Antialiasing question

Jorgen

I'm curious as to what is causing the behaviour in the following screenshot:

aliasing.png


As you can see, AA is working fine on the car and everything else except the road textures. The AA settings I used in the shot was 8x and 4x multisampling on transparency. I have tried with "Negative LOD bias" set to both Allow and Clamp without any difference. Why isn't the asphalt textures processed by the AA?

I have tried using AA forced by the drivers as well as set in rfconfig, no difference, and I have also tried to use a texture without mipmaps, no difference, except a more blurry result.

Does anyone know if something can be done to fix it?
 
This is something that has been happening for ages with nVidia cards: the solution should be to se Negative Lod Bias to Clamp, then turn anisotropic filter to 8x or 16x and turn AA on, but this obviously costs a lot of performances with modern games (and the problem often is still there).
I don't know if this depends on how the texture/track has been realized, but I've always known it was a nVidia problem. What graphic card do you have? Probably this has been fixed on more recent models.
 
Exactly, that is related to texture filtering and mip map quality. With nVidia, you have ugly, blurry mip maps or ultra crispy with Anizo, but with visible sort of aliasing.
Ati somehow managed to get that right and you have sharp textures with Anizo without that kind of aliasing.
 
It might actually be a new driver issue, I'm on a GTX 460 with fairly new drivers. Not the very latest though, because they are worse when it comes to the corrupt graphics issue my other thread in here is referring to. I have tried "Clamp" without success, and 16xAF gave crisper textures but still the same aliasing troubles.

The material definition looks like this:

aa-material.png


The texture itself is a DDS/DXT1 with 11 mipmap images that look sharp if I open the file together with its mipmaps.
 
Yeah LesiU, you're right, it's when the mipmaps kick in that the AA stops working properly. (or so it seems anyway)
 
LesiU said:
With nVidia, you have ugly, blurry mip maps or ultra crispy with Anizo, but with visible sort of aliasing
Click to expand...

Well, in general you should have good quality with nVidia too by setting LOD Bias on Clamp (which makes the lines blurred) and anisotropic on (which will increase detail of far objects depending on how high you set it). This is not always enough: I'll try to take some screens too to show what I mean, even if I think you already understood it.
 
Should I really write all settings in my post just to show you, that I clamped negative LOD too? :) Pick that + Anizo x8, do screenshot and then switch to Ati... the difference is very noticable. I've hever got as good quality on nVidia, like I always had with Ati. That was with everything I went through, from 6800GT up to GTX460.
 
No matter how I configure things, the aliasing refuses to go away. I'm starting to wonder if this is another driver bug. (I have the 266.35 beta drivers installed at the moment) There have been plenty of AA issues with the 260.xx drivers so I guess it's possible that many of them haven't been fixed yet.
 
I have an nvidia card and I get this, infact this thread is great, now I understand why I get this so much. I overcome it by running antialias transparency with supersampling but unless you got a fast rig it will be a massive hit in fps. almost a 50% drop.

miannvidia.jpg


 
That's something different... ;-)
You are talking about aliasing on transparent objects (or with such attribute, like bitmap fence in this example). The thread is about having a sort of aliasing because of issues with texture filtering (lower quality mip maping... I don't know what's the reason).
 
LesiU said:
That's something different... ;-)
You are talking about aliasing on transparent objects (or with such attribute, like bitmap fence in this example). The thread is about having a sort of aliasing because of issues with texture filtering (lower quality mip maping... I don't know what's the reason).
Click to expand...

Ok, sorry about that, I will leave you to it. :)


Or,,


you could try what I suggested ;)
 
Remember that FSAA does not affect textures!
You are still refer to AA in relation to aliasing on textures which is incorrect approach.

What about setting bias to higher values? ie -1.5? It should make the result more blured and also make it lower quality.
 
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Negative LOD bias = Clamp has no effect at all for me. Is it possible to define the distances when the game switches between the different mipmaps? Or is that sort of implicitly done through the bias defined in the material?

After looking in the Photoshop DDS plugin config, there seems to be lots of mipmap creation options. Are there any "best practice" settings for those?
 
I have played around with some player file options I hadn't seen before:

MIP Mapping="1"
Mipmap LOD Speed="100.00000" // Speed (MPH) at which maximum mipmap bias is used
Mipmap LOD Bias="0.00000"

Sadly, none of them helped at all. Setting MIP Mapping to 0 resulted in a horrible flashing everywhere, and the other two options had no effect whatsoever.

