I´ve had a look at the Modular Building Asset on the Marketplace and the asset is good, no doubt about that. But I was wondering if it is a good idea to have so many individual pieces, since every bit gets a lightmap. I tried to bake the demo that comes with the asset and it took ages, actually I canceled the process in the end :-/ .
Wouldn´t it be better to have modular pieces in your 3D package and then construct larger modules based on the theses pieces? You would also have less lightmap-seams.
the answer is as always “depends”. as a general rule of thumb - stuff that will almost always be on screen in it’s entirety should be a single piece. but you have to be aware that if only a small corner is visible the entire thing will have to be rendered and culled. so it might be overkill to have an entire building be one piece but maybe having each facade be one piece or maybe only a story of a facade…
combining modular pieces earlier in the pipeline will obviously restrict you in terms of easily changing stuff later on though.
The main thing with Modular vs unique object is that pieces can be more easily culled. If your fighting performance or lightmap quality this would help greatly.
Using the building example, by having separate modular pieces these can be divided up into levels that can be streamed in and out or not even using the levels you can set a specified cull distance. The editor does a good job of helping with this as is, and by having multiple modular pieces vs a single unique model is much more efficient.
With regards to lightmaps you can get a better lightmap bake by using a smaller lightmap resolution since there is not as many UV shells to fit in the 0,1 space. If you have a large single object, you’ll be using a larger resolution lightmap to get decent shadow quality. Where you may see this as a plus for not having seams caused by indirect lighting in the bake you’re hurting more by having a larger lightmap resolution texture.
Using a 256 vs 1024 lightmap resolution is much more performant. Seams can be fought by adjusting the indirect shadow quality and smoothness settings in the World Settings. Using other meshes to mask these areas is also recommended.
You also mention that the light build is taking a while. Lightmass is a very intensive process and can use a lot of resources. Some things to consider (not all of these will apply depending on your system setup):
Use a Lightmass Importance Volume
Increase your RAM
Use Lower Lightmap Resolutions
Larger scenes, especially with a lot of lights and objects can take a while to build due to all the calculations that are needed.
Thanks a lot, Tim and divi for your answers and opinions. I absolutely understand the advantages of modular pieces and my idea was not to build a complete building in the 3D package, but just larger segments. For example a wall of the building which consists of modular windows, window-ledges, window shutters, etc.
I think you´re right, divi, and it just “depends” and I will try it out and do some testing. Working with UE4 is so much fun and I´m really looking forward to the next release .
Bye,Michael
and I will try it out and do some testing. Working with UE4 is so much fun and I´m really looking forward to the next release 
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