What is it? What does it do/look like?

[Freke1]

I have no idea. Someone care to explain (with/without pictures) or with a link?

from games:
Bloom
HDR
Depth of Field
Anti-Alias
Motion blur
Post process effects

from the driver:
Gamma
Anisotropic filtering
Force mipmaps
Conformant texture clamp
Extension limit
Trilinear optimization
Anisotropic mip filter optimization
Anisotropic sample optimization
Gamma correct antialiasing
Transparency antialiasing
Negative LOD bias

there are probably more...

The only ones I know the effect of is Anti-Alias, Motion blur and Transparency antialiasing.

PS: I'm not keen on all the postprocess effects - the make the games look like a fairy tale.

[sharky]

i can try, but i am not shure about what i asay..

(by the way freke check this out: http://www.mtbs3d.com/phpBB/viewtopic.php?t=758)

from games:
Bloom ---- it is when ingame looking at a window or at a light you see the window "shine".. (see image)

HDR ----- High Dynamic range - much better light effect. (see image)

Depth of Field ---- the distance ingame youre watching at is focussed, the rest is blurred.. very cool effect. (see clip)

Anti-Alias --- something to eat i think

Motion blur ---- if you drive fast or move (depends on the game) the surroundings are blurred (see clips)

Post process effects ---- effects wich are applied to the output image, after it has been rendered. for example when you look at a granate. also motion blur, HDR, depth of field are postprocesing effects.



from the driver:

Gamma ---- the relationship between the brightness of a pixel and its numerical color value. (0-256 for every color)

Anisotropic filtering ---- if oyu look at the floor ingame, near you the quality is ok, but far away (how far depends on the game..
usually some meters) the floor looks washed. AF prevents this ugly effect.

Force mipmaps --- a sequence of textures which improve the way textures appear.

Conformant texture clamp -- this is difficult. i copy the reply from another forum. personally i dont understand it: The feature in question is the behavior of GL_CLAMP texture clamp mode, which by spec clamps the coordinate to 0.0 - 1.0 and with bilinear or other filtering modes takes the samples outside the texture from border color. NVidia hardware before Geforce 3 didn't support this, but behaved like wrap mode GL_CLAMP_TO_EDGE, which samples the texture edge pixels instead of border color. Many games that were coded on older NVidia cards assumed this wrong behavior (and displayed varying degrees of artifacts on Ati, Matrox etc. cards, like the infamous "cage" skybox in Tribes 2) so NVidia retained this buggy behavior as default and only recently added the option.

Extension limit --- dunno didnt find it even on google

Trilinear optimization --- the highest setting in "force mipmaps"

Anisotropic mip filter optimization --- from google: If your 'Texture Filtering - Quality' setting (see further below) is not set to High Quality, this option can be set to On or Off. If set to On, it uses a different texture filtering technique resulting in a slight drop in image quality in return for faster performance. If you want the highest quality graphics set this option to Off, otherwise set it On for best performance.

Anisotropic sample optimization ---- same as above

Gamma correct antialiasing ---- from google: This setting only works on 7800 series graphics cards or newer, and if set to On improves color quality and further improves the reduction in jaggedness for a slight peformance hit. I recommend it be enabled unless you want the absolute fastest performance. See Antialiasing Setting further below to see what Antialiasing does.

Transparency antialiasing ---- you know

Negative LOD bias --- LOD is the Level of Detail, and in some games you can alter the LOD Bias to sharpen details on screen

bloom:


HDR:


depth of field:
http://www.youtube.com/watch?v=84qSHb555xU

motion blur:
http://www.youtube.com/watch?v=9oiK7oPv8qY
http://www.youtube.com/watch?v=kq8EXQ7_n2A

anisotropic filtering:


negative LOD bias (lol.... )




hope it was helpfull and correct

bye

sharky

[Freke1]

Thx Sharky. Great info.
I've played a little AA - maybe I'll download it this weekend.

PS: don't eat Anti-Alias. Bloom taste much better...mmmh

[Jahun]

The ones on "the driver" are a bit technical.. so I'll skip those.. but the ones from the games: (every answer is: "afaik")

Bloom
Sort of a trick, to mimick the effect of very bright lights. If you look into a bright light, you will see a halo around it. I am not sure, but it can be due to the imperfections of your eye/lense that make the surrounding area light up too. Light gets slightly scattered away from their perfect path, and this slight amount gets noticable when the source is high. In games, the mimick it by taking the bright spots and blurring them stronly and pasting them back over the original image. So you get a halo. Thus also why it gives S-3D issues.. it is postprocessing. Nice touch though.

HDR
This is a cool, and sort of extremely obvious one, though you wouldn't think about it quickly. See it like this: black and white images for instance, go from 0 (black) to 255 (white) in color. The numbers can be anything really, you could remap them, and have 0 be black and 8924892374834 be white. You'd have soooo many graytones it'd be great! wewt!. So what is the catch... The problem is, you have white.. yay. but you have no super-white or mega-white even. That's what HDR fixes but it can't show it to you easily. HDR catches a great dynamic range of brightnesses, something your eye can do too, but a LCD or anything can't. The range of a LCD is quite limited, especially compared to our super eyes. So if I have a bright scene having a white sheet of paper and a sun, your eyes will see both as white/bright but the sun extremely brighter. Make a picture of both and you'll either end up with both being totally white, or the sun nicely yellow but then the paper would be completely dark. (depending on exposure times)

So if a game has HDR incorporated, it can't really show you the full dynamic range, the LCD just won't allow it too, but it can use it during the renders.

