LOD Bias Adjustment - Found a way to change/adjust it (NVIDIA), setting not "broken"

S

Spinelli

Banned
So people have been saying that the whole LOD Bias adjustment thing in NVIDIA Inspector has been "broken" for some time now. Since I think previous to Driver Version 300. I tried it and couldn't get it working either. Today I decided to research it again and I found out that actually there are 2 ways to get it working

NOTE: It doesn't matter if "Texture Filtering - Driver Controlled LOD Bias" is set to "On" or "Off", and if "Texture Filtering - Negative LOD bias" is set to "Allow" or "Clamp". The adjustments will work regardless of what these are set to.

- Method 1:
All you do is set "Antialiasing - Transparency Supersampling" to "AA_MODE_REPLAY_MODE_ALL". THAT'S IT! Now you can adjust the LOD Bias (DX) to whatever you want, + values for blurrier, - values for sharper. It doesn't matter what other combinations of settings you use for AA Mode, AA settings, or any other settings, this seems to work regardless.

- Method 2:
Set "Antialiasing - Transparency Supersampling" to any of the Sparse Grid Supersampling settings.


The magical "Alt-M" in RFactor 2 may have negated the need for the good old LOD bias adjustment that was so popular back when it was always working (Just set to "Clamp" and then adjust the amount), but anyways it still works and is indeed not "broken". I'm sure many of you play other ISI based sims (Eg. RFactor 1, Game Stock Car, GT Legends) and possibly other games as well, that you used to adjust this setting for before we all thought it was "broken" so ya, it should still be useful for many :)

Thanks to http://forums.guru3d.com/showthread.php?t=376933 post #7 and post #12
 
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Does that allow you to clamp and adjust though? This is all new to me, but I thought the 'old way' was to clamp everything to zero and then adjust if needed. If what you're saying here only allows +/- adjustment without first clamping, you're still at the mercy of track makers because some textures may have zero while others have -3, so if you apply a +2 adjustment across the board you'll end up with some overly blurry textures. No? :)
 
Just made some tests. I can valid the first method. The second one killed my fps (126->86) and I didn't retrieve the image quality than with ALT+M

For this first method, the difficulty seems to found the good value. I tried several values without retrieving the exact effect of the ALT-M, and ALT-M applied on top of that should be a cumulative value as all goes really blurred (so don't do both, or just try for fun). Anyway, that seems possible, just need to test all possible value. My goal is to retrieve the exact same quality and fps impact than my current AA Level 4 + ALT-M. So the idea will be to ask to the dev which value the ALT-M induce.

Good find Spinelli, thanks! :)
 
YoLolo69 said:
So the idea will be to ask to the dev which value the ALT-M induce.
Click to expand...

Alt-M sets everything to zero bias. Spinelli's trick sounds like it could be used to then force everything to e.g. -0.5 or -1.0 via the driver, if so desired.
 
Yeah, sounds like you can use it as an adjustment on top of Alt-M (which acts as the old clamp, which doesn't work with newer cards).
 
Lazza said:
Does that allow you to clamp and adjust though? This is all new to me, but I thought the 'old way' was to clamp everything to zero and then adjust if needed. If what you're saying here only allows +/- adjustment without first clamping, you're still at the mercy of track makers because some textures may have zero while others have -3, so if you apply a +2 adjustment across the board you'll end up with some overly blurry textures. No? :)
Click to expand...
No idea, I don't really even know what "Clamp" even means. I thought "Clamp" just meant that it's now user adjustable (from -3 to +3) rather than just stuck at default. Also, I thought default was 0.0? I tried manually setting it to 0.0 and it seems to look the same as when I disable the user adjustable lod bias setting.

Yes you're right about the blur though, it get's horribly blury after a certain point, I thought that was normal when setting the lod bias too high. So you're saying that when "Clamp" used to work that you could set a real high lod bias and things still wouldn't get blurry?


YoLolo69 said:
Just made some tests. I can valid the first method. The second one killed my fps (126->86) and I didn't retrieve the image quality than with ALT+M
Click to expand...
It hurt your fps because you set it to either 2x, 4x or 8x sparse grid supersampling, which is a very intensive form of supersampling. I don't think method 1 will affect your framerate though as that mode seems to not do anything in terms of antialiasing while "unlocking" the LOD bias user adjustment.
 
Can you guys explain what the difference between a manually configurable LOD bias with, and without a working "Clamp" setting is? As long as you can adjust the LOD bias then what does the "Clamp" setting allow on top of that?
 
I think Clamp set everything to 0. So same thing alt-M does now.