I'll make an attempt to patch the GMT objects and reduce the bias on the material to see if things can improve.
 
Well, it got a bit better by setting the bias to -1: (was -4 originally)

aliasing-2.png


16xAF and filtering set to "High quality" in the nVidia control panel.
 
LesiU said:
Pick that + Anizo x8, do screenshot and then switch to Ati... the difference is very noticable.
Click to expand...

I know, I know: probably I haven't been clear enough, but what I previously wrote is how things SHOULD work, while in reality the result is not what you woud expect. :D
 
Yes, reality says - on nVidia it won't work like would like to and that's sad, because for unknown reason they just don't correct that :(


Jorgen, nice finding!

I know that such things are beeing done when there are low quality textures and someone wants to "sharpen" them (by altering LOD bias). But I have no idea why someone did that for this track, with such nice hi-res textures :confused:
 
I said to test greater value ;)

Lower numbers forces engine to use higher quality LOD for longer distance applying aniso filter over it. Unfortunately it does't work well on nV as said.
For example -4 is better for Ati because aniso filtering is better and overall effect is better when using higher quality lod.
On nV cards you have to make use of lower LODs earlier. -1 bias does the job.
 
Jorgen said:
Well, it got a bit better by setting the bias to -1: (was -4 originally)

16xAF and filtering set to "High quality" in the nVidia control panel.
Click to expand...

Hi Jorgen
hello where I have the same problem as you. can be more specific where this value change? on file .PLR line? Mipmap LOD Bias="0.00000"

thanks

.
 
I actually ended up patching the GMT files in the track. Normally you should be able to make an adjustment in the nVidia Control Panel though. Just right-click on your desktop and it should be in the context menu that pops up. Navigate to "Manage 3D settings" and set the property called "Texture Filtering - Negative LOD Bias" to the value "Clamp". That should normally do the trick, but for some reason that didn't work for me. I suspect it's something in the latest drivers that doesn't quite work as it did in older versions.

Hope this helps.
 
@Jorgen No, I use 195 drivers with GTX260 and the Clamp thingy doesn't seem to change anything either. More so when I use advanced 3D setup I seem to loose all filtering altogether. The best looking driver setting is 'use my preference emphasizing: quality'. Then most textures look good but some, but those lines often don't.
 
Yeah, Clamp seems to be completely broken, at least with rFactor. Or perhaps something else in the settings takes it out of the equation, so to speak?
 
A friend of mine says you need to set rF AA to x3 then it works best for unknown reason. Didn't work for me, but you can try.
 
You mean, "Level 3", in rFConfig? That is a big difference, because all that "Levels" of AA in rFConfig is just a mirror of what true settings you have in the drivers. That means, if you have 6 AA options in the drivers, then you will have 6 levels of AA settings in rFConfig (for nVidia, Level 3 = x8, Level 5 = x16, both are "pure" MultiSample modes, not Quincunx).

As for clamping option... that's strange, because not that long ago, about 2 months back, when I had GTX295 and GTX 460 for testing, I had no problems and the drivers were 260.63 (win 7 x64).
 
I got my GTX295 back and I must say, that picture quality on that card, compared to Ati, doesn't look that bad like I remembered it... actually, it looks very good, considered on what settings that has been achieved.
On both cards, rF was set to full/max details with Anizox16 and high quality texture settings in drivers.

1. Ati HD5750
a) AAx8 (box) Multi-Sample:

http://img17.imageshack.us/img17/6899/grab004d.jpg

b) AAx8 Super-Sample:

http://img593.imageshack.us/img593/1356/grab003t.jpg



2. GTX295, AAx16, with negative LOD clamped in drivers (260.63):

http://img341.imageshack.us/img341/5226/grab008q.jpg


Notice picture quality on red/white curbs on the left and on short straight before last chicane.


Of course GTX295 is much more powerful card, but on all newer nVidia cards AAx16 (Level 5 in rFConfig) does not provide that much fps drop.
With Ati, max what you can get is AAx8 with multi-sampling and that won't provide that much fps drop. Now, switch to Super-sampling, and your fps will drop A LOT. My friend did more tests on his 6950 and he told me, that the best results can be achieved with AAx4 with Super-Sampling.
 
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