Perhaps I can explain it like this:
A scene has 3 balls, all of them are reflective but in rising order. One is only very slightly reflective, middle is quite reflective, and the last one is like chrome. (this works for diffusive light etc too) Anyway, the game lights this scene by a HDR map, just a images wrapped around the entire scene like a circular colored piece of paper. Now you'd look at the chrome one, and see the surroundings (the HDR map) strongly reflected, it is so bright, that most of it is perfectly white. The middle ball however only shows the sky as bright and white and since it is more dim, you can see details and colors in the rest, the least relective of the balls would show the sky as nice blue, and the buildings as dark/black.

I hope you get what I mean here..look at wiki for this balls example.

It allows for very realistic lighting by using image maps

edit: so the renderer allows for this higher range too, it is not just the images that have this range, the engine must understand it, and keep track of it.

http://en.wikipedia.org/wiki/Image:Hl2hdrcomparison.jpg

is a nice example. The water reflects the light at say 50% or so.. in the right example, without HDR this leads to a brightness of 50% of full white, is some grayish something. On the left, HDR is incorporated.. so the perhaps 3x normal white clouds, get 50% reflected, leading to 1.5x normal white and when rendered to screen, still lead to pure white.. get what I mean?



Depth of Field
Your eyes have a focussing distance, like any lense. Objects at that point are sharply projected on your retina.. others are not.. Games mimick this, by blurring objects (pixels really) that are not in the focus point (z depth).. further away from it, more strongly blurred.

Anti-Alias
Has to do with the digital nature of images.. the 3D scene the game is made of, is nice and fluent, but as soon as it is rendered to screen, the engine must take samples.. Think of a diagonal object... it will have steplike pixels at the edges, due to this sampling.. one pixel will be just "on" the obejct, another may not.. This leads to strong pixelation especially at borders of objects. (steplike lines) To fix this, the engine can render the same image a few times, in the mean time ever so slightly changing certain parameters to make the sampling vary a bit. These images are then blended on top of eachother and you get a better/smoothed out image. Ofcourse, rerendering entire images takes alot of time.. and fps drops. A trick to alleviate a bit of this is to only render those pixels that are close to a object border, since these are the tricky areas anyway.

Motion blur
The refresh of eyes are a bit slow.. so the thing you just saw is lagging and keeps on showing for a bit.. if things in your vision move extremely quickly, this gives a motion blur.

Games mimick this by blurring those moving pixels towards where they came from. Bit of a tricky algorithm really... quite a few pro renderers didn't have this correctly untill recently..

Takes the stuttering out of fast images, can be quite cool. See upcoming Crysis for a example of this (if somewhat too strong )

Post process effects
Anything you do to a rendered image after it is done. Sort of like quickly applying a photoshop macro on each frame before it is shown
Can be anything like glow/bloom, blurs, color filters etc..

I hope it made sense..
I write way too lengthy posts..

[sharky]

heh this was a good post.. just didnt understand one point... the HDR... from what i understand here unless you have a 50000000000$ graphic display this function is useles... right?

bye

sharky

[Jahun]

Sharky:

well, a HDR image can't be shown in its full range at the moment, and maybe never will I guess.. but who knows. It won't be easy watching though, like looking into a sun all the time

But you don't need a expensive display at all.. in fact, there is no such thing. The HDR already works nicely.

Check that HL2 image url I wrote, it shows the effect quite clearly. All there is too that image and HDR in that one, is that the reflection in the water stays pure white.. it is way more realistic. There may be subtler effects somewhere depending on how much they implemented, but I think it is mainly on reflective surfaces. Or transmissive like this one:

http://en.wikipedia.org/wiki/Image:Lostcoasttrnsmsn.jpg
In the dark inside of that church, relatively the light outside would be enormous.. just think of it in real life.. you standing in that dark church looking at a white piece of paper which looks perfeclty ok white to you, and all at once, someone opens a window... that will be alot brighter even and your eyes will adjust. This you can see in those games easily, move from a dark area into a bright one, or quickly look into the sun of HL2 and you see this adaptation.

Now check that image of the church, you just moved inside it, and the screen adapted to it's darkness and you can see everything inside.. outside must by now be in comparison extremely bright, since your pupils just went very wide to accomodate for the low ligth environment. Now see that window? It is say 50% transparant.. if you wouldn't have all this true HDR the outside light could not be brighter than 100%, so after 50% transmission, you'd end up with a dull grayish window. Which would not make sense at all, since you can imagine, the window should be very bright still, since the inside is relatively dark.

If you look straight into the window, the engine may adapt as your eyes would, and adapt to the brightness, and show you color and details again.

Get what I mean?

In a non-HDR scene, with nothing exceeding 100% brightness, you'd end up in a dull and dim world.. unless you make a zillion tricks and cheats etc.. with HDR it all works out from itself.

edit:
Combine a bloom like filter over a HDR image and it looks even cooler, then you add a glow to these very bright areas but not necisarily to all white areas, since some are more white than others..
heh.