSX config, and would like to know if and what this would allow with my NI settings.

 

Ah, that's another kind of LOD... You are talking about the LOD_RADIUS setting in the config which controls how far you will see specific things in FSX. I am talking about the Lod bias in nVidia Inspector for nVidia GPU's... Different story. ^_^

[William J.S.S 173]

Ahh...I see.

 

While I have a Nvidia GPU, I am still a little loss as to still what this does. Looks like I have a lot more reading to do about something I still don't understand.

[vipgroup 3]

While you are talking about LOD, is there a way to increase the distance at which AI textures are visible? Is there any setting in the fsx.cfg that globally impacts this, or is it set in the mdl of the specific ai aircraft when they are designed? Sorry if this is a side issue to the topic, but J Van E, your reply seems to indicate you might have knowledge of the whole LOD issue.

 

Regards,

Kenneth.

[quadraspleen 7]

you tweaker, you Jeroen :smile:

 

From TweakGuides.com:

 

Texture Filtering - Negative LOD Bias: LOD is the Level of Detail, and in some games you can alter the LOD Bias using various settings to sharpen details on screen. In such cases, you should set this setting to Allow, however note that altering LOD Bias can introduce aliasing (jaggedness to lines and edges) and shimmering. Since Anisotropic Filtering can also improve the sharpness of images without adding to aliasing, I recommend that you change this setting to Clamp for games in which you use any level of Anisotropic Filtering to give you better overall image quality.

[Johan_Dees 84]

Jeroen, interresting at least.

Do you get more shimmering ? as stated above?

 

I tried it but didnt saw much difference.. will try again tough.

[Jim Young 2,356]

I tried it but didnt saw much difference.. will try again tough.

 

Look for fences....

 

Best regards,

Jim

[molleh 451]

Interesting. How does Allow/Automatic look as compared to manually setting -2.000?

[Guest]

Well, all I see with ALLOW and -2.000 is sharper pictures and hence also more (tiny little trees) in the distance.

 

I wonder if this CLAMP idea simply is a leftover from the days when 1280x1024 was a VERY HIGH resolution and FSAA 4x was ENORMOUS...! Maybe the much better possibilities of new hardware (far higher resolutions, much higher FSAA settings) have eliminated the need for clamp and maybe Allow can be used even with settings like -2.000 (maybe even more, haven't tried). At a certain moment you might get pixelation indeed but with nowadays resolutions and FSAA you won't get it as soon as you would a few years ago.

 

I unfortunately didn't have the time to actually test this with a full flight but I did fly around a little after taking the screenshots and I didn't notice shimmering. Anyway, I think it's worth investigating. I don't think anyone would mind more crips gauges in their planes! The examples I posted speak for themselves: specially the higher sharpness in the VC is worth it: that sharpness is in effect on everything so also the GNS 530 I have.

 

To be continued. ^_^

 

EDIT

O yes, concerning the quote from Jake from TweakGuides about the use of CLAMP: as you can see in the second screenshot I posted there is NO difference at ALL between CLAMP and ALLOW when you look at the groundtextures, so Anisotropic filtering still does its job perfectly well.

This means that anisotropic does NOT make things sharper as ALLOW can do: anisotropic filtering makes the groundtextures sharper (things you see at a certain angle) while Allow makes OTHER things sharper.

This makes that quote from TweakGuide a bit odd... the relation that TweakGuides sees between using anisotropic and allow or clamp is not existent. Yes, they both sharpen things but in a none related way, so using anistropic INSTEAD of Allow, as TweakGuid suggests, isn't a wise thing. You are better off when you use both! And with current hardware that might just be possible without obvious side effects... but that has to be tested.

[Guest]

Loading FSX with -2 right now! Fingers crossed :rolleyes:

 

Fingers crossed here too. Obviously it's a YMMV thing, haha! What I forgot to say: did you type in that -2.000 number or select it from the dropdown menu? Typing it didn't work for me: I had to select the number from the dropdown list, so if someone can't get the number entered or working, select it from the dropdow menu,

 

O and btw: -2.000 might not be the best number. -3.000 may be even better but maybe then you do get too many pixels and hence shimmering. What I am trying to say is that the right number might be system dependant. If someone does get shimmering -1.000 might be a good compromise. In short: tweak and tweak some more! ^_^

[Guest]

Well, unfortunately, I'm not seeing any changes with both -2, -3 or clamp. I made 3 bmp shots, and all 3 look to my eyes exactly the same.

Jeroen, are you maybe using some tools like ENB, FXAA, SweetFX or similar?

 

Hmmmmm.... Odd. As I said I 'discovered' this setting in another game and in both games changing to Allow and an option of -2.000 clearly makes a difference (as you can see on my screenshots). I do not use ENB or ANYTHING like that anymore nowadays. So in that regard FSX is 'vanilla'. Hm... so you changed to Allow and then... selected -2.000 from the dropdown menu? Or did you type it in? It's a pity I won't be behind my FSX PC for at least a day now... Bummer. I will check and if needed post my nVidia Inspector settings tomorrow. Maybe some other settings has an influence too...

 

As you said in that other topic: there are just too many settings... ^_^

[Guest]

Not the textures, and not the NGX cockpit, but trees.

 

No, you won't see difference in the ground textures (which are sharpened by anisotropic filtering) but you SHOULD see sharpening in the VC. However, I do notice in my own screenshot that for instance the angle of attack indicator stays EXACTLY the same on both shots but the numbers on the Airspeed indicator are CLEARLY better. So maybe it only affects certain texturer or gauges... and maybe the NGX doesn't have 'the right gauges to be sharpened'...?

 

The main difference in the other screenshot is indeed mainly the amount of trees (pixels). So something IS working...

 

Hm, would be a shame if this all leads to nothing... but that's always a risk with tweaking... ^_^

 

 

See my previous edit Jeroen.

 

See this post which I was typing in the meantine LOL ^_^

[ad_verbum 0]

I've always been told that I should use CLAMP for FSX and not ALLOW. Why was that again?

 

There are two reasons why Clamp is used:

First - negative lod bias always works against anti-aliasing. It forces mipmapping algorithm using higher sized texture than would be normally used for such distance from camera. For example using negative bias value = -2 will force displaying texture level 3 at distance where normally would be used texture level 5. Texture level 1 is default size (for example 1024x1024) and texture level 5 is smaller size (in this case 64x64). With negative bias =-2 will be used texture level 3 (5-2=3) what makes impression you can see more details but makes also side effect - bigger shimmering.

 

Second - using negative lod bias raises CPU, GPU and memory subsystem workload, forcing higher resolution textures in place where previously were used smaller ones. See difference in size of used textures, 256x256 instead 64x64 - sixteen times bigger and it affects many textures (ground, buildings, trees and clouds).

 

Because I found out that using ALLOW and then a Lod bias of something like -2.000 actually SHARPENS everything in FSX a LOT...!

 

You may say it is more sharp, but it is also more aliased so shimmering may be really unpleasant. There is much better method to get view nicely sharpened - use post processing shader with Luma_Sharpen.

[Dirk98 354]

There is much better method to get view nicely sharpened - use post processing shader with Luma_Sharpen.

 

How?!

(or just a link, please) :smile:

 

 

 

Thanks,

Dirk.