Some time ago when lower levels of AF were used, things got blurry in the distance but white lines and fences were probably most noticeable. Negative bias was set on those textures to compensate, maybe up to -3 or even higher (lower). Some other textures started to look pretty ugly with this setting, and were set to 0 or -1 instead.

So by only doing an across-the-board adjustment of +3 (for example), you'd end up with white lines on 0 and some other textures on +3: very blurry. With 16xAF the white lines look pretty good on 0, while grass or whatever would now be on +3 and will just be a blurred mess.

So the idea, I believe, was to clamp everything to 0, then maybe go -0.5 or -1 just to sharpen everything up a little.

If you can use Alt-M to set to 0, then your OP settings to adjust from there, it would achieve the same thing.
 
Clamp prevents anything below zero without changing anything above zero.

Sent from my GT-I9300 using Tapatalk
 
Very interesting find Spinelli!

Clamp sadly doesn't work, like you said, tested it myself and there were no differences whatsoever. Adjusting the LOD Bias without using Alt+M isn't a good solution though, because it simply adds or subtracts from the individual Bias each material has as default. For example, using +1.0 will blur the asphalt texture even up close, making it a total mess, while the white lines next to the track are almost not affected at all (see the shots with the +1.0 setting, the lines are still heavily aliased). Alt+M (setting EVERYTHING to 0.0 first) plus a little negative value afterwards can get decent results though.

Here are some comparison shots. First shot shows a fence nearby while the second one shows the white track marking lines pretty well.


Shot 1:

rF2's default LODs:


LOD Bias +1.0:


LOD Bias -1.0:


Alt+M:


Alt+M -0.5:





Shot 2:

rF2's default LODs:


LOD Bias +1.0:


LOD Bias -1.0:


Alt+M:


Alt+M -0.5:




So Alt+M is still needed to get the best visual quality. Without it, the white lines will still be heavily aliased while the rest is already super blurry using positive adjustments, that's because the track creators used super sharp negative values for the white lines and normal values for the track surface for example, sadly.

But very interesting find nonetheless, Kudos for that Spinelli. Now I wonder if a certain combination will make it possible to re-enable the Clamp setting... That would be awesome (and we wouldn't need to use Alt+M anymore).
This would be very welcome to restore rFactor 1's former image quality on older GPUs because we don't have an Alt+M override there. The Clamp setting is something like the holy grail to restore rF1's image quality (and would eliminate the need for Alt+M in rF2 as well).
 
Robert, in the endless playing with these settings over the years, some combinations of settings produce strange graphical artifacts (usually large flat circles) coming from the exhaust of some of the cars. Cars with side exhaust might have two, one from each side, or the open wheelers tend to just have one big circle at the rear. Have you experienced this effect? Do you know which particular setting causes it?
 
I've seen it once, yes, at the back of the FISI 2012 I think when I was running the 32xS mode. What's causing them: I don't know. All I know is that it resembles the positions of the backfire and heat haze effects.

I believe you refer to an issue which looks similar to this, right (see those 2 shapes beside the Arthur Merlin?)?
 
1. If "alt-m" is the same as "Clamp", then wouldn't "alt-m" + LOD Bias adjustment be the ultimate setting just like "Clamp" + LOD Bias adjustment used to be?

2. If the problem with a non-clamped LOD Bias adjustment is that it sets the values across the board, then how to we set different individual values rather than the same value across the board?
 
+1
Can't see any difference in the image quality as well. Question I have is whether it is a minor difference which you only recognize when doing screenshot ( would be a no brainer to me) or can the difference be recognized when driving?!


Sent with Tapatalk
 
Spinelli said:
1. If "alt-m" is the same as "Clamp", then wouldn't "alt-m" + LOD Bias adjustment be the ultimate setting just like "Clamp" + LOD Bias adjustment used to be?
Click to expand...

I think so, yeah. I feel like we're going around in circles here.

2. If the problem with a non-clamped LOD Bias adjustment is that it sets the values across the board, then how to we set different individual values rather than the same value across the board?
Click to expand...

I don't think you can. Each material can have its own bias, so without some way to change the materials you're stuck with what they are except for disabling the negatives (that's what alt-M does, right? I keep saying 'set to 0', and suggested clamp might also have 'set to 0', but I think both actually set all negatives to 0 while leaving positive values) and then making a minor adjustment if required.

Basically if you want to go and edit all the GMTs and repackage the track, you can set them to what you want, but then if you're going to do THAT you can just set them all to 'good' values and not need alt-M at all :)
 
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