A couple weeks ago we covered some very impressive screenshots of the recreation of Half-Life 2's City 17 by PolyCount forum user Logithx. Those were made in the Unreal Engine 3, but Logithx was determined to rework the scene in Unreal Engine 4.

Apparently, he already started, but that's not all. He posted a screenshot comparison showing the massive improvement in global illumination between the two versions of the engine. Here's what he had to say about the changes.

I don't think people will want to drop Lightmass anytime soon. The indirect lighting seems to have gotten a huge upgrade in Unreal 4. Working on environments that depend mostly on indirect lighting has become much more enjoyable rather than frustrating. I also feel much more in control, in Unreal 3 you always had to either massively boost the indirect lighting universally (which gave baking problems and looked ugly in many places) or use hundreds of dim 'fake lights' to give the illusion of indirect lighting.

Notice how the sunlight in Unreal 4 bounces correctly onto the train to the right, and even goes up to the ceiling to illuminate the panels and supporting structures.

You can see what he means by yourself in the screenshot below featuring the same Half-Life 2 scene in both the old and the new incarnations of the engine. If you're excited to see it applied to actual games, I am too.