I was curious…is there any way as of now to achieve directional lightmaps in Unreal?
I remember that in Unreal 3, before Epic implemented Lightmass…it was using BEAST and that had directional Lightmap support. Its actually one of the main Reasons the first Mirrors Edge looked so good. I would argue that this feature elevates the look of all normal mapped surfaces in indirect lighting by a mile and also opens up for some other fancy tech:
Indirect specular from lightmaps
In theory, this is a more approximated version of spherical gaussian lightmaps used in The Order: 1886. Since you store directionality in the lightmap, you can reconstruct the direction of the strongest light and basically add indirect specular from that.
This makes ALL rough surfaces look absolutely amazing without the need to add reflection Volumes! This is especially nice for geometry thats not perfect squares or geometry where box reflections would still bleed onto other surfaces all the time. Of course they cant provide reflections alone, but the feature adds a tremendous amount of realism and believability to rougher materials. If you have directional lightmaps, implementing this indirect specular is just a small step up.
All Naughty Dog games are using this tech now too and I believe it makes such a big difference. Also, getting capsule shadows also uses data like that but from probes instead…so “kinda” similar
Here is an example of a directional lightmap. You can clearly see how in the top left corner, the normal map details are getting green bounce light from the left and red bounce light from the right.
In the implementation we have right now, it just mixes the colors and becomes a total mess and does not at all care about the normalmap
After jumping in the editor in a baked scene and realizing UE does not have this even though even Unity does made me kinda mad. It’s been how many years of knowing how much this improves the realism in scenes? People were doing this back circa 2015 in engines. Specular occlusion is IMHO one of the most important things for image impact on the player, lightmap specular adds it to the static scene and adds specular NDF lobes for high roughness materials!
Example so people can immediately see the difference
And please don’t answer “use realtime gi” that is an insane answer when there’s so many genres of games that need high framerates.
I just don’t understand why UE wouldn’t have this when UE has so many other things that are incredible and useful like indirect light capsule shadows, distance field based indirect soft shadows, the incredibly fast GPU lightmass baker etc
A lot could be done to improve lightmapping in Unreal but the reality is that Unreal is built first and foremost to make Epic’s internal projects, and unfortunately right now that primarily means Fortnite. If Fortnite doesn’t need it, then it won’t be a priority, and Fortnite does not use baked lighting.
Paragon did, but Paragon is no more and Lightmapping in Unreal basically died with it. CPU lightmass works, but it is in maintenance mode, it doesn’t get any improvements itself. GPU lightmass appears to be basically abandoned, Epic says otherwise, but I have been testing it since it was added to the engine in UE4 many years ago and it is still not in a reliably usable state. Currently, ISM/HISMs won’t build correctly with GPU Lightmass if there is a stationary light in the scene (a bug which was present in 5.4 and remains unfixed in 5.5).
It’s sad that this is the state we’ve arrived at, but it’s not hard to see why. The running theme of Unreal 5 has been to support larger and larger worlds of higher complexity, and lightmaps don’t fit into that mold well.
I really wish there was a way to publicly vote for features and improvements that studios care about. Right now with these forums it feels like a lot of higher level important discourse gets buried in lower level beginner questions and posts , so much so that epic games end up not passing our needs to internal teams.
If we had that they would see how many developers are asking for better lightmaps, for blending between bakes for times of day etc. The thing with these additions is that they are not that hard to implement, lightmap specular just needs some code in the .usf files probably, blending between bakes is just making sure you have both loaded in memory and sampling both in the shaders, I’m sure their engineers could do this quickly, heck I might give it a try myself.
That makes it doubly frustrating.
But hey maybe that’s the intention, “just do it yourself if you want it for your game, we’ll be here making features that are always future looking and more for cinema than games.”
