Planning geometry layout and lightmap resolutions

Hello everyone! How are you doing?

Me and my partner have been working on a demo scene for Arch Viz, and now we need to polish some aspects of it. For this topic, I’ll ignore lighting, as there’s much information available and I’m not done reading it, but other things are seldom discussed. My knowledge is somehow limited and I’d like to improve with your feedback.

After some trial and error, I decided to model each individual room as a static mesh, but I was having light bleeding and added a static mesh “cover” to the outside, back then I didn’t test double sided geometry, but I’m still unsure if the material needs to have this option as well (I had to use it in the curtains for example). Is this “cover” unnecessary?


Then I though a 1024 lightmap would be enough for each room, and I’m satisfied with the results, but I’m having trouble with smaller objects. I’ve been doing my lightmaps in Blender (pseudo-automatic, manual adjustments, snap to pixel grid), and I’ve read that 4.11 is doing a much better job generating lightmaps, would you recommend using generated LMs all the way?


These plugs are the only thing here I didn’t model myself, 3000 tris! How do you approach this issue with small and sometimes complex objects? I’m using the default resolution of 64, would you increase it for the final quality?

How do you manage the LM generation and resolution to achieve consistent results in different scale objects, no leaks, etc.?

Another thing for curiosity, I don’t know enough to understand the nature of the following issues:

Is there anything I could do to fix this? Or do we have to live with it?

I hope you can help me understand this process a bit better, my workflow might be flawed and I don’t even know it, this is how I do it, I’d like to know how you do it. Let me know if you want me to provide more information.

Best regards!

  • John

Interesting post. I was just wondering the same thing. I’ve been adjusting my Lightmap res to keep everything “green” according to the lightmap res view un UE, but then my shadows lose quality… I guess it’s a balancing act.

From what I know, hi-poly models designed for 3Ds max are generally over-designed for UE and should be scaled back as much as possible if you’re looking at real-time rendering without losing detail as to not affect performance when you’re walking around in real-time.
You should try to do your own LMapping in whatever modelling program you use. This allows for better control should something need to be adjusted.

I’ve started to use decals for plugs or light switches. High res image decals!

@dylan86.exe Is it really optimal to have everything “green”? In the documentation it says red is “Max or greater than ideal texel density”]( I guess I’d have to use a resolution much lower than 64, but then again… I could never have such a high poly model for this. I’ll use my own low poly plugs and try to achieve green.

@heartlessphil This is actually very very interesting, but can you get the 3D feel? Do you need to have more than a simple material setup with normal map or is it enough?

Thanks for the input, but what if you’re crazy about close ups? Hi poly mesh + big resolution LM? Is this the “only” option?

I’ve also tried setting these objects as “movable”, but they don’t blend perfectly in the scene as a whole.

I’m not sure. Maybe someone else can step in and offer you an answer s to what it means exactly. I do know it’s best to have everything the same colour though. So if everything is Yellow and there’s one red part, make the red part yellow by lowering the LM. I’ve found as long as everything is the same colour, the lighting looks a lot better.

I’ve baked some similar power outlet before, don’t recall what lightmap res I used and I just unwrapped it with steamroller. It looked perfectly fine once baked but you’ll need the highest possible quality lightmass settings.

Decals materials are simple or complex, as you wish, but with 100% static lighting they need to be emissive to appear visible. So, to make em decent, you have to tune the emissive value carefully. You can even do POM materials that look very good. At this point not sure if it’s not just easier to make a 3d model of the power plug tho!

Maybe bake the hi-poly to a low-poly mesh with a normal map? like game assets are made.

The glass problem is due to the refraction ‘‘fresnel’’ value… personally I remove it completely for flat glass surfaces.

Just a little update, I re-imported the plug models and this time I generated the lightmaps in the engine, and I must say, the results were pretty perfect, default resolution at 64, only with some minor issues, barely visible. Yet, the lightmap density appears red, makes me wonder.

Of course, the best solution would probably be the hi-poly->low-poly bake.

@heartlessphil Thanks for the tip on the glass, I’m going to check that now.

Yeah I have found that if your uv map is good the lightmaps generated by UE4 aren’t too bad in most cases.

I haven’t tried the auto-generated lightmaps since 4.5! Might revisit the option eventually. But steamroller for 3ds max is so fast and efficient, it does the job pretty well too!