PC Hardware & Games

Video: 5
Sound: 5
Gameplay: 2

Half-Life 2: Lost Coast is ostensibly a tech demo for high-dynamic range (HDR) lighting. While it is a fun quick play (maybe 20 minutes if you take your time), what it showcases is far more impressive and merits discussion.

What you've been missing

Video games, like pretty much all TV and movies, have a fixed gamma. So, if something on screen is sort of bright, in the next scene it will be sort of bright, as well. The brightness of everything, for the most part, is kept at a constant level. This is done on purpose-and when it isn't done, that too is done on purpose). This technology, however, does not mimic real life. Say you're leaving a movie theater. You're walking down that short, creepy hallway under the screen to go outside. It's dark, but you can make out the walls and the people around you well enough to figure out which way you're going. Suddenly, someone opens the door to the outside, and you're blind. Outside is too bright to see, and now inside is too dark. After a few seconds, your eyes adjust, and you can see clearly. This is one of the primary things HDR seeks to remedy. It acts like the slow moving iris in your eye, not the stationary one of a pre-lit movie or TV scene. (Yes, I know video cameras have auto irises, but stay with me-HDR is like that too). So, if you stare at the sun, other dimmer things will be harder to see. If you're inside looking out, everything will be too bright to see. In essence, what Valve is doing is adjusting the gamma, on the fly, depending on factors like where the player is, what environment is around him, where he's looking, and so on. It's truly incredible. It adds a level of realism that you might not have noticed was lacking. To add to that, there is a commentary mode where Gabe Newell himself and several members of the build team lead you through aspects of HDR lighting, level and character design, and more. This was very interesting. Below are a few screen shots to help demonstrate what HDR does, for those of you without Half-Life 2 (gasp) or without a video card that supports HDR.

The top picture is normal video-game lighting. Notice that you can still identify the detail on the edges of the metal in front of the sun. If you have set up your monitor well, you will also notice that you can see the detail on the inside of the support beams. With HDR turned on in the bottom image, you can see the sun is bloomed out slightly, obscuring the detail in the edges, and making the support beams (now backlit) only silhouettes.

Here on the lower image, you can see that the back of the big rock is too dark to see, where, in a normal video game, it would be just as illuminated as the rest of the scene.

The top picture is a church as viewed with "inside eyes." The bright sunlight streams through the window. The lower picture is the same scene as viewed with "outside eyes." Now the sunlight is more manageable, but the rest of the room is too dark to see. How cool is that?

Here is one of the commentary bubbles, describing the blooming effect of HDR lighting (on the right) compared to normal (left).

Lastly, when you play this free level, ask yourself, how did Geoff get here? (No cheat codes, thank you).