Hdr

#1 HDRI (High Dynamic Range Image) is something that non-game related 3D artists have been using for quite some time now. A HDRI file is an image with 16-bits per channel (your normal JPEG or PNG is only 8 bits per channel) and this extra light information that is contained is sampled, campled and adjusted to give the exposure. The biggest benefit of it is that you can get accurate light representation at a particular point or camera position (usually sampled through an image of a mirror ball) and then force this light information to essentially cast light on everything around it (720 degrees). Essentially if you were to look at it in laymens terms, think of it as an ambient light that has emits photons 720 degrees from a point and each photon holds a different amount of light information that is picked up by the surface that it hits. It is one of the reasons why VFX in Film and TV looks very seamless now because the lighting that they use when they capture the actors on film is exactly replicated on the 3D props they build around them so it all feels natural.

IMHO HDRI itself is pretty cool though not a real must have in games. As cool as it may be, a game artist with half a brain and knowledge on lighting can use stock lights (such as you would find in the Lighting Pack) to create just as beautiful of an environment without the cost of performance or pre-loading calculations and honestly most people would never notice unless they knew exactly what to look for.

The reason why HDRI looks so awesome in Half Life 2: Lost Coast really comes down to two extras that they did but haven't mentioned as much. 1) More shaders to simulate things like specular bloom on surfaces (Specular Bloom can be best though of as a glow that light casts on a shiny/reflective surface when hitting it at a proper angle) and 2) Doing some light exposure sampling code that simulates the changes in your eye that you experiance when you go from a darker environment to a brighter environment.

Note: Item #2 is one of the new features that John Kabus is working on with the Lighting Pack and demoed at IGC. Very awesome work there John!

That's my 2 cents on the subject. Its cool but not a must have and certainly not worth the accolades that Valve is getting when you really understand what is going on.

Logan

#2 Except HDR dynamicly adjusts depending on where your looking, it is fairly easy to fake though. The problem with the HDR in far cry is that is simulates what a digital camera would see through a lense. The Human eye is far more advanced and compensates for a lot of things better. So it really isn't that realistic for a FPS.

It is a nice effect though, unfortunately all the best use of it has been in game that require pixel shader 3. Splinter Cell Chaos Theory, Far Cry etc. In FMC we faked HDR with clever use of multipass radial blur and 2X modulate blendmode on a per model basis using DX7. Worked pretty well so long as you watched your polycounts as getting anything near decent results required 2-3 passes to look good.

#3 Lens Flare isn't all that realistic either, yet people still code it in.

In some ways, simulating a camera is more 'realistic' to an untrained observer than simulating an eyeball. The camera matches up to what they're used to seeing on a CRT tube when they watch TV, so it's less jarring to see on a monitor.

#4 TSE supports SM3 HDR custom shaders. I don't know if anyone has actually written one yet but it would work. It's on my personal to do list.
This does not come with the EA. It's something you would have to add as a custom shader.

#5 Right, clarification of a few things:

1) Mittens has been working on a sm1.1 HDR implementation, and dont kid yourself if you think that HDR requires sm3.0 only
2) to be completely literal, no one's simulated HDR of the eye yet at all, we've just been simulating how a camera works. even HL2's version is how a camera would work with lighting. If you wanted eye-based HDR, you'd need a few things different:

A) THERE IS NO MAGICAL GLOWING SURFACES IN LIFE
ie, in HL2's HDR, you'll get surfaces that do an "overbright glow" to simulate the HDR effect. The problem is, this is how a camera reacts to high lighting. an eye reacts completely differently, in that it starts to bleed akin colors together. Your not going to have a concrete wall that looks like it's glowing, instead your going to get where colors that are close together washout and you lose lesser details.
The only instance of glowing ever perceived by your eye is either:
I) A direct light source, ie a lightbulb, or the sun
II) a surface that has ~100% specularity, and is capable of refelcting back the power of a direct light source. In no other instance does the eye perceive a bloom/glow effect

B) HL2's take on apature is light exposure. However, with an eye, it's more like color exposure.
As the eye takes in light, depending on the size of the pupil, you get an adjustment of how much light the eye takes in. however, instead of lighting control as HL2 implements it, it should more accurately be simulated in how wide of a color range the eye can perceive based on lighting. Being that all color we see is light based, as the eye adjusts it's apature, we either allow a greater range of colors to be viewed, or a lesser one. If the eye takes in too much color in at once, it'll shrink the pupil so that it can take in a more manageble sum of colors.

So is the current versions of HDR used accurate? Well, yes and no. Yes, it's accurate from a camera stand point, but it's pretty well completely the opposite if you're trying to simulate an eye.
So really it's all about which way you wanna go at. A camera/cinematic experience of lighting, or an eye based/more realistic viewpoint.

Ignoring all this, Hl2 did an awsome job on the camera based-HDR, and it looks nice. :)
FC's,however, makes my eyes bleed :p

Enough ranting from me, carry on :)

#6 Here is a screen from Nvidia's site. SM3.0 vs SM2.0 HDR..

#7 The Glow on the second shot is the worst shader effect I've seen. NOTHING I've seen in even PS 2.0 HDR looks that horrid! (I use ATI cards, though. Nvidia may be different).

Jeff is completely right, but I've seen lots of overbright glows in reality. Mostly its shallow water, prism glass or flat metals. You cabn't have True HDR on a monitor, it's like having True 3d on a monitor. It's only Pseudo 3d, its simulated to look 'True' using Vecotrs, the way HDR simulates it by glowing things to look cool.

#8 I think the point on the nvidia screen "get the power" thing promoting sm3.0. Is real time shaders in a game vs scene rendering.

#9 Corse you can have true HDR on a monitor! Its just gonna cost ya . . about 49,000$ to be exact!

http://www.bit-tech.net/hardware/2005/10/04/brightside_hdr_edr/1.html

#10 Good explanation L Foster. I wasn't so impressed myself; it did feel somewhat "uncoordinated" as a lighting mechanism, and I think that explains why perfectly. smoke and mirrors!

#11

Quote:
The reason why HDRI looks so awesome in Half Life 2: Lost Coast really comes down to two extras that they did but haven't mentioned as much. 1) More shaders to simulate things

Yea like the Sky glow shader in TSE EA

#12 Randy: That's just the Sky with a little bit of glow. It's not anything like HDR.

#13 I never said it was .. he was talking about HL2's use of shader "extras".

According to Timothy Aste it's volumetric light & glow shader (the one in my screen).

#14 You can get HDR up and running in TSE in a matter of minutes.. if you know what your doing.

#15 Yea there is a good post on it. But the code is not in a resource or TDN article yet. I just ordered a 6800 so I can do some sm 3.0 experiments. Hope to gather up what people have done and get a community resource on HDR for TSE EA owners. (Trying to pimp out TSE sorry... it's so sweet).

#16 For those people thinking about upgrading to a Shader 3.0 capable card right now, and cant afford a 7800, I would hihgly recommend a 6600GT. The Average performance isnt that far of a regular 6800, and they are pretty cheap.