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Running mltiple versions of UE4 has stopped working

Ive been building new versions of UE4 but keeping older versions for backup. I downloaded and built 4.1 and built a new project for terrain testing. I only have limited memory (4Gb) but at preview build levels would manage to build the lighting for the 4096x4096 map. I then built the updated 4.1.1 code and the editor couldn’t build the lighting any more even at preview level. I then rebuilt the code for the first official 4.1 build and tried to run the lighting again but get the same error log run out of memory and lightmass crashed (also the same for the older build i have 4.0.2). Now when the UE4 loader tool starts it says projects are not associated would i like to update. If i select yes the loader locks up, If i select no the loader locks up. Problems only started after building the 4.1.1 build, any idea’s? If there’s anything that really needs immediate TLC it’s swarm and lightmass, memory management is rubbish, 4GB main mem should be fine (works with every other high level renderer i use, but yet lightmass can’t even do simple scene’s without memory space issues). Please someone tell me a solution or Epic devs put some time into the efficiency of lighting builds.

Cheers KB

Memory is going to be a bigger issue in a game engine than it is in other renderers, it has to load a lot more data so it’s actually quite easy to run out of memory especially if you’re using terrain.
If you went to a new version and tried to go back to an old version I don’t think you can do that, if the files were used in the new version they may be modified in a way that won’t be able to go back.

Hey Viper, Cheers for the feedback. But Lightmass is as far as i understand just a photon mapping tool, has no higher workload then any other raytracer,photon mapper or path tracer (especially when your talking about just light builds). Lightmass is old news, There are better alternatives that are completely open source even for commercial use like Embree or Cycles that far better utilise memory (Even though Blender is one of the most inefficient memory tools ive ever come across, But Embree is very memory efficient).

It’s the weak point in the UE4 right now, Ive got an AMD HD 5850 card (naff) but in DX11 it runs just fine, Opengl is broken on the other hand but either shouldn’t effect what is basicly an offline renderer mode. Annoying to be able to run the engine just fine even on my old card but not be able to even build the lighting offline for the levels im creating (even though if i build those levels on a machine that can do it runs in real time just fine even on my system).

It’s a pipleine block right now (or better known by people in the studio as cock blocking). Had a chat with another dev earlier who told me he had simular problems and had to reinstall his windows platform to get back to ground zero, that’s in my case 12 hours of work with all the drives i have.

Lightmass isn’t the same as other renderers, you end up having to load a lot more into memory because it has to contain all of the content in the level including meshes, textures, and lightmaps. If you use terrain it can take a lot of memory to render if you also have lots of foliage. The number of lightmaps would be a big issue with terrain since it takes up such a large space.
After the lighting is built and you play the game, it only has to load the things that are visible, and it can take advantage of stuff like instancing and level of detail.

Lightmass doesn’t have to load anything into memory that any other renderer does, Full on path tracers and raytracers have to have all geometry and texture data in memory bud. It’s exactly the same as any other offline renderer (just not as evolved). It doesn’t need light maps as that’s exactly what lightmass is for, Building the light maps. In my example all i have is the terrain, Not a single other thing and it still can’t do it. Running the result of offline bakes is far harder then building the lighting data offline in the first place that can use the full power of C++ and all the intricacy’s of what right now CPU’s can do with raytracing/Pathtracing/Photonmapping that GPU’s can’t due to architectural weaknesses that GPU’s havnt got round yet. There’s no excuse why lightmass is so poor.

Edit: Even if we get given a command line lighting build tool that doesn’t need to load the editor to conserve memory, Tile based rendering, many ways to resolve the memory issue with lightmass. Right now on a small system it’s pretty much usless for even semi large scale scene’s. I don’t even care if it takes 12 hours to build the lighting, I just need the engine to be ABLE to build the lighting.

The larger the lightmap resolution, the more memory it requires, terrain usually has large amounts of lightmaps, if you don’t have enough memory you won’t be able to render. Simple as that. You can try reducing the lightmap resolution on your terrain until it renders, or make smaller terrain, or get more RAM. Those are your